Open Collections

UBC Theses and Dissertations

UBC Theses Logo

UBC Theses and Dissertations

Sulphate and bisulphite pulp yields within wood growth zones of Picea mariana (Mill.) B.S.P. and Pseudotsuga… Chiu, Shui-Tung 1968

Your browser doesn't seem to have a PDF viewer, please download the PDF to view this item.

Item Metadata

Download

Media
831-UBC_1968_A6 C45.pdf [ 5.57MB ]
Metadata
JSON: 831-1.0104182.json
JSON-LD: 831-1.0104182-ld.json
RDF/XML (Pretty): 831-1.0104182-rdf.xml
RDF/JSON: 831-1.0104182-rdf.json
Turtle: 831-1.0104182-turtle.txt
N-Triples: 831-1.0104182-rdf-ntriples.txt
Original Record: 831-1.0104182-source.json
Full Text
831-1.0104182-fulltext.txt
Citation
831-1.0104182.ris

Full Text

SULPHATE AND BISULPHITE PULP YIELDS WITHIN WOOD GROWTH ZONES OF Picea mariana (Mill.) B.S.P. AND Pseudotsuga menziesii (Mirb.) Franco. by SHUI-TUNG CHIU B Sc. Chung-hsing University, Taiwan, 1962. A THESIS SUBMITTED IN PARTIAL FULFILMENT OF . THE REQUIREMENTS FOR THE DEGREE OF MASTER OF FORESTRY in the Department of Forestry We accept tbis thesis as conforming to the required standard. THE UNIVERSITY OF BRITISH COLUMBIA JUNE, 1968. In p r e s e n t i n g t h i s t h e s i s i n p a r t i a l f u l f i l m e n t o f the r e q u i r e m e n t s f o r an advanced degree a t the U n i v e r s i t y o f B r i t i s h Columbia, I agree t h a t the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e and Study. I f u r t h e r agree t h a t p e r m i s s i o n f o r e x t e n s i v e c o p y i n g of t h i s t h e s i s f o r s c h o l a r l y p u rposes may be g r a n t e d by the Head o f my Department or by h.ils r e p r e s e n t a t i v e s . I t i s u n d e r s t o o d t h a t c o p y i n g or p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l not be a l l o w e d w i t h o u t my w r i t t e n p e r m i s s i o n . Department o f f- Or-gS fr-\/  The U n i v e r s i t y o f B r i t i s h Columbia Vancouver 8, Canada Date Au-^^t S~, /f&L? ABSTRACT Quantitative methods for sulphate and Na-base bisulphite micro-pulping and micro-analytical procedures were developed. Raw pulp and pulp carbohydrate yields were correlated with relative position within growth increments of black spruce and Douglas f i r . Profiles varied at different pulp yield levels and with pulping process. No profiles were simply correlated with wood micro-specific gravities. Maximum raw pulp and pulp carbohydrate yields within growth increments shifted from earlywood to latewood as yield changed from high(80 ^ 57.) to low(45 - 57=,) levels.' Delignification rate differed within increments for both pulping processes. In the in i t ia l sulphate and Na-base bisulphite cooking stage, latewood lignin seemed to be more easily removed than that from earlywood. At high yield levels (80 * 57<>) , the pulp residual lignin contents based on oven-dry pulp followed similar patterns in that maxima were found in early-wood, abruptly decreasing in the transition zone then slightly increasing in the latewood portion. At low yield levels (45 57.) , the residual lignin patterns varied slightly, or remained constant throughout the whole increment. Raw pulp yields, residual lignin contents and pulp carbohydrate yields (based on extractive-free water-free wood) were not significantly different for combined data of heartwood and sapwood, the two woods and two pulping processes, except for Na-base bisulphite pulp carbohydrate yields which showed significantly higher values for sapwood. Sulphate raw pulp yields and residual lignin contents obtained by combining data from a l l cooking levels and wood zones were not sig-nificantly different between the two species examined, except for Douglas f ir carbohydrate yield which was significantly higher than that of black spruce. For Na-base bisulphite pulping, Douglas f ir raw pulp yields and pulp carbohydrate yields were highly significantly greater than those from black spruce, whereas pulp residual lignin was not significantly different. - I l l -TABLE OF CONTENTS TITLE PAGE . . . . '. ABSTRACT . . . . . ; i TABLE OF CONTENTS i i i TABLES AND FIGURES vi ACKNOWLEDGMENTS x INTRODUCTION 1 REVIEW OF LITERATURE 3 A. Variation of Chemical Pulp Yields Among Coniferous Woods 3 B. Chemical Pulp Yield Differences Between Coniferous Wood Zones 4 C. Coniferous Earlywood-Latewood Chemical Pulp Yields 5 MATERIALS AND METHODS 8 A. Wood Sample Preparation 8 B. Latewood Percentage Determinations . 9 C. Wood Micro-specific Gravity and Micro-lignin Determinations . 9 1. Wood micro-specific gravity methods 9 2. Wood micro-lignin methods 9 D. Determining Micro-pulp Yields 10 1. Micro-pulping procedures 10 a. Wood sample preparation and pulping 10 b. Pulp yields, residual lignin and pulp carbohydrate yields 12 - iv -2. . Development of procedures 13 a. Micro-pulp yield 13 (1) . Effect of wood section thickness on pulp yield 13 (2) . Effect of screen mesh size on pulp yield . . . 14 (3) . Effect of sample position on screen 14 (4) . Determination of replication number 15 b. Residual micro-lignin 16 (1) . Sample weight 18 (2) . Digestion time and pulp solubility 19 (3) . Elapsed time and relative lignin content . . . 19 RESULTS 21 A. Intra-incremental Micro-specific Gravities And Wood Micro-lignins 21 B. Raw pulp yields 22 1. Within growth increments 22 a. Raw pulp yields . 22 b. Residual lignin contents 25 c. Pulp carbohydrate yields 27 2. Between wood zones 27 3. Between species 31 DISCUSSION 35 A. Variation Within Growth Increments 35 1. Morphology and pulp yields 35 2. Delignification and residual lignin contents . . . . 38 - V -3. Effect of carbohydrate degradation on pulp yields 40 4. Process and raw pulp yield profiles within increments at various yield levels 45 B. Variation Between Wood Zones 47 C. Variation Between Species 49 CONCLUSIONS 51 REFERENCES 53 - vi -TABLES AND FIGURES Table 1. . Coniferous earlywood (E) and latewood (L) chemical compositions from the literature based on oven-dry wood 64 Table 2. Coniferous earlywood (E)-latewood (L) raw pulp yields and residual lignins at various cooking times (T) from the literature and summary of present experimental values based on extractive-free water-free wood 65 Table 3. Description of stems and growth increments used in micro-pulping studies 66 Table 4. Absorptivity of lignins from woods and pulps of black spruce and Douglas fir 67 Table 5. Species, growth increment numbers, moisture content of wood sections and times at maximum temperature for sulphate and Na-base bisulphite cooks 68 Table 6. Sulphate and Na-base bisulphite cooking variables . . . 69 Table 7. Analysis of variance on the effect of various thicknesses of black spruce and Douglas f ir wood sections on sulphate and Na-base bisulphite pulp yields 70 Table 8. Analysis of variance on the effect of screen mesh size on black spruce sulphate cooking 70 Table 9. Analysis of variance on effect of between screen positions on pulp yields 71 Table 10. Analysis of variance on the effect of within screen position on black spruce and Douglas f ir sulphate and Na-base bisulphite pulp yields 72 v i i -Table 11. Calculation of replication number from three positions within growth increment for two species and two pulping process 73 Table 12. Effect of elapsed time on residual lignin determinations for Douglas f ir sulphate pulp and black spruce Na-base bisulphite pulp 74 Table 13. Distribution of wood lignin within increments of black spruce and Douglas f ir based on extractive-free water-free weight 75 Table 14. Distribution of wood specific gravity within increments of black spruce and Douglas f ir based on extractive-free oven-dry weight 76 Table 15. Sulphate raw pulp, residual lignin and carbohydrate yields within Increment No.31 (heartwood) of black spruce at three cooking times 77 Table 16. Sulphate raw pulp, residual lignin and carbohydrate yields within Increment No.47 (sapwood) of black spruce at one cooking time 78 Table 17. Sulphate raw pulp, residual lignin and carbohydrate yields within Increment No.30 (heartwood) of Douglas f ir at three cooking times 79 Table 18. Sulphate raw pulp, residual lignin and carbohydrate yields within Increment No.57 (sapwood) of Douglas f ir at one cooking time 80 Table 19. Na-base bisulphite raw pulp, residual lignin and carbohydrate yields within Increment No.31(heartwood) of black spruce at three cooking times 81 - VI11. -Table 20. Na-base bisulphite raw pulp, residual lignin and carbohydrate yields within Increment No.47 (sapwood) of black spruce at one cooking time 82 Table 21. Na-base bisulphite raw pulp, residual lignin and carbohydrate yields within Increment No.30 (heartwood) of Douglas f ir at three cooking times 83 Table 22. Na-base bisulphite pulp, residual lignin and carbohydrate yields within Increment No.57 (sapwood) of Douglas f ir at one cooking time 84 Table 23. Regressions of micro-specific gravity on position within growth increments 85 Table 24. Regressions of wood lignin on position within growth increments 86 Table 25. Regressions of sulphate pulp yield on position within growth increments 87 Table 26. Regressions of Na-base bisulphite pulp yield on position within growth increments 88 Table 27. Regressions of sulphate pulp carbohydrate yields on position within growth increments 89 Table 28. Regressions of Na-base bisulphite pulp carbohydrate yields on position within growth increments examined 90 Table 29. Analysis of variance on species, wood zone and species-wood zone interactions for raw pulp, residual lignin and carbohydrate yields in sulphate pulping (12 min max) 91 - ix -Table 30. Analysis of variance on species, wood zone and species-wood zone interactions for raw pulp, residual lignin and carbohydrate yields in Na-base bisulphite pulping (240 min max) 93 Table 31. Analysis of variance on species, growth zone and species-growth zone interactions for raw pulp, residual lignin and carbohydrate yields in sulphate pulping by combining cooking times and wood zones 95 Table 32. Analysis of variance on species, growth zone and species-growth zone interactions for raw pulp, residual lignin and carbohydrate yields in Na-base bisulphite pulping by combining cooking times and wood zones 97 Fig. 1. Relationship between various sulphate raw pulp factors and relative position within growth increments of black spruce and Douglas f ir 99 Fig. 2. Relationship between various Na-base bisulphite raw pulp factors and relative position within growth increments of black spruce and Douglas f ir 100 - X -ACKNOWLEDGMENTS The writer wishes to express his gratitude to Dr. J.W. Wilson, Professor, Faculty of Forestry, for his-guidance and supervision during planning, experimental phases and final reporting of this thesis, as well as his continuous encouragement during the past three years. The writer is also greatly indebted to Dr. R.W.. Wellwood, Professor and Dr. A. Kozak, Associate Professor, Faculty of Forestry; Dr. R. Branion, Assistant Professor, Department of Chemical Engineering; and Dr. R.W. Kennedy, Part-time Associate Professor, and Research Scientist, Forest Products Laboratory, Vancouver, B.C. , for reviewing this document. Thanks are also extended to Mr. J;E. Tasman, Head, Analysis and Testing Division, Pulp and Paper Research Institute of Canada, Pointe Claire, P.Q., for conducting the micro-scale pulping trials. The writer also gratefully acknowledges the financial support from the Faculty of Forestry, University of British Columbia, the Canada Department of Forestry and the National Research Council of Canada. Finally, my wife1s continuing encouragement is also appreciated. - 1 -INTRODUCTION I.tt has been shown that yields from chemical pulping of coniferous woods are correlated significantly with pulp and paper physical and chemical properties (2, 3, 33, 56, 82, 99). Other investigations have been carried out to determine coniferous wood pulp yields and properties by various pulping processes as regards differences between and within species, as well as between gross positions within individual trees (75). Pulp yields, under pulping conditions leaving 3 to 67, residual lignin, are shown to vary between and within species (12, 64, 75). For the same wood, pulp yields vary by wood zones (16, 71) and differ as regards tree growth environments (83). Similarly, pulp yields increase with age of tree for certain species (70). Some authors have found that pulp yield decreases with increa-sing wood specific gravity, while others report no or only slight correlation between these variables. As example, sulphite digestion of Norway spruce wood (Picea abies (Mill.) B.S.P.) with specific gravities between 0.35 and 0.54 indicated that pulp yield at the nominal 507, level decreased steadily with increasing specific gravity (47). In contrast, sulphate pulp yields with slash pine (Pinus e l l i o t i i Engelm.), loblolly pine (Pinus taeda L.) and longleaf pine (Pinus palustris Mill .) at the nominal 607, level showed that high specific gravity wood gives slightly higher pulp yields (16). In controlled experiments i t is always found that pulp yield is highly correlated with residual lignin content for various coniferous woods ( 6, 15, 57). - 2 -Pulp processing factors such as cooking liquor composition and liquor/wood ratio, rate of temperature rise and maximum temperature, pressure and time also greatly affect wood pulp yields (4,5,6,22,31,33, 35,48,53,84). This study was designed to keep wood and processing variables, such as cooking liquor composition, liquor to wood ratio, temperature rise and maximum temperature, as well as wood section size, constant, so as to achieve three purposes. These were to: a) Study raw pulp and carbohydrate yield patterns at different yield levels within black spruce (Picea mariana (Mill.) B.S.P.) and Douglas fir (Pseudotsuga menziesii (Mirb.) Franco.) heartwood growth increments. b) Contrast pulp yield variations between heartwood and sapwood growth increments taken from the same stem and pulped under the same conditions. c) Compare pulp yield variations between black spruce and Douglas f ir examined at the intra-incremental level. Meeting these objectives required development of micro-pulping and micro-analytical techniques. - 3 -REVIEW OF LITERATURE Pulping variations between and within coniferous species, wood zones and growth zones depend on morphological differences such as cell external dimensions, cell wall thickness and chemical composition, as well as cell wall molecular organization (21,37,39,45,55,67,76,95,96). These sources of variation seem to be related to environmental, physio-logical and genetic factors (45,100,101). A. Variation of Chemical Pulp Yields Among Coniferous Woods Various coniferous woods obviously differ in wood element size, element proportioning, chemical composition and morphological structures (59,96), a l l of which depend on heredity and growing conditions (100,101). The sulphite process is sensitive to properties of the starting material, wherein difficulties are introduced in pulping certain woods containing extractives which condense lignin, or that have penetration barriers (75). In contrast, sulphate pulping has no species restrictions, while acid bisulphite pulping above pH 4.0 is not restricted by wood extractives. Pulp yields at regular delignification levels largely relate to wood lignin and extractive contents, which differ between species. Cole, Zobel and Roberds (16) compared pulp yields and properties of three pine species by sampling an even-aged stand on a relatively uniform site. Their - 4 -results showed that under the same kraft pulping conditions, loblolly pine gave higher yields than slash pine, and that slash pine gave higher yields than longleaf pine for nominal 50 and 60% yield levels. Their explanation was that the lower yields for slash and longleaf pine were caused by higher extractive contents than contained in loblolly pine wood. Variation in chemical composition within species is known to be significantly affected by environmental factors. Cellulose content, which is highly correlated with chemical pulp yield, is subject to variation as regards site, geographic region and growth rate (101). Trees with higher latewood portion give slightly higher pulp yields because latewood usually contains more cellulose (66). According to one author (75), lower cellulose content in fast growing trees gives lower pulp yields compared to trees with regular growth rate. In general, trees with high cellulose and hemicellulose contents give higher pulp yields in a l l commercial pulping processes. B. Chemical Pulp Yield Differences Between Coniferous Wood Zones Pulp yields are significantly related to wood chemical com-position, which is known to vary in radial direction from the stem pith to periphery. Cellulose content was investigated by Wardrop (87) across wood zones of Monterey pine (Pinus radiata D. Don) and Douglas f ir Cross and Bevan cellulose increased rapidly in the first 10 to 15 years from the pith outward and then increased slowly thereafter. Similar results for Douglas f ir Cross and Bevan cellulose contents were also obtained by Kennedy - 5 -and Jaworsky (46). The lowest cellulose yields were found in the first 15-year section from pith, following which cellulose content fluctuated in succeeding years. Zobel and McElwee (101) reported a significant increase in alpha-cellulose and water-resistant carbohydrates from core-wood to mature wood of loblolly pine. The same species was examined as regards chemical composition by Stamm and Sanders (79), who showed that heartwood had considerably higher extractives and lower alpha-cellulose content than sapwood. At normal delignification levels, chemical pulps retain most of the cellulose portion so that pulp yields are expected to increase sig-nificantly from corewood to mature wood. In practice, yields from heartwood and sapwood are usually slightly different. This was confirmed for sulphite cooking of white spruce (Picea glauca (Moench.) Voss.) as 53 and 527,, respectively, for heartwood and sapwood (98) . For species con-taining heartwood extractives which are sulphite pulping inhibitors, raw pulp yield differences between wood zones can be remarkably different with those from heartwood being higher. As for sulphate pulping, heart-wood usually gives 2 to 37, lower yield than sapwood (75) . C. Coniferous Earlywood-Latewood Chemical Pulp Yields Variations across growth increments relate to morphological and chemical differences. In coniferous woods, the conspicuous difference between earlywood and latewood is that the former is comprised of thin-walled tracheids with large cell lumens, whereas the latter has tracheids with thicker walls and smaller lumens in radial direction. Studies on - 6 -heterogenety of the cell wall structure have shown that the P, and layers remain relatively constant in thickness from earlywood to latewood, whereas the layer which forms the bulk of the prosenchyma cell wall and has high cellulose content, significantly increases from earlywood to latewood (32). Similar patters have been found for specific gravity variations within increments of various coniferous woods (38,39,41). Comparisons of earlywood-latewood chemistry using data from the literature are shown in Table 1. In most cases, holocellulose is slightly higher and alpha-cellulose considerably higher in latewood while lignin content is significantly higher in the earlywood (1,32,36,58,60, 74,79). According to Table 1, data for different coniferous woods show higher extractives in earlywood (32,36,74). In optimum processing, pulp yields are directly correlated with holocellulose, and inversely related to wood lignin and extractive con-tents. During chemical pulping procedures, wood extractives are lost at various stages of cooking, but usually before advanced delignification (7). Quantitative analyses of earlywood and latewood pulp yields are rare and confusing. Data available from the literature for matched earlywood-latewood pulps made from coniferous woods are shown in Table 2. Quantitative differences in chemical pulp yields within growth zones were first reported in 1927 by Hagglund and Johnson (30). Three - 7 -different cooking times were used with separated earlywood and latewood of Norway spruce pulped by Ca-base sulphite. Their results showed 51.3, 52.5 and 50.0% yields for earlywood corresponding to 51.0, 52.2 and 47.9% yields for latewood, respectively. Thereby, earlywood seems to have given higher yield at these cooking levels. Further, Ca-base sulphite processing of southern pine (Pinus ap.) sapwood by de Montigny and Maass (20) showed 51.5 and 44.37, yield for earlywood and latewood, respectively. Yean and Goring (98) subdivided western hemlock (Tsuga heterophylla (Raf.) Sarg.) growth zones into three parts and pulped these by Na-base bisulphite. Their results showed that pulp yield increased slightly from earlywood to the transition zone, then to the latewood with values at 43, 44 and 457=, respectively. As for sulphate pulping, yields within growth zones have been reported by several authors for different species. Investigations have shown that earlywood may or may not give slightly higher yield than late-wood at commercial sulphate cooking levels. Watson and Dadswell (86) reported 51% yield for earlywood and 507. for latewood of Monterey pine. Ahlm and Leopold (1) obtained the opposite result with loblolly pine in that earlywood gave lower yield than latewood, with values corresponding to 46.0 and 48.1%,, respectively. This result was confirmed by Mcintosh (60), who obtained 45.6 and 47.17, yields, respectively, for earlywood and latewood from the same species. - 8 -MATERIALS AND METHODS A. Wood Sample Preparation Mature wood samples were taken at breast height from two coniferous trees. The black spruce (Picea mariana (Mill.) B.S.P.) sample originated from St. Michels des Saints, P.Q., while the Douglas f ir (Pseudotsuga  menziesii (Mirb.) Franco) sample was obtained from the University of British Columbia campus. Tree characteristics and details on growth increments examined are given in Table 3. Green specimen blocks of each wood were taken from sapwood and heartwood. Wood blocks were about 4-in. long, %-in. wide in tangential direction and 1-in. in radial direction. The wood blocks were submerged in water at room temperature, and a vacuum was applied for ten hours or until the blocks sank. Saturation provided a satisfactory softening pre-treatment for microtome sectioning. The growth increments chosen for examination were cut into serial tangential sections of 100 ^ 20 micron thickness, except where special thicknesses were required. Sections from one black spruce and one Douglas fir heartwood block were used for examining various sulphate pulp yield levels, while a second heartwood block of both species provided materials for Na-base bisulphite pulping, as well as specimens for intra-incremental specific - 9 -gravity and wood lignin determinations. Single sapwood blocks were used for the same purposes. B. Latewood Percentage Determinations Latewood percentage was determined for the growth increments studied according to Mork's definition for spruce ( 6 5 ) which states that latewood cells are those in which two times the double tangential wall thickness is equal to or greater than the radial lumen diameter. C. Wood Micro-specific Gravity and Micro-lignin Determinations 1 . Wood micro-specific gravity methods Wood specific gravity profiles were obtained for the growth in-crements studied. Ten positions were sampled within increments to represent earlywood, transition and latewood zones. Micro-specimens were sampled by punching out wet circular samples with a 3 / 1 6 - i n . diameter die. Two specimens were punched from the centre of each section sampled. Procedures for determining micro-specific gravity have been described in a previous report ( 1 3 ) . The calculation is based on extractive-free, oven-dry weight and green volume. 2 . Wood micro-lignin methods Lignin profiles across growth increments were determined by following the Johnson, Moore and Zank method ( 4 2 ) . Briefly, ten ml. of 257o acetyl bromide-acetic acid is used to digest each extractive-free wood sample at 7 0 * l^C for 3 0 min. The mixture is cooled in cold - 10 -water and transferred to a 200 ml volumetric flask containing 9 ml of 2 M sodium hydroxide and 50 ml of acetic acid. One ml of 7.5 M hydroxylamine hydrochloride is then added and the mixture is diluted to 200 ml with acetic acid. The prepared solution is immediately measured for absorbance at 282 mu. Wood lignin absorptivity depends on species and growth zone as shown in Table 4. . Samples were taken from ten extractive-free wood sections for each increment. Specimens were punched from sections by the above mentioned 3/16-in. die and dried in vacuum over P^O a^t room temperature. Wood sample weights of 15.00 - 1 mg for earlywood and 20.00 - 1 mg for late-wood were obtained on a Cahn electrobalance having sensitivity of 0.01 mg and contained in a desiccator. Each position required one determination (95). D. Determining Micro-pulp Yields 1. Micro-pulping procedures a. Wood sample preparation and pulping Extractive-free wood specimens were prepared by treating the entire lot of specimens in sequence with diethyl ether, ethyl alcohol, and hot disti l led water as described in a previous report (13). Sections from each heartwood increment were grouped as consecutive sets of three and randomly assigned into three groups for the three cooking levels to be examined. Each group contained 10 sections rep-resenting 10 positions across the increment. For sapwood, two groups of - 11 -10 positions were used for each increment for a single level of sulphate pulping and another similar set for a single Na-base bisulphite cook. Each wood section was divided into two equal pieces to provide two re-plications. The segmented extractive-free wood samples were vacuum dried over P^ O^ at room temperature for three days to obtain constant weight. They were then rapidly moved to a desiccator, which was entered into the desiccated glove box containing the Cahn electrobalance. Weighings were done at the 100 mg range which has sensitivity of 0.01 mg. Each pair of wood specimens was randomly positioned on a 5 x 15-in., 150-mesh stainless steel screen which was rolled to less than 5/8-in. diameter. Each rolled set of wood samples was assigned to a given pulping procedure as shown in Table 5. For each pulping process three rolls contained materials for 10 positions, while two further rolls each represented 20 positions. Each ro l l was made up to equal wood weight by adding additional wood sections, which gave a constant liquor to wood ratio. The packages of wood samples were conditioned in a humidity chamber for two days under 80°F dry bulb temperature and 2°F wet bulb depression which provided 90% relative humidity. Moisture contents of 17.9 to 18.1%. were obtained as determined by taking weight differences before and after conditioning. The moisture content of each rol l is shown in Table 5. The wood sample rolls were immediately sealed in polyethylene bags to avoid - 12 -moisture change before cooking. The micro-scale sulphate and Na-base bisulphite pulps were produced by the Pulp and Paper Research Institute of Canada, Pointe Claire, P.Q. A rocking electrically heated cooker holding six bombs with 5/8-in. internal diameter and 5- in. length was used. Two cooks were conducted under conditions shown in Table.6 with different times at maximum temp-erature to obtain yield levels desired. At prescribed times, the bombs were removed from the block and quenched in cool water. Liquors were drained away and the wrapped' parcels were placed in 200 ml beakers with distilled water. After this, the wash water was clean, indicating removal of a l l cooking liquor. Again the packages were sealed in polyethylene and returned to Vancouver for further processing. b. Pulp yields, residual lignin and pulp carbohydrate yields The pulped wood segments were air-dried, then packages were opened and individual samples were removed and stored in vials. Again the samples were dried under vacuum over ^2^5 a n c * w efgbed i- n the oven-dry condition. Per cent pulp yields were calculated based on the in i t ia l extractive-free water-free weight. Residual lignins were determined for the cooked micro-samples by a modified Johnson, Moore and Zank technique (42). Carbohydrate yields were obtained by subtracting residual lignin content based on wood from average pulp yield for each position. - 13 -2. Development of procedures a. Micro-pulp yield As noted, the pulping procedures kept a l l cooking variables con-stant except time at maximum temperature so that pulp yield variations within and between growth zones could be compared. In order to evaluate wood variables which might affect micro-pulp yield and composition, a series of preliminary experiments were conducted to examine micro-pulping variables. These included study of effects of wood section thickness, screen mesh size and wood sample position in packages. In addition, early experiments provided information for calculating replication to ensure statistical validity, and allowed proper setting of time at maximum temperature to obtain desired yields. (1). Effect of wood section thickness on pulp yield For sulphate pulping of Norway spruce and Scots pine (Pinus sylvestris L.) to 45 to 557c yield level, i . e . , 4 to 57, residual lignin, Colombo et a l . (17) observed that wood chip thicknesses between 3 and 8 mm did not cause differences in delignification degree and screened pulp yield at constant cooking time. Chip thicknesses above 8 mm, however, sig-nificantly affected screened pulp yields and residual lignin contents. The effect of wood section thickness on pulp yields was studied in a preliminary trial by using various thicknesses of sections randomly sampled from black spruce and Douglas fir earlywood and latewood and cooked in both sulphate and Na-base bisulphite liquors. The section thicknesses were 50 - 10, 110 * 10, 210 * 10 and 410 - 10 microns. Specimens of - 14 -d i f f e r e n t thickness were randomly positioned on a 150-mesh screen, wrapped as packages and pulped to 50% target y i e l d . The analysis of variance for sulphate and Na-base b i s u l p h i t e pulps i n Table 7 shows that pulp y i e l d s were not affe c t e d by section thicknesses from 50 to 410 microns. (2) . E f f e c t of screen mesh size on pulp y i e l d In order to determine the e f f e c t of d i f f e r e n t screen mesh sizes on pulp y i e l d s , an experiment was designed to examine mesh sizes of 40, 100 and 150 when containing black spruce wood sections (100 ^  20 microns) subjected to sulphate cooking. Results of analysis i n Table 8 show that these mesh sizes had no s i g n i f i c a n t e f f e c t on pulp y i e l d . (3) . E f f e c t of sample p o s i t i o n on screen In t h i s experiment, 100 ^  20 microns thickness wood sections were randomly positioned on a 150-mesh 5 x 15-in. screen. The between positi o n s e f f e c t (depth i n package) and within p o s i t i o n (edge vs. central position) were studied with black spruce and Douglas f i r wood sections cooked i n both sulphate and Na-base b i s u l p h i t e to the 55 ^ - 5% y i e l d l e v e l . Two paired adjacent sections from earlywood, t r a n s i t i o n wood and latewood of an increment were randomly sampled, divided into four sub-sections and randomly positioned on the screen. Residual increment sections were used to make up wood volume. - 15 -Analysis of variance was used to test effects of different screen position on pulp yields. The results in Table 9 show that between position effects within a package were non-significant, except for Douglas f ir earlywood and transition zone. These exceptions might have been caused by wood variation between two adjacent sections rather than the between position effect, because at the 55 -^ 57» yield level Douglas f ir pulp yields within increment increased markedly from earlywood to the in i t ia l latewood then decreased gradually to the end of the growth zone. As a further part of the trial each section was divided into four sub-sections and two of these were randomly positioned at screen edges and the other two were placed in central positions. The combined data for species and pulping processes were subjected to analysis of variance with results shown in Table 10. The effect of within position and its interaction with species and pulping process did not significantly affect pulp yield. (4). Determination of replication number An experimental series was carried out to determine suitable replication numbers by both pulping procedures for each position examined within a growth increment. As described in the previous experiments, two paired randomly selected adjacent sections from earlywood, transition zone and latewood of black spruce and Douglas fir were cut into eight sub-sections for each of the three positions within growth zones. The wood samples were cooked by both sulphate and Na-base bisulphite to 55 * 57. yield. - 16 -The replication number for various positions within growth zone was calculated by using the following equation (80): N = t x s /d Where: N » replication number t = Student's t-value at n-1 degrees of freedom and 957. probability level s = sample variance d = ( mean x 0.0p)/2, 57. allowable error (P) being used. Yield replication numbers calculated for species and pulping processes are shown in Table 11. The average calculated number is 0.95, or 1. By using two replications, the allowable error (P) was reduced to 3%. b. Residual micro-lignin The ultraviolet spectrophotometrie absorbance measurement for wood pulp residual lignin determinations was originally developed by Johnson et. a_l (42) for micro-wood samples. They observed difficulties when applying their method to pulps. The original method was re-examined and used for determining lignification patterns within coniferous wood growth zones by Wu and Wilson (96). An application of the method to wood pulp residual lignins was reported recently by Marton (61), who applied a correction factor to compensate for background absorbance at zero kappa number, which was claimed to give precision of ^ 2%. The Uohnson et. al. (42) procedure was followed in the present study for estimating pulp residual lignin, except that some modifications were - 17 -included. Briefly, a micro-pulp sample of known weight (about 30 mg) was placed in a 30 ml reaction tube with notched glass stopper. Ten ml of freshly distilled 25% acetyl bromide-acetic acid reagent was added. The reaction was done at 70 1°C for 30 min with gentle swirling at 10 min intervals. The digested pulp solution was immed-iately cooled to 13°C in a cold water bath for 10 -^ 2 min. The cooled solution was then transferred to a 200 ml volumetric flask into which had been placed 9 ml of 2 M sodium hydroxide and 50 ml of acetic acid. Five to 10 ml of additional acetic acid was used for completing the transfer. Then 1 ml of 7.5 M hydroxylamine hydrochloride was added to the volumetric flask and the contents were diluted to 200 ml with acetic acid. After storing the solution at 20°C for 71 ^ 1 hr, the absorbance was measured at maximum peak of 282 mu on a Spectronic 505 instrument. Lignin content based on moisture-free pulp weight was computed as follows : Lignin % = (Sample absorbance - Blank absorbance) X Liters X 100 Absorptivity X Sample weight (g ) The blank absorbance was measured for a solution prepared by the same procedures except omitting the pulp sample. Pulp residual lignin absorptivities were found to depend on species and pulping processes. The absorptivities were calculated on the basis of residual lignin content. Absorbtivity = Absorbancex Liters  Water-free pulp weight (g ) x Fractional residual lignin - 18 -Where : fractional residual l ignin = 0.15 x Micro-kappa number (9). The average residual l ignin absorptivities for various pulps and associated standard deviations are shown in Table 4. (1). Sample weight A proper absorbance between 0.2 to 0.8 for pulp solutions requires 0. 6 to 6.0 mg l ignin per 100 ml di lut ion. In these experiments, the pulp sample weight selected depended on cooking time and process. Thereby, 25 to 30 mg of moisture-free pulp was needed for high yie ld samples, 1. e. 157, residual l ign in , and 40 to 50 mg for commercial paper pulp yield levels containing about 57o residual l ign in . Marton (61) used 25 to 35 mg for the commercial yield leve l , but only diluted to a total of 100 ml instead of the 200 ml total di lut ion. The relationship of different dilution volumes and sample size was examined by the original authors (42), who showed that the 100 ml, 200 ml and 1000 ml acetic acid dilutions were not much different for Douglas f i r wood samples. Marton (61) pointed out that pulp samples could be reduced to 5 - 10 mg by lowering the f inal di lut ion volume to 10 - 25 ml, and reducing the amount of reagent accordingly. In these experiments, the digested l ignin solution was diluted to 200 ml by reagent grade acetic acid. For preparation of samples before digestion, Johnson e_t a_l (42) ground wood samples in a micro Wiley mi l l to pass an 80-mesh screen. The wood meal was stored in a controlled humidity chamber unt i l equ i l i -brium was reached. A similar treatment was used by Wu (95). For - 1 9 -treatment of wood pulps, Mar ton ( 6 1 ) dried samples in a 1 1 0 C oven, ground these to pass through a 20-mesh screen, then stored in a desiccator over ?2^ 5* * n t ' l e P r e s e n t experiments, air-dry samples, combining replications for each position, were cut by scissors into l x l mm squares. The samples were dried in vacuum over P^ *-^  f ° r three days to obtain constant weight. Weighing was conducted by using a Cahn electrobalance of 5 0 mg range with 0 . 0 0 5 mg sensitivity housed in a desiccator. ( 2 ) . Digestion time and pulp solubility Wood samples were almost completely dissolved in 3 0 min cooking as found by Johnson et al. ( 4 2 ) and Wu ( 9 5 ) . Further study by Wu ( 9 5 ) indicated that cooking time of 3 0 * 5 min only caused * 1.5% difference in relative lignin content. As regards wood pulp solubility, Marton ( 6 1 ) showed that solubility of pulp in the digesting reagent depends on the degree of delignification. Coniferous pulps having more than 3 . 5 7 . residual lignin were completely soluble in 3 0 min, whereas bleached pulps were difficult to completely dissolve, except for bleached sulphate pine pulp. A similar observation was made in the present study, in that wood pulp solubility depended on the pulping process. After 3 0 min of digestion, sulphate pulps could be completely dissolved at a l l levels of delignif ication, but both Na-base bisulphite pulps of 5 0 ^ 57o yield, i .e . 57o residual lignin, were incompletely solubilized. With these an insoluble residue remained even after digestion time was extended to 6 0 min. ( 3 ) . Elapsed time and relative lignin content It had been stated that absorbance of wood lignin solutions is con-- 20 -stant for certain periods up to 5 hr after dilution for Douglas fir (42), and 24 hr for amabilis fir (Abies amabilis (Dougl.) Forbes) with solutions stored at 12 1°C (95). In early experiments, i t was shown that solution absorbance changed considerably after dilution. In order to study the effect of storage time, high yield Douglas fir sulphate pulp and black spruce Na-base bisulphite pulp lignin solutions were prepared and absorbances were measured at different time intervals after dilution. The solutions were stored and maintained at 20 ^ 1°C. Results are shown in Table 12. An obvious difference in absorbance readings was observed between the two pulp solutions. The Douglas f ir sulphate pulp solution significantly increased in absorbance during the first 20 hr of storage; whereas the black spruce bisulphite pulp solution apparently decreased absorbance during the first 20 hr of storage, which was accompanied by a shift in maximum peak from 270 mu to 282 mu within the first 10 hr. The increasing absorbance with increasing storage time of the Douglas f ir sulphate pulp solution might be due to further hydrolysis of residual lignin macro-molecules. Absorption behaviour of the black spruce bisulphite pulp solution seems complicated, although equilibrium + in absorbance was approached after about 71- 1 hr of storage. In this study, pulp solution absorbances were read after storage at 20 ^ 1°C for 71- 1 hr following dilution, since these values gave more stable absorbance readings. The proper time for making readings is by no means settled, nor are reasons for time-dependent changes in absorbance understood. RESULTS Wood lignin contents and specific gravities across black spruce Growth Increments No.31 (heartwood) and No.47 (sapwood) and Douglas f ir Increments No.30 (heartwood) and No.57 (sapwood) are given in Tables 13 and 14, respectively. Raw pulp yields, residual lignin contents and carbohydrate yields across growth increments examined at different cooking levels by two pulping processes and for two wood species are presented in Tables 15 to 22. The relationship of raw pulp yields and pulp carbohydrate yields with relative position within growth increments for black spruce and Douglas fir are shown graphically as Fig. 1 and 2 for sulphate and Na-base bisulphite cooking, respectively. Data were fitted to the model : ln Y = b + b.X + b„X2 + b„X3 o 1 z 3 Where : Y = raw pulp yields or pulp carbohydrate yields X = relative position within growth increment from beginning of earlywood A. Intra-incremental Micro-specific Gravities And Wood Micro-lignins Micro-specific gravity profiles within increments showed minimum values in earlywood, then increased abruptly at the transition zone and approached a maximum in the early latewood (Figs. 1 and 2). From Table 14, specific gravity for black spruce had average values of 0.491 (0.278 to 0.693) and 0.488 (0.255 to 0.734) for Increments No.31 and No.47, respectively. Douglas f ir had average specific gravities of - 22 -0. 473 (0.214 to 0.801) for Increment No.30 and 0.490 (0.237 to 0.700) for Increment No.57. Curvilinear regressions of the relationship between specific gravity and relative position within growth increments are shown in Table 23. The relationship of specific gravity and raw pulp yields within growth increments are shown graphically in Fig. 1 and 2. In Table 13 the average lignin contents are recorded as 23.56%, (20.81 to 26.57%) for black spruce increment No.31 and 23.26% (21.10 to 26.19%,) for Increment No.47. The average lignin content of Douglas f ir Increment No.30 was 24.12% (21.70 to 27.47%) and 26.16% (22.64 to 30.45%) for Increment No.57. The curvilinear regressions given in Table 24 show that wood lignin contents are highly significantly correlated with relative position within growth increments. B. Raw Pulp Yields Average raw pulp yields differences for different cooking times, relative positions within growth increment, pulping process, wood zones and wood species are shown in Tables 15 to 22. 1. Within growth increment a. Raw pulp yields Results at various cooking levels for black spruce and Douglas f ir - 23 -heartwood growth in Fig. 1 and 2. was increased. The curvilinear regressions between raw pulp yields and relative position within increments are shown in Tables 25 and 26 for sulphate and Na-base bisulphite pulping processes, respectively. In sulphate cooking of heartwood increments No.31 for black spruce and No.30 for Douglas f i r , the three different yield patterns illustrate that the position within increments at which yield was a maximum changed slightly between different yield levels. As shown in F i g . l , at 3 min cooking time at maximum temperature the peak yield was at about the 40% relative position within increment, but was shifted to the 50 to 55%, relative position when maximum cooking time was increased to 12 min. Further cooking to 32 min moved the yield maximum to the 80% relative position. For sapwood increments of black spruce (No. 47) and Douglas fir (No. 57) maximum yields were at about 60%, relative position for the medium cooking time. Yields decreased toward earlywood and latewood for Douglas f i r , but only slightly toward latewood and sharply toward earlywood for black spruce (Fig.l) . Table 25 shows curvilinear regressions between sulphate raw pulp yields and relative position within increment. The correlations are increments, as well as for pulping processes are shown Pulp yields decreased considerably as cooking time Hereafter referred to as min max. - 24 -highly significant for different yield levels of heartwood increments and for sapwood increments, except that the black spruce high yield level (3 min max.) was not significantly correlated. For Na-base bisulphite pulping, the three cooking levels for raw pulp yields within heartwood increments showed similar behaviour for black spruce and Douglas fir (Fig.2). At high yield levels, i .e . 43 and 53 min max cooking time, raw pulp yields were slightly increased from earlywood to the 30 to 407. relative position, then abruptly decreased in the transition zone and almost remained constant within latewood. As for intermediate yield cooks, i .e . , 240 min max cooking time, heartwood and sapwood increments showed similar behaviour in tha.t pulp yields were sharply increased from the earlywood in i t ia l low to a maximum at the transition zone of 40 to 607, relative position, then abruptly decreased toward the latewood zone. Pulp yields within latewood zones were more or less constant. Curvilinear regressions of Na-base bisulphite raw pulp yields and relative position within growth increments of black spruce and Douglas fir are given in Table 26. At high yield levels, i .e . 43 and 53 min max cooking time, raw pulp yields were either significantly or highly sig-nificantly correlated with position for both black spruce Increment No.31 and Douglas fir Increment No.57, where as the intermediate yield levels, i .e. 240 min max cooking time for heartwood and sapwood increments (No.47 and No.57 for black spruce and Douglas f i r , respectively) were not sig-nificantly correlated. - 25 -In addition, the variation in pulp yield between earlywood and latewood was subjected to analysis of variance for each cooking level. These results are tabulated in Table 2 for comparison with various processes and yield levels from the literature. b. Residual lignin contents Residual lignins were calculated on water-free pulp and water-free wood basis as shown in Tables 15, 16 and Tables 17, 18 for black spruce and Douglas fir sulphate cooking, respectively. Similarly, Tables 19, 20 and Tables 21, 22 record values for black spruce and Douglas fir Na-base bisulphite cooking. The data from these tables show that the residual lignin distribution within increments are different between species and pulping processes. Black spruce sulphate pulp cooked for 3 and 12 min max gave maximum residual lignin based on over-dry pulp in earlywood at about the 207=. relative position. This greatly decreased to the transition zone at 607, relative position, then increased to the end of the growth increment. Douglas f ir high-yield sulphate cooking (3 min max) showed the highest residual lignin content in earlywood, which sharply decreased to the transition zone, then remained constant through the latewood. At 12 min max cooking level, the residual lignin peak was in the transition zone and decreased toward the earlywood and latewood (Table 17, 18). The lowest yield level (32 min max) gave a very low, essentially equal residual lignin content throughout the whole increment (Table 17). Residual lignin contents within increments showed different - 2 6 -behaviour between species. Black spruce heartwood pulps from Increment No.31 at high-yield levels, i .e . 4 3 and 5 3 min max, gave residual lignins which decreased from earlywood to the transition zone, and then increased toward the latewood. A similar pattern was found when cooking to 2 4 0 min max, in that residual lignin was s t i l l at a minimum level in the transition zone (Table 1 9 ) . The sapwood Increment No.47 cooked to 2 4 0 min max showed slightly higher residual lignin content in the transition zone (Table 2 0 ) . When Douglas f ir heartwood Increment No.30 was cooked to high-yield levels, i .e. 4 3 and 5 3 min max, the highest residual lignin contents (based on water-free pulp) were in the earlywood and then abruptly decreased toward the transition zone with minimum at the 6 0 to 807c relative position after which lignin increased through latewood (Table 2 1 ) . At the intermediate yield level, i .e. 2 4 0 min max, the behaviour was identical for heartwood (No.30) and sapwood (No.57) increments in that residual lignin contents sharply decreased from earlywood to the transition zone then slightly increased in the latewood zone (Tables 2 1 and 2 2 ) . In general, residual lignin contents based on oven-dry pulp were directly related to the different raw pulp yield levels and pulping process used. At the commercial paper pulp yield level ( 4 5 to 507o raw pulp yeild) residual lignin contents mostly remained constant through the whole increment or were only slightly higher at the transition zone. Earlywood and latewood residual lignin contents based on water-free wood were tested by analysis of variance for each cooking level examined. The earlywood and latewood residual lignin contents are tabulated in - 27 -Table 2 for comparison with various pulp yield levels, processes and species from the literature. c. Pulp carbohydrate yields Pulp carbohydrate yields were obtained by subtracting the residual lignin content from the average raw pulp yield, with both based on water-free wood. This was done for each position sampled within growth increments. Results are tabulated in Tables 15 to 22 and plotted in Figs. 1 and 2 for sulphate and Na-base bisulphite pulps, respectively. The carbohydrate yield patterns within increments have similar shapes to those of average raw pulp yields, except at high-yield levels which show a slight shift of maxima toward the in i t ia l latewood (Figs. 1 and 2). Curvilinear regression of sulphate pulp carbohydrate yield and relative position within growth increments of black spruce and Douglas fir are given in Table 27. The correlations are highly significant for different yield levels of heartwood and for sapwood increments of both species examined. Table 28 shows curvilinear regressions between Na-base bisulphite pulp carbohydrate yields and relative position within growth increments. Black spruce and Douglas fir pulp carbohydrate yields are either highly significantly or significantly correlated with relative position for heartwood and sapwood increments except for the black spruce sapwood increment. 2. Between wood zones In order to test the raw pulp yields and pulp chemical composition between heartwood and sapwood increments, these wood sections were pulped - 28 -in the same set for each process. As shown in Table 5, sulphate pulps were cooked to 12 min max and Na-base bisulphite pulps were cooked to 240 min max. The results are plotted as part of Figs. 1 and 2. These graphs compare directly pulp and carbohydrate yields between heart-wood and sapwood increments of the same stems. Black spruce and Douglas fir raw pulp yields, residual lignin con-tents and pulp carbohydrate yields based on extractive-free water-free wood were further analysed for comparisons between wood zones. These analyses are shown in Tables 29 and 30 for sulphate and Na-base bisulphite pulps. For sulphate pulping, the results of analysis of variance for 12 min max cooking of heartwood and sapwood increments of black spruce and Douglas fir are shown in Tables 29A, 29B, and 29C. These correspond to raw pulp yields, residual lignins and carbohydrate yields based on extractive-free water-free wood as related to intra-incremental position. The combined raw pulp yields for black spruce and Douglas fir data are 59.22% and 57.89% corresponding to heartwood and sapwood increments respectively. For separate species, black spruce heartwood Increment Hb.31 gave 57.44% and sapwood Increment No.47 gave 57.93%; Douglas f ir heartwood increment No.30 was 60.99%. and sapwood Increment No.57 was 57.86%,. The analysis of variance in Table 29A shows that combination of heartwood and sapwood data for two species is not significant, but that the species X wood zone interaction is significant. - 29 -Pulp residual lignin content, based on extractive-free water-free wood for the two species combinations gave 3.69% for heartwood and 3.66%, for sapwood. For single species, black spruce heartwood Increment No.31 gave 4.29%, and sapwood Increment No.47 gave 3.37%; Douglas f ir heartwood Increment No.47 gave 3.08%, and sapwood Increment No.57 was 3.96%. The analysis of variance in Table 29B shows that combined data for the two species heartwood and sapwood (wood zone) variation is non-significant, but that the species x wood zone interaction is highly significant. The wood zone variation of pulp carbohydrate yield for combined species based on extractive-free water-free wood was 55.48%, for heartwood and 54.12%, for sapwood. Further, black spruce heartwood Increment No.31 yield was 53.06% and sapwood Increment No.47 was 54.56%,; Douglas fir heartwood Increment No. 30 was 57.91%, and sapwood Increment No. 57 was 53.69%>. The analysis of variance in Table 29C shows that the combined species wood zone variation is non-significant, but that the species x wood zone interation is highly significant. For Na-base bisulphite pulping, the analysis of variance for 240 min max cooking for heartwood and sapwood increments for black spruce and Douglas fir are given in Tables 30A , 30B and 30C. These correspond to pulp yields, residual lignin contents and carbohydrate yields based on extractive-free water-free wood as related to intra-incremental position. Raw pulp yields for combination of the species examined were 53.80%, for heartwood and 55.73%, for sapwood. For single species, black spruce - 3 0 -heartwood Increment No.31 yield was 4 6 . 7 5 7 , and sapwood Increment No.47 was 5 3 . 4 2 7 ° ; similarly values of 6 0 . 8 5 7 , and 5 8 . 0 5 7 , correspond to Douglas fir heartwood Increment No.30 and sapwood Increment No .57 . The analysis of variance in Table 3 0 A shows that the difference in raw pulp yields between the combined species heartwood and sapwood . increments is not significant, whereas variation of the species x wood zone interaction is highly significant. Residual lignin content the combination of both species was 3 . 2 6 7 o for heartwood and 2 . 457o for sapwood. The value for black spruce heart-wood Increment No.31 was 2.13% and sapwood Increment No.47 was 1 . 6 0 7 c , ; while 3 . 7 8 7 , and 3 . 3 0 7 , correspond to Douglas fir heartwood Increment No.30 and sapwood Increment No .57 , respectively. Analysis of variance in Table 3 0 B shows that neither differences between wood zones nor the species x wood zone interation are significant. Pulp carbohydrate yields for the two species combined were 5 0 . 5 0 7 , for heartwood increments and 5 3 . 2 9 % for sapwood increments. For single species, black spruce heartwood Increment No.31 yield was 4 4 . 0 2 7 c and sapwood Increment No.47 was 5 1 . 8 2 7 , ; Douglas fir had 5 6 . 9 7 7 o for heartwood Increment No.30 and 5 4 . 7 5 7 , for sapwood Increment No .57 . The analysis of variance in Table 3 0 C shows that the difference in pulp carbohydrate yields between the wood zones of both species combined as well as zone interaction, is highly significant. In summary, raw pulp yields, residual lignin contents and pulp carbohydrate yields based on extractive-free water-free wood were not - 31 -s i g n i f i c a n t l y d i f f e r e n t between heartwood and sapwood increments for the combined black spruce and Douglas f i r using both pulping processes. However, pulp carbohydrate y i e l d for Na-base b i s u l p h i t e pulping of sapwood increments was s i g n i f i c a n t l y higher than that of heartwood increments. Also the species X wood zone i n t e r a c t i o n was s i g n i f i c a n t to highly s i g -n i f i c a n t for a l l factors except Na-base b i s u l p h i t e r e s i d u a l l i g n i n contents. 3. Between species Species v a r i a t i o n s were tested by analyzing various cooking l e v e l s and wood zone combinations. For each process, raw pulp y i e l d s , pulp r e s i d u a l l i g n i n s and carbohydrate y i e l d s based on ext r a c t i v e - f r e e water-free wood were compated separately for black spruce and Douglas f i r . Results are shown i n Tables 31 and 32 for sulphate and Na-base b i s u l p h i t e processes r e s p e c t i v e l y . For sulphate pulping, analyses of variance for species var i a t i o n s are shown i n Tables 31A, 3lB and 31C for raw pulp y i e l d s , r e sidual l i g n i n s and pulp carbohydrate y i e l d s based on ext r a c t i v e - f r e e water-free wood. The average raw pulp y i e l d s for a l l cooking l e v e l s and wood zones were 55.82% for black spruce and 58.34% for Douglas f i r . Combining species growth zone vari a t i o n s gave earlywood and latewood at 57.24% and 56.82% re s p e c t i v e l y . Further, the species X growth zone i n t e r a c t i o n shows that black spruce earlywood and latewood are 53.65 and 56.10%, while 58.90 and 57.50%, correspond to Douglas f i r earlywood and latewood. Table 31A shows that the raw pulp y i e l d v a r i a t i o n , between the two species, two growth zones and species X growth zone int e r a c t i o n s are not s i g n i f i c a n t l y - 32 -different. Average residual lignin contents were 3.587, for black spruce and 3.737, for Douglas f i r . Earlywood had 4.077. and latewood 3.007, lignin. The species X growth zone interation shows that black spruce had average residual lignin contents of 3.97 and 2.947, for earlywood and late-wood, while Douglas f ir had 4.17 and 3.067»,respectively. The analysis Of variance for pulp residual lignin content shown in Table 3lB indicates that earlywood had significantly higher residual lignin content than latewood; but species, as well as the species X growth zone interaction, are not significant. Average pulp carbohydrate yields between species were 52;21 and 54.657c for black spruce and Douglas f i r . Growth zone variations for com-bined species data between earlywood and latewood corresponded to 53.20 and 53.807c. The species X growth zone interactions were 51.64 and 53.177, for black spruce earlywood and latewood; while Douglas fir earlywood and latewood gave 54.82 and 54.397,. The analysis of variance of Table 31C shows that Douglas f ir gave significantly higher carbohydrate yield than black spruce, whereas the species X growth zone interaction was not sig-nificant. As for Na-base bisulphite pulping, an analysis of variance was also conducted by combining a l l cooking levels and wood zones for raw pulp yields, pulp residual lignins and carbohydrate yields based on extractive-free water-free wood as shown in Tables 32A, 32B and 32C. - 33 -The average raw pulp data for a l l cooking levels and wood zones for both species combined show variations of 65.73 and 61.95% for early-wood and latewood. The species X growth zone interaction showed that black spruce earlywood and latewood yields correspond to 60.46 and 55.40%; while Douglas f ir gave 71.66 and 62.27% for earlywood and latewood, res-pectively. The analysis of variance in Table 32A indicates that Douglas fir raw pulp yield was highly significantly different than that for black spruce, whereas growth zone variation and the species X growth zone interaction were not significant. Species variations on pulp residual lignin were 6.26% for black spruce and 7.40% for Douglas f i r . For combined species data, values of 7.53 and 5.60%, were obtained for earlywood and latewood. The species X growth zone interaction shows that black spruce earlywood and latewood correspond to 6.86 and 5.02%; while Douglas fir was 8.30 and 6.06%, for earlywood and latewood. Further analysis of variance in Table 32B indicates that species, combined data for growth zones and the species X growth zone interaction are not significant. For Na-base bisulphite pulping, carbohydrate yields of 52.56 and 62.61%, were obtained for black spruce and Douglas f i r . Growth zone variations for both species combined gave earlywood and latewood at 58.30 and 56.32%,. The species X growth zone interaction for black spruce was 53.61 and 50.36%, for earlywood and latewood; while Douglas fir had 63.57 and 61.17%. The analysis of variance in Table 32C shows that Douglas fir had significantly higher pulp carbohydrate yield than black spruce, whereas the variation of growth zone and species X growth zone - 34 -interaction were not significantly different. - 35 -DISCUSSION Coniferous woods vary within growth increments as regards anatomical structure, physical properties (21,38,39,41) and chemical composition (32,93,95,96). Variation in cell wall structure within increments affects not only wood properties and pulp and paper strength properties (34,41,43,86), but may also influence the movement of cooking liquors from cell lumens through pits to other cell cavities and diffusion rates from cell cavities to different layers of cell walls. The chemical differences within growth increments may affect the accessibility of cooking liquor, delignification rate and carbohydrate degradation. A. Variation Within Growth Increments 1. Morphology and pulp yields Coniferous woods usually have large diameter tracheids with thin walls in earlywood and narrower radial diameter tracheids with thicker walls in latewood. Transition from the earlywood to latewood zone may be abrupt or gradual depending on species (10,21). This cyclic growth pattern has been evaluated in relation to environmental, physiological and ecotypic factors (92). Specific gravity variation within a growth increment is directly related to cell lumen dimensions, wall thickness and possibly wall density. In general, specific gravity increases from earlywood to latewood about - 36 -two to three times in a gradual or abrupt way depending on the charact-eristics of the transition zone in a particular wood. In this experiment, wood tangential section thicknesses were 100 20 microns, or about 2 cell widths for earlywood and 3 to 4 cell widths for latewood specimens. The moisture contents at beginning of cooking were below the fibre saturation point (Table 5); thus, the cooking liquor penetration of a ir- f i l led wood was dominated by capillary rise and subsequently water vapor diffusion (78). Water vapor diffuses into the adjacent a ir- f i l led cell lumens through pit membrane pores then condenses on the cell wall and allows further penetration by capillary rise. Gas diffusion may be faster in earlywood structures than in latewood due to larger lumens and possibly more perforated pit structures (75). However, capillary rise is also very fast which may account for about 90% of the liquid penetration (78). Since latewood has considerably smaller lumens than those of earlywood, the capillary force in latewood is about 10 times greater than in earlywood (40). Therefore, i t is logical to propose that latewood is the first tissue to be attacked by the pulping liquor during first stages of cooking wood at in i t ia l moisture contents below the fibre saturation point. Penetration of the cell wall by pulping media was considered by Lange (49), who proposed that the pit structure periphery provided the point where pulping media contact the middle lamella, so that the in i t ia l attack should be in the middle lamella. In contrast, electron-microscopy studies by Wardrop et. al (91) using Coppick and Fowler staining techniques - 37 -suggest that pulping media do not move into the middle lamella through pit membranes, but rather by passing through different cell wall layers. This mechanism, i f correct, must relate pulp yield to variations in cell wall layer thicknesses, permeabilities and chemical composition. Studying porosities of different cell wall layers has shown that the S^  layer, primary wall and middle lamella are regions of relatively high porosity, whereas the has relatively high packing density (50,51,52). This was further confirmed by Walchi (85), who determined permeability of different cell wall layers by Congo red absorption. He found that the number of capillaries which the dye could penetrate was greater in S^  and S^  layers than in the S^ - Heterocapillary systems were investigated by Frey-Wyssling and Mitrakos (26), who found that capillaries between micro-fibrils and within microfibrils were larger than 1001 and 10A, respectively. Thereby, large molecular items can only penetrate or be discharged through the large capillaries between microfibrils. As regards diffusion of pulping media into the cell wall, Wardrop and Wardrop et. al_ (88,89,91) state that such liquids pass in i t ia l ly into the relatively porous S^  layer, then into the lightly lignified layer, then forward to the S^  layer where cooking media contact highly porous, lignified regions. By further progress, the cooking liquor approaches the primary wall and middle lamella which are more highly lignified and probably less readily penetrated. As delignification proceeds continuously across outer parts of the cell wall, ions must diffuse further from the cell lumen through the secondary wall. Therefore, the carbohydrate-rich secondary wall is subjected to exposure for the longest time to the most concentrated solution, which may cause considerable carbohydrate - 38 -degradation during pulping. As noted, cell wall thickness increases from earlywood to late-wood. The S£ layer accounts for most of the change, while other layers remain mostly unchanged throughout the whole increment. Therefore, the thinnest S2 layer exists in earlywood, while the thickest is in late-wood. As shown in Fig. 2, Na-base bisulphite pulp yields within incre-ments of both black spruce and Douglas fir were significantly higher in the earlywood zone than in latewood. The effect is more pronounced with high yield cooks. This may be caused by greater exposure of the thicker latewood S£ layer to the pulping medium and hence more carbohydrate degradation during the in i t ia l stages of pulping. 2. Delignification and residual lignin contents The variation of lignin content within growth increments has been investigated. Earlier data from Ritter and Fleck (74), Bailey (8) and Hata (36), as well as recent investigations of Hale and Clermont (32) and Wu and Wilson (95) have shown that earlywood has significantly higher lignin content than latewood. Lignin may be considered an amorphous block co-polymer which has relatively low affinity for water (14). This indicates that the lignin co-polymer interior is only a partially accessible gel structure. Goring (28), in determining thermal softening of wood components, showed that lignin has a regular and significantly decreasing softening temperature with increased absorbed water content. During regular pulping procedures, lignin is subjected to this transition at 90 to 100°C. This suggests that delignification is a homogeneous reaction. - 39 -As mentioned, earlywood lignin content is significantly higher than that of latewood. Owing to a considerably thinner layer in earlywood, i t might be assumed that the amount of latewood secondary wall lignin differs from that in earlywood. In addition, lignin is thought to be structurally different in various cell wall layers. Wardrop and Bland (90) showed that lignin isolated from the secondary wall is porous, whereas lignin obtained from the compound middle lamella is membranous and dense. Recently this was further confirmed in electron microscopy studies by Cote, Timell and Zabel (19). Topochemical study of sulphate and sulphite processes by Procter, Yean and Goring (69) has suggested also that the macro-molecular size of proto-lignin in the middle lamella is greater than that in the secondary wall. Therefore, the assumption can be made that earlywood proto-lignin should be greater in macro-molecular size than that of latewood. Delignification rate must relate to relative proto-lignin macro-molecular size i f constant monomeric structure and bonding are accepted. Elton (23) indicated that sulphonation and hydrolysis are factors con-trolling delignification rate. Low macro-molecular proto-lignin is immediately soluble after sulphonation, whereas high macro-molecular proto-lignin requires hydrolysis to break sulphonated lignin to soluble sizes. Since the latewood secondary wall is rich in lignin of low macro-molecular size, i t maybe more readily solubilized than that in earlywood. On the other hand, molecular weights of lignin fractions recovered in liquors increase as time is extended for both sulphite and sulphate cooking (97). This is used to reason that during in i t ia l cooking stages the delig-nification mostly takes place in the secondary wall which is rich in low - 40 -molecular weight lignin. This phenomenon may explain results of Table 15 to 22 which show that pulp residual lignin contents for high-yield levels decreased considerably from earlywood to the transition zone and then remained constant or increased only slightly to the end of the growth season. This agrees with Elton's findings (23) in that neutral sulphite pulping of loblolly pine gave the highest residual lignin in earlywood at high-yield cooking. In addition, diffusion of high macro-molecular weight lignin fractions from the middle lamella to cell lumen may be retarded due to limited pore sizes in the secondary wall. But as delignification progresses these pore diameters increase (81), which allows diffusion of larger particles thereafter. This-stage of cooking takes place at about the 70% pulp yield level or when 40 to 50%, of the lignin has been removed. When cooking is further extended, the higher molecular weight lignin becomes soluble. The result is that earlywood lignin is removed and low yield pulp residual lignins are almost equal for earlywood and latewood. Again, this is confirmed by data as shown in Tables 15 to 22, in that earlywood residual lignins are markedly higher than those of latewood at high yield levels. Further cooking considerably increases earlywood delignification. Residual lignin contents become almost constant across the whole increment as low pulp yield levels are approached. 3. Effect of carbohydrate degradation on pulp yields The distribution of wood carbohydrates within mature wood growth increments was studied by Wilson (93) by separating and resolving holo-celluloses. Results with Douglas f ir showed peak chlorite holocellulose (77 to 78%, corrected for lignin) at the point of latewood initiation, - 41 -whereas the lower values (72.5 to 73.57,) were found at the first and last formed parts of growth rings. The constituents of hemicellulose were further analyzed. The results showed glucan plus mannan (88 to 907.) with similar profile to that of holocellulose. Galactan (2.5 to 6.07,) increased from earlywood to latewood, whereas xylan (8.0 to 4.57>) and araban (0.6 to 0.2) decreased from earlywood to latewood. Squire (76) estimated alpha-cellulose patterns within various coniferous wood growth zones. Latewood was significantly higher (2 to 37,) than earlywood. The variation from earlywood to latewood depended on the character of the transition zone. Sigmoidal and flattened patterns were obtained respectively from woods having abrupt and gradual transition zones. Results of investigations on various woods studied for variation of carbohydrate from earlywood to latewood are shown in Table 1. The marked variations of carbohydrate components within growth increments may be caused by uneven distribution of carbohydrate within different tissues of different cell wall layers. Meier (62,63) stated that owing to the glucomannan-rich S£ layer and glucuronoarabinoxylan-rich layer and to a thicker S^  layer in latewood tracheids of Scots pine, the latewood always has a higher glucomannan and a lower glucuronoarabinoxylan content than earlywood. A mature wood cell wall consists of an intricate and highly organized threadlike microfibrillar structure which is combined as crystalline and amorphous regions. The hemicellulose and lignin are thought to surround these microfibrils in an amorphous way (25). - 4 2 -In this study, cooking liquors were heated to 1 7 0 ° C and 1 4 0 ° C for sulphate and Na-base bisulphite cooking, respectively. The thermal softening point varies for different wood components ( 3 0 ) . At 5 0 to 6 0 ° C hemicellulose begins to soften, followed by the wet lignin transition at about 9 0 to 1 0 0 ° C , while cellulose degrades above 2 0 0 ° C . So at regular pulping temperatures, wood hemicelluloses and lignin form a softened gel-like matrix about the rigid cellulose superstructure. It has been shown that in the first stage of sulphate cooking ( 9 4 7 , yield) , wood substance losses are mainly due to hemicellulose dissolution before delignification occurs ( 6 8 ) . Aurell and Hartler ( 6 ) studied pine wood sulphate pulping and confirmed that at 8 0 to 8 5 7 , yield wood components other than lignin were lost, while at about 757o yield lignin was the main component removed, and when approaching the yield range of 6 5 to 457>, there was rather selective lignin removal. Similar results were also obtained from sulphate and sulphite cooking of black spruce by Kalisch and Beazley ( 4 4 ) . During pulping, the removal of carbohydrate obviously depends on process used. Araban is almost completely hydrolyzed and dissolved at a very early stage of sulphite cooking, whereas in the sulphate cook araban is gradually and more uniformly degraded. Xylan and glucomannan are dissolved later in sulphite and sulphate processes ( 2 4 , 4 4 ) . Xylan shows only a small decrease accompanying lower yields in sulphate cooking, whereas in sulphite pulping xylan gradually disappears down to the yield level of about 707o . It then remains constant to about the 5 2 7 , yield level and finally falls rapidly as the 4 0 7 , level is approached ( 4 4 ) . Glucommannan is more resistant to sulphite hydrolysis than xylan, Ahlm and Leopold ( 1 ) studied chemical components of loblolly pine in sulphate pulping from 9 0 to 4 5 7 , yield levels and found that glucomannan was more susceptible to - 43 -removal than lignin and xylan down to the 75%, yield level, but resisted degradation with further cooking. In contrast, the xylan degradation rate was slower and showed some similarity to delignification. Cellulose was lightly attacked until the pulp yield decreased below 50% for both sulphite and sulphate pulping. Chemical variations within increments and how they interact with polysaccharide behaviour in pulp processing have not been much studied. In considering the degradation of loblolly pine chemical components within growth zones during sulphate cooking, Ahlm and Leopold (1) stated that the degradation rates of various wood components were not significantly different between earlywood and latewood. In contrast, from exhaustive extraction of loblolly pine earlywood and latewood by alkaline reagents, Leopold (58) pointed out that xylan-based polysaccharides (arabinoglucuronoxylan) were almost quantitatively removed, bu that latewood showed a slightly higher resistance. As for glucomannan there appeared to be significantly different resistance during alkaline extraction, since 44%, in the late-wood was resistant, whereas for earlywood only about 17% was retained. This was explained as morphological differences between growth zone cell wall structures. Microfibrillar structure plays an important role in pulping, with the amorphous region being more susceptible to attack by cooking liquor than crystalline regions. Variation of crystallinity between earlywood and latewood of western hemlock was studied by Lee (55) using X-ray diffraction. He found that latewood pulp and holocellulose had significantly higher crystallinity than comparable earlywood materials. Native cellulose of high alpha-cellulose content always has high crystall-inity (18). This is coincident with latewood giving higher crystallinity due to its significantly higher alphacellulose. - 44 -Results of the present study show that carbohydrate yields within increments correlate significantly or highly significantly with relative position within increments, except for the black spruce sapwood Increment No.47 pulped to intermediate yield level in Na-base bisulphite, i . e . , 240 min max (Tables 27 and 28.). Carbohydrate yields within increments depend on pulp yields and pulping process rather than species variation. For sulphate cooking to high-yield levels, i .e . , 3 and 12 min max for black spruce and Douglas f i r , carbohydrate yield patterns were the same as those reported earlier for holocellulose (41), except for slightly lower pulp carbohydrate yield in the latewood zone. This might be due to different wood source or to hemicellulose being more susceptible to removal in in i t ia l cooking stages of latewood than earlywood. Carbohydrate yield profiles changed, however, depending on yield level. For 32 min max sulphate cooking of black spruce and Douglas f ir the earlywood carbohydrate yield was lower than with latewood (Fig.l) . This may have resulted from the latewood carbohydrate being more resistant to degradation, possibly due to higher alpha-cellulose, as well as crystallinity in the latewood zone. Na-base bisulphite cooks at high yield levels, i .e . , 43 and 53 min max, for black spruce and Douglas fir showed that latewood carbohydrates were obviously more susceptible to removal than those in the earlywood. With further cooking to intermediate yield level, i . e . , 240 min max cooking, the latewood carbohydrate degradation rate appeared to be considerably less than that of earlywood. - 4 5 -In Na-base bisulphite pulping, however, pulp carbohydrate as well as pulp yields within increments had maximum values in the early-wood at about 2 0 to 3 0 7 , relative position for 4 3 and 5 3 min max cooking times. Further cooking to 2 4 0 min max shifted the yield maximum to the 4 0 to 507o relative position for a l l increments. examined (Fig.2) . 4 . Process and raw pulp yield profiles within increments at various yield levels. From the previous discussions, variations in both morphological structure and chemical composition within increments are shown to affect pulp yields. However, from comparisons of Fig. 1 and 2 , i t can be seen that pulping process also interacts to adjust yield profiles within the growth zone. Sulphate liquor penetration and diffusion are much faster than with sulphite liquor. Therefore, morphological variations within increments affect pulp or carbohydrate yields less in sulphate cooking. The results at pulp yield levels from 3 and 1 2 min max in sulphate cooking of black spruce and Douglas f ir show that delignification rate was not much different from earlywood to latewood, and that pulp carbo-hydrate yields f it a parabola with maximum value at the transition zone. At this yield level, latewood seems to be more susceptible to carbohydrate removal. With further cooking the earlywood is subjected to so-called "chunk" delignification which removes considerable earlywood lignin. At low yield levels, i . e . , 3 2 min max cooking time, pulp and carbohydrate yields increase conspicuously from earlywood to latewood (Fig.l) . This is explained by the fact that at low yield levels carbohydrates are - 46 -seriously exposed to chemical attack due to removal of most of the lignin. Latewood microfibrils are less accessible and more hemicellulose is retained during cooking, as has been discussed previously. In this study, the low yield levels from earlywood to latewood obtained with 32 min max time in sulphate cooking of black spruce and Douglas fir agree with data from various investigations at commercial yield levels in that latewood sulphate pulp yields are higher than those of earlywood (Table 2). It is interesting to note that profile maxima for the three different pulp yields within heartwood increments of the two woods examined change from the in i t ia l transition zone (3 min max) to transition zone (12 min max), then to in i t ia l latewood (32 min max). In addition, these patterns at low yield level suggest relationship with alpha-cellulose intra-incremental profiles established by Squire (76). As for Na-base bisulphite pulping, pulp and carbohydrate yield levels are considerably higher in earlywood than in latewood for high yield cooks (Fig.2) This may be due to the fact that latewood hemicellulose is more susceptible to attack by cooking liquor before delignification begins. Thereby, the 43 and 53 min max cooking levels for black spruce and Douglas fir earlywoods gave much higher pulp and carbohydrate yields than latewood. In addition, a higher content of low-molecular-weight proto-lignin in latewood secondary walls would be removed faster than earlywood proto-lignin which is more highly densified. Further cooking of earlywood considerably decreased pulp and carbohydrate yields, i . e . , at 240 min max, for both black spruce and Douglas f i r . This stage is mainly for "chunk" delignification in earlywood and is accompanied by large losses of carbohydrate. Also at this stage of cooking, xylan-enriched earlywood - 47 -as well as glucomannan-enriched latewood is more resistant, and pulp yields are only slightly different from earlywood to latewood. This agrees with Table 2 data from Hagglund and Johnson (30) for Norway spruce, and de Montigny and Maass (20) data on southern pine Ca-base sulphite cooks, where earlywood yields were either slightly or obviously higher than those from latewood. Further cooking to less than 457<> yield level was not done in this study, but data from Yean and Goring (98) for Na-base sulphite pulping of western hemlock showed that latewood gave higher pulp yield (Table 2). This may relate to higher crystallinity of cellulose and greater resistance of hemicelluloses in the latewood zone. B• Variation Between Wood Zones As mentioned previously, Cross and Bevan cellulose and alpha-cellulose are higher in sapwood than in heartwood (32,46,87,101). Further, Larson (54) analyzed micro-lignin contents and the five principal wood sugars across wood zones of red pine (Pinus resinosa Ai t . ) . His results show definitely chemical differences between earlywood and latewood, as well as age-relationships for both types of tissue. Glucose and mannose yields increased rapidly with age in corewood (15 to 20 yr), then increased gradually from heartwood to stem peripheries, whereas galactose, xylose, arabinose and lignin decreased considerably in corewood and gradually declined from the mature heartwood to stem peripheries. In general, extractives are considerably higher in coniferous heartwood than sapwood (79). Sapwood always contains sugars, fats, starch and soluble constituents; heartwood, on the other hand, has deposits of phenolic materials. For Douglas f ir and western larch (Larix occidentalis Nutt.), Gardner and Barton (27) showed the trend of extractive distribution - 48 -as increasing in a stepwise manner from pith to outer heartwood, then decreasing sharply at the heartwood-sapwood boundary. The result is coincident with polyphenol content across wood zones (38). Similar results are given by Campbell e_t JLL (11) , who examined alcohol-benzene extractives in seasoned Douglas fir sapwood and heartwood, and showed content in the latter to be higher than in the former. A maximum was found at the pith, as well as at the outer heartwood. From the same species Squire et. al_ (77) found a pattern for dihydroquercetin which had a maximum content at heartwood-sapwood boundary and decreased toward stem peripheries and pith. The transition between sapwood and heartwood is accompanied by formation of extractive materials in the xylen and usually a change in color of tissues in Douglas f i r , whereas black spruce heartwood color is not appreciably changed, suggesting possibly less extractive formation. In addition, many heartwood tracheid bordered pits are aspirated, encrusted and occluded during heartwood formation which affects the penetration of cooking liquors. Considering the variation of lignin content between wood zones, Ritter and Fleck (72,73) claimed that sapwood usually was higher in lignin content than heartwood. This agrees with results of this experiment in that sapwood increments have slightly higher lignin contents based on extractive-free water-free wood for both species (Table 3). Sulphite cooking of Douglas f ir heartwood having high extractive content is accompanied by condensation of lignin and poor penetration due - 4 9 -to aspirated pits, so that raw, unscreened pulp yields may be higher in heartwood than sapwood. For black spruce, raw pulp yields from heart-wood and sapwood are similar due to less lignin condensation. In sulphate cooking there are no lignin condensation or penetration barriers. The raw pulp yield largely depends on wood cellulose and hemicellulose content. In this study extractive-free thin wood sections were used for Na-base bisulphite cooking. There would be no lignin condensation, and penetration difficulties would be reduced. This agrees with Douglas fir wood zone variation where heartwood gave slightly higher raw pulp yields, pulp residual lignins and carbohydrate yields. In contrast, black spruce sapwood gave higher raw pulp and carbohydrate yields, but less residual lignin. As for sulphate pulping, Douglas f ir heartwood gave higher raw pulp yields, residual lignin contents and carbohydrate yields, whereas with black spruce these values were only slightly different. C. Variation Between Species The different pulp yields between species mostly depend on variation in wood components, particularly lignin and extractive contents. As mentioned, the sulphite process is very sensitive to species. Douglas fir heartwood contains polyphenol extractives which condense with lignin and/or reduce bisulphite ions with formation of thiosulphate. This species also contains an abundance of resin which causes penetration difficulties so that the delignification is retarded. Black spruce is thought to be unaffected in these ways. The sulphate process is unaffected by wood species, having l i t t l e retardation of penetration and lignin condensation. - 50 -Variation of lignin contents of various species is shown in Table 1. For this study, as shown in Table 13 the average heartwood and sapwood increment lignin contents (based on extractive-free water-free wood) were 23.41% (20.81 to 26.57%) and 25.14% (21.70 to 30.45%) for black spruce and Douglas f i r , respectively. By using extractive-free thin wood sections the pulp yield variations between species were restricted to differences in cell wall chemical components. In general, sulphate cooks of this study showed that between species variation of raw pulp yield and residual lignin of Douglas fir were slightly higher than for black spruce, but without statistical differences, except that carbohydrate yields of Douglas f ir were significantly higher than for black spruce. For Na-base bisulphite pulping, Douglas fir raw pulp and carbohydrate yields were significantly higher than for black spruce, and Douglas fir pulp residual lignin was also higher than black spruce, but not significantly different. - 51 -CONCLUSIONS The following conclusions may be drawn in regard to sulphate and Na-base bisulphite intra-incremental raw pulps from black spruce and Douglas f ir: (1) Raw pulp and pulp carbohydrate yields were correlated with relative positions within growth increments. Profiles varied at different yield levels and with pulping process. (2) Raw pulp and pulp carbohydrate yields appeared to be affected by variation in wood anatomical and wood chemical components within growth increments. No profiles were simply correlated with wood specific gravity. (3) Pulping process considerably affected raw pulp and pulp carbohydrate yield profiles within growth increments. For 3 and 12 min max sulphate cooking, both black spruce and Douglas fir displayed a parabolic function with maxima in the transition zone. With further sulphate cooking to 32 min max these maxima shifted further toward the latewood, i .e . , 70 to 80% relative incremental position. In contrast, Na-base bisulphite raw pulp at high yield levels, i . e . , 43 and 53 min max cooking time, gave maximum pulp and pulp carbohydrate yields in earlywood, i . e . , 20 to 30%, relative incremental position. Yields decreased sharply in the transition zone and remained constant in the latewood portion. Further cooking to 240 min max changed position of maximum values to the transition zone, i . e . , 40% relative position. (4) Delignification rate differed within increments for the pulping processes. In the in i t ia l cooking stage, latewood lignin seemed - 52 -to be more easily removed than that from earlywood. At high yield levels, such as 3 min max sulphate and 43 or 53 min max in Na-base bisulphite processing, the pulp residual lignin contents based on water-free pulp followed similar patterns, in that maxima were found in earlywood at about the 20% relative position, abruptly decreased in the transition zone and then slightly increased in the latewood. With further cooking, considerably more earlywood lignin was removed, whereas latewood lignin decreased more slowly. At low yield levels, i . e . , 32 min max sulphate, the residual lignin patterns varied slightly, or remained constant throughout the whole increment. Raw pulp yields, residual lignin contents and pulp carbohydrate yields (based on extractive-free water-free wood) were not sig-nificantly different for combined data of heartwood and sapwood, both woods and two pulping processes, except for Na-base bisulphite pulp carbohydrate yields which showed significantly higher values for sapwood. Sulphate raw pulp yields and residual lignin contents obtained by combining data from a l l cooking levels and wood zones were not significantly different between the two species examined, except for Douglas fir carbohydrate yield which was significantly higher than that of black spruce. For Na-base bisulphite pulping, Douglas fir raw pulp yields and pulp carbohydrate yields were highly significantly greater than those from black spruce, whereas pulp residual lignin was non-significantly different. - 53 -REFERENCES 1. Ahlm, C.E. and B. Leopold. 1963. Chemical composition and physical properties of wood fibers. IV. Changes in chemical composition of loblolly pine fibres during kraft cook. Tappi 46 : 102-107. 2. Annergren, G.E. and S.A. Rydholm. 1959. On the behaviour of the hemicellulose during sulphite pulping. Svensk Papperstid. 62 : 737-746. 3. . 1960. On the stabilization of glucomannan in the pulping processes. Svensk Papperstid. 63 : 591-600. 4. Aurell, R. 1963. The effect of lowered pH at the end of birch kraft cooks. Svensk Papperstid. 66: 437-442. 5. . 1964. Kraft pulping of birch. Part I. The changes in the composition of the wood residue during the cooking process. Part 2. The influence of the charge of alkali on the yield, carbohydrate composition and properties of the pulp. Svensk Papperstid. 67 : 43-49 ; 89-95. . and N. Hartler. 1963. Sulfate cooking with the addition of reducing agents. Part III. The effect of added sodium borohydride, Tappi 46 : 209-214. . 1965. Kraft pulping of pine. Part 1. The changes in the composition of the wood residue during the cooking process. Part 2. The influence of the charge of alkali on the yield composition and properties of the pulp. Svensk Papperstid. 68 : 59-68 ; 97-102. 8. Bailey, A .J . 1936. Lignin in Douglas f i r . Composition of the middle lamella. Ind. Eng. Chem.(Anal. Ed.). 8 : 52-55. - 54 -9. Berzins, V. 1966. Micro kappa numbers. Pulp Paper Mag. Can. 67 : T206-T208. 10. Bisset, I.J.W. and H.E. Dadswell. 1950. The variation in cell length within one growth ring of certain angiosperms and gymnosperms. Austral. Forestry. 14 : 17-29. 11. Campbell, J .R. , Swan, E.P. and J.W. Wilson. 1965. Comparison of wood and growth zone extractives in Douglas f ir . Pulp paper Mag. Can. 66 : T248-T252. 12. Chidester, G.H., Bray, M.W. and C.E. Curran. 1940. Growth factors influencing the value of Jack pine for kraft and sulphite pulp. Paper Trade J . 109(13) : 36-42. 13. Chiu, S.T. 1967. Relationship of wood specific gravity to tangential area shrinkage of microspecimens. Unpub. Report, Fac. For., Univ. Brit. Col . , Vancouver, B.C. 14. Christensen, G.N. and K.E. Kelsey. 1959. The sorption of water vapor by the constituents of wood. Holz Roh - Werkstoff 17 : 189-203. 15. Christiansen, C.B., Hart, J.S. and J.H. Ross. 1957. Sulphidity as a variable in the pulping of western red cedar; The effect of the Na2S/wood ratio on pulp properties. Tappi 40 ; 355-361. 16. Cole, D.E. , Zobel, B.J. and J.H. Roberds. 1966. Slash, loblolly, and longleaf pine in a mixed natural stand; a comparison of their wood properties, pulp yields, and paper properties. Tappi 49 ; 161-166. 17. Colombo, P. , Corbetta, D., Pirotta, A. and G. Ruffini. 1964. The influence of thickness of chips on pulp properties in kraft cooking. Svensk Papperstid. 67 : 505-511. - 55 -18. Conrad, C C . and A.G. Scroggie. 1954. Chemical characterization of rayon yarns and cellulose raw materials. Ind. Eng. Chem. 37 : 592-598. 19. Cote, W.A., Timell, T.E. and R.A. Zabel. 1966. Studies on com-pression wood. Part I. Distribution of lignin in compres-sion wood of red spruce (Picea rubens Sarg.). Holz Roh-Werkstoff 24 : 432-438. 20. de Montigny R. and 0. Maass. 1935. Investigation of physical chemical factors which influence sulphite cooking. Dept. Interior Forest Service Bull. No.87., Canada. 21. Dinwoodie, J.M. 1963. Variation in tracheid length in Picea sitchensis. Special Report No.16, Forest Prod. Res., London. 55 pp. 22. Dorland, R.M., Leask, R.A. and J.W. McKinney. 1956. The effect of sulphite acid strength on pulp properties for slush and high-yield cooking. Pulp Paper Mag. Can. 57 : 122-126. 23. Elton, E.F. 1963. Rate phenomena in the neutral sulphite deligni-fication of loblolly pine (Pinus taeda L . ) . Tappi 46 : 404-409. 24. Eriksson E. and 0. Samuelson. 1963. Isolation of hemicellulose from sulphite cooking liquors. Part 2. Bisulfite cooking. Svensk Papperstid. 66 : 407-411. 25. Frey-Wyssling, A. 1957. The general structure of fibres. In Trans-actions of the Symposium on Fundamental of Papermaking Fibres, held at Cambridge, 23-27 Sept. 1957, organized by the British Paper and Board Association, P. 1-6, London. 26. . and K. Mitrakos. 1959. Deposition of submicroscopic metal particles in plant fibres. J . Ultrastructure Research 3 : 228-233. - 56 -27. Gardner, J .A.F. and G.M. Barton. 1960. The distribution of dihydroquercetin in Douglas f ir and western larch. Forest Prod. J . 10 : 171-173. 28. Goring, D.A.I. 1963. Thermal softening of lignin, hemicellulose and cellulose. Pulp Paper Mag. Can. 64 : T517-T527. 29. Gustafsson, C. , Sundman, J . , Pettersson, S. and T. Lindh. 1951. The carbohydrates in some species of wood. Paperi ja Puu 33 : 300-301. 30. Hagglund, E. and T. Johnson. 1927. Chemical properties and different value of early and latewood as raw material for sulphite pulp production. Zellstoff u. Papier 7 : 49-50. Transl. No.29, Fac. For., Univ. B.C. , Vancouver, B.C. 31. . and H. Nihlen. 1934. The significance of high calcium cooking acid in the sulphite process. Svensk Papperstid. 37 : 754-756. 32. Hale, J.D. and L.P. Clermont. 1963. Influence of prosenchyma cell-wall morphology on basic physical and chemical characteristics of wood. J . Polymer Sc. C(2) : 253-261. 33. Hart, J.S. and R.K. Strapp. 1951. Sulphite studies - The influence of cooking variables. Part 1. Influence of combined SO ,^ free SO2 a n c * digester pressure. Part II. Influences of digester pressures and temperature. Pulp Paper Mag. Can. 52 : T148-T154. 34. Hartler, N. 1963. The effect of wood compression on acid bisulphite pulps from springwood and sumraerwood. Svensk Papperstid. 66 : 526-531. - 57 -35. Hartler, N. and W. Onisko. 1962. The interdependence of chip thickness, cooking temperature and screenings in kraft cooking of pine. Svensk Papperstid. 65 : 905-910. 36. Hata, K. 1950. Pulp of Pinus densiflora wood. Chemical composition of the spring - and summerwoods. J . Japan. For. Soc. 33 : 257-260. Transl. No.33, Fac. For., Univ. Brit. Col . , Vancouver, B.C. 37. H i l l i s , W.E. 1962. The distribution and formation of polyphenols within the tree. In Wood Extractives, edited by W.E. H i l l i s . Academic Press, N.Y. 513pp. 38. Homoky, S. 1965. Intra-increment relationship of microcompression. Unpub. Report, Fac. For., Univ. Brit. Col . , Vancouver, B.C. 39. .1966. Relationship of some coniferous wood strength properties to specific gravity variations within growth increments. Unpub. Thesis, Fac. For., Univ. Brit. Col . , Vancouver, B.C. 40. Howard, E . J . 1951 Sulphur reactions in sulphite cooking. Part II. Some physio-chemical aspects. Pulp Paper Mag. Can. 52 : 91-97. 41. Ifju, G., Wellwood, R.W. and J.W. Wilson. 1965. Relationship between certain intra-increment physical measurements in Douglas f i r . Pulp Paper Mag. Can. 66 : T475-T483. 42. Johnson, D.B., Moore, W.E. and L.C. Zank. 1961. The spectrophotometrie determination of lignin in small wood samples. Tappi 44 : 793-798. 43. Jones, E.D. , Campbell, R.T. and G.G. Nelson. 1966. Springwood-summerwood separation of southern pine pulp to improve paper qualities. Tappi 49 : 410-414. - 58 -44. Kalisch, J.H. and W. Beazley. 1960. Sulphite and kraft pulping studies with a new digester sampler. Pulp Paper Mag. Can. 60 : T452-T464. 45. Kennedy, R.W. 1966. Intra-increment variation and heritability of specific gravity, parallel-to-grain tensile strength, stiffness, and tracheid length in clonal Norway spruce. Tappi 49 : 292-296. 46. Kennedy, R.W. and J.M. Jaworsky. 1960. Variation in cellulose content of Douglas f i r . Tappi 43:- 25-27. 47. Klem G.G. 1950. Specific gravity of spruce wood, its variation in wood structure and pulp degree of delignification, and the effect of these factors on yield and sulphite pulp quality. Norske Skogforsksvesen 10 : 367-396. 48. Kulkarni, G.R. and W.J. Nolan. 1955. The mechanism of alkaline pulping. Paper Ind. 37 : 142-151. 49. Lange, P.W. 1947. Some views on the lignin in the woody fiber during the sulfite cook. Svensk Papperstid. 50 : 130-134. 50. . 1954. Mass distribution in the cell walls of Swedish spruce and birch. Svensk Papperstid. 57 : 533-537. 51. . and A. Kjaer. 1957. Quantitative chemical analysis of different portions of the cell wall in wood and pulp fibres, using interference microscopy. Norsk Skogind. 11 : 425-432. 52. • and E. Lindvall. 1954. Adsorption and diffusion of substantive dyes in cellulose fibres. Svensk Papperstid. 57 : 235-241. 53. Laroque, G.L. and 0. Maass. 1941. The mechanism of the alkaline delig-nif ication of wood. Can. J . Research 19(B) : 1-16. - 59 -54. Larson, R.R. 1966. Changes in chemical composition of wood cell walls associated with age. Forest Prod. J . 16 : 37-45. 55. Lee, C.L. 1961. Crystallinity of wood cellulose fibers. Forest Prod. J . 11 : 108-112. 56. Legg, G.W. and J.S. Hart. 1960. Alkaline pulping of Jack pine and Douglas f i r . The influence of sulphide and effective alkali charge on pulping rate and pulp properties. Pulp Paper Mag. Can. 61 : T299-T304. 57. Legg, G.W. and J.S. Hart. 1960. Alkaline pulping of poplar and birch. The influence of sulfidity and effective alkali on the rate of pulping and pulp properties. Tappi 43 : 471-484. 58. Leopold, B. 1961. Chemical composition and physical properties of wood fibres. I. Preparation of holocellulose fibers from loblolly pinewood. Tappi 44 : 230-232. 59. Mabuni, C.T. and A.M. Unrau. 1961. The chemical composition and some physical properties of Hawaiian forest woods. Tappi 44 : 227-229. 60. Mcintosh, D.C. 1963. Tensile and bonding strengths of loblolly pine kraft fibers cooked to different yields. Tappi 46 : 273-277. 61. Marton, J . 1967. Determination of lignin in small pulp and paper samples using the acetyl-bromide method. Tappi 50 : 335-337. 62. Meier, H. 1959. The distribution of hemicellulose components in pine fibres. Svensk Paperstid. -62 : 687-691. 63. . 1964. General chemistry of cell walls and distribution.of the chemical constituents across the wall. In The Formation of Wood in Forest Trees, edited by M.H. Zimmermann, Academic Press, N.Y. 562pp. - 60 -64. McGovern, J.N. and G.H. Chidester. 1938. Sulphite pulps from the top, middle and butt logs of western hemlock of four growth types. Paper Trade J . 106(23) : 37-39. 65. Mork, E. 1928. Die Qualitat des Fichtenholzes unter besondeser Rlicksichtnahme auf Schleif - und Papierholz. Papier Fabrikant 26 : 741-747. 66. Nylinder, P. and E. Hagglund. 1954. Effect of site and tree properties on yield and quality of Norway spruce sulphite pulp. Medd. Statens Skogsforshningsinst 44 : 1-184. 67. Overbeck, W. and H.F. Mliller. 1942. The hydrolysis of different wood species with water under pressure and the resulting changes of the wood constituents, the lignin in particular. Svensk Papperstid. 45 : 357-360. 68. Polcin, J . , Farkas, J . and M. Karhanek. 1967. Morphological structure changes of cellulose fibres during sulphate delignification investigated by electron microscope. Pulp Paper Mag. Can. 68 : T573-580. 69. Procter, A.R., Yean, W.Q. and D.A.I. Goring. 1967. The topochemistry of delignification in kraft and sulphite pulping of spruce wood. Pulp Paper Mag. Can. 68 : T445-T453. 70. Reid, H.A. 1962. Some factors affecting the kraft pulping of pine woods. J . APPITA 15 : 102-110. 71. Regnfors, L. and L. Stockman. 1956. Effect of chemical/wood ratio on the kraft cooking. Svensk Papperstid. 59 : 509-520. 72. Ritter, G.J. and L . L . Fleck. 1923. Chemistry of wood VI. Results of analysis of heartwood and sapwood of some American woods. Ind. Eng. Chem. 15 : 1055-1056. - 61 -73. Ritter, G.J. and L.L . Fleck. 1926. Chemistry of wood VIII. Further studies of sapwood and heartwood. Ind. Eng. Chem. 18 : 576-577. 74. . 1926. Chemistry of wood IX. Spring wood and summer wood. Ind. Eng. Chem. 18 : 608-609. 75. Rydholm, S.A. 1965. Pulping Processes. Interscience Pub., N.Y. 1269pp. 76. Squire, G.B. 1967. Examination of cellulose-lignin relationships within coniferous growth zones. Unpb. Thesis, Fac. For., Univ. Brit. Col. , Vancouver, B.C. 77. .Swan, E.P. and J.W. Wilson. 1967. New micro-technique for determination of wood extractives. Pulp Paper Mag. Can. 68 : T431-T437. 78. Stamm, A .J . 1953. Diffusion and penetration mechanism of liquids into wood. Pulp Paper Mag. Can. 54 : T54-T63. 79. .and H.T. Sanders. 1966. Specific gravity of the wood substance of loblolly pine as affected by chemical composition. Tappi 49 : 397-400. 80. Steel, R.G.D. and J.H. Torrie. 1960. Principles and Procedures of Statistics. McGraw-Hill Book Co., N.Y. 481pp. 81. Stone, J . E . and A.M. Scallan. 1965. A study of cell wall structure by nitrogen adsorption. Pulp Paper Mag. Can. 66 : T407-T414. 82. Strapp, R.K., Kerr, W.F. and K.E. Vroom. 1957. Comparison of bases used in sulphite pulping - - Part 1. Pulp Paper Mag. Can. 58 : T277-T284. - 62 -83. Van Buijtenen, J . P . , Zobel, B.J. and P.N. Joranson. 1961. Variation of some wood and pulp properties in an even-aged loblolly pine stand. Tappi 44 : 141-144. 84. Vroom, K.E. 1957. The "H" factor: A means of expressing cooking times and temperatures as a single variable. Pulp Paper Mag. Can. 58 : 155-159. 85. Walchi, V.O. 1947. Die Einlagerung von Kongorot in Zellulose. Holzforsch. 1 : 20-32. 86. Watson, A . J . and H.E. Dadswell. 1962. Influence of fibre morphology on paper properties. Part II. Earlywood and latewood. J . APPITA 15 :116-128. 87. Wardrop, A.B. 1951. Cell wall organization and properties of the xylem. I. Cell wall organization and the variation of breaking load in tension of the xylem conifer stems. Austral. J . Sci. Res. B4 391-414. 88. 1962. Fundamental studies in wood and fibre structure relating to pulping processes. J . APPITA 16 : XV-XXX. 89. . 1963. Morphological factors involved in the pulping and beating of wood fibres. Svensk Papperstid. 66 : 231-247. 90. . and D.E. Bland. 1959. The process of lignification of woody plants. In Proceedings of the Fourth International Congress of Biochemistry (Vienna); Biochemistry of Wood, edited by K. Kratzl and G. Bi l l ick. Pergamon Press, N.Y. 285pp. 91. .and G.W. Davies. 1961. Morphological factors relating to the penetration of liquids into wood. Holzforsch. 15 : 129-141 - 63 -92. Wilcox, H. 1962. Cambial growth characteristics. In Tree Growth, edited by T.T. Koxlowski. Ronald Press Co., N.Y. 442pp. 93. Wilson, J.W. 1964. Wood Characteristics III. Intra-increment physical and chemical properties. Res. Note No.45. Pulp Paper Res. Inst. Can.. 94. Wood Tech. Procedures. 1962. Lignin in wood (Klason). AM/L-1/62. Fac. For., Univ. Brit. Col . , Vancouver, B.C. 95. Wu, Y.T. 1964. Intra-increment lignin content of five western Canadian coniferous woods. M.F. Thesis, Fac. For., Univ. Brit. Col . , Vancouver, B.C. 96. . and J.W. Wilson. 1967. Lignification within coniferous growth zones. Pulp Paper Mag. Can. 68 : T159-T164. 97. Yean, W.Q. and D.A.I. Goring. 1964. Simultaneous sulphonation and fractionation of spruce wood by a continuous flow method. Pulp Paper Mag. Can. 65 : T127-T132. 98. . 1965. The molecular weights of lignosulphonates from morphologically different subdivisions of the wood structure. Svensk Papperstid. 68 : 787-790. 99. Yllner, S., Ostberg, K. and L. Stockman. 1957. A study of the removal of the constituents of pine wood in the sulphate process using a continuous liquor flow method. Svensk Papperstid. 60 : 795-802. 100. Zobel, B . J . , Stonecypher, R., Browne, C. and R.C. Kellison. 1966. Variation and inheritance of cellulose in the southern pine. Tappi 49 : 383-387. 101. . and R.L. McElwee. 1958. Variation of cellulose in loblolly pine. Tappi 41 : 167-170. Table 1. Coniferous earlywood (E) and latewood (L) chemical compositions from the literature based on oven-dry wood Growth ^ Hemicellulose Extractives Species Zone H.C. &C-C. Ar. Xy. Gl. Ma. Ga. Lignin H.W. A.B. Ref. Picea abies (Mill.) E 3.0 11.0 64.5 17.0 4.5 29 B.S.P. L 2.0 8.5 62.0 19.5 8.0 Pseudotsuga menziesii E 70.9 67. 4 31.2 4.09 32 (Mirb.) Franco L 75.3 74. 6 28.1 2.85 E 56. occ 32.6 4.67 74 L 59. 4 29.2 3.76 Pinus sylvestris L. E 56. 7C 1.0 18.6 20.3 3.4 63 L 56.2 1.8 14.1 24.8 3.1 E 3.5 10.0 63.5 19.0 4.0 29 L 3.0 9.5 64.5 17.5 5.5 Pinus densiflora L. E 52.37 76. 57 5.77 27.91 3.00 5.79 36 L 55.73 77. 39 6.88 26.74 2.43 3.53 Pinus resinosa Ait. E 73.2 61. 9 27.9 5.67 32 L 74.8 70. 9 24.7 4.66 Pinus taeda L. E 75.2 1.4 6.4 45.9 9.6 1.2 28.3 58 L 71.3 0.7 6.4 46.9 11.0 1.6 27.4 E 69.85 49. 01 31.84 29 L 71.56 53. 36 29.28 E 75.7 60 L 71.7 E 0.8 4.8 47.4 10.4 2.0 30.0 1 L 1.7. 5.3 45.5 12.0 2.4 28.3 G.Z. : Growth zone Ar. : Arabinan Ga. : Galactan H.C. : Holocellulose Xy. : Xyl an H.W. ; Hot water soluble -C. : Alpha-cellulose Gl. : Glucan A.B. : Alcohol-benzene soluble C : Cellulose (non--described) Ma. ; Mannan Table 2. Coniferous earlywood (E) - latewood (L) raw pulp yields-and residual lignins at various cooking times (T) from the Literature and summary of present experimental values based on extractive-free water-free wood. Raw Pulp Yield, % : Residual Li gnin, % Species •T, Literature Experimental Min E L E L •L-•E E L L-•E Ref Sulphate Process Pinus taeda L. 240 46.0 48.1 2 1 1. 1 1.2 0 2 1 240 50.0 58.0 ' 8 0 4 9 a 5;7a 0 8 86 240 45.6 47.1 1 5 60 Pinus radiata D. Don 180 51.0 50.0 -1 0 3 . a 8 4.8a 1 0 86 Picea mariana (Mill.) 3 h 60.76 60.07 , -0 69N S 5 97 5.07 -0 NS 90 B.S.P. 12h 57.41 57.50 0 09N S 4 60 3.83 -0 ?7NS 32h 46.22. 49.04. 2 82 0 99 0.97 -0 02NS 12S .57.35 58.80 1 45N S 4. 00 2.43 -1 5?NS Pseudotsuga menziesii . h 3 67.42 63.45 -3 97N S 7. 91 5.63 -2 28" (Mirb.) Franco 12h 62.40 58.88 -3 5 2NS 3 27 2.81 -0 46N S 32h 47.87 49.87 2 oo N S 0 96 0.73 -0 2 3NS . 12S 57.91 55,79 Sulphite Process -2 12NS 4 54 3.08 X -1 46 Pinus sp. (1) 51.5 44.3 -7 2 3 4 1.6 -1 8 20 Tsuga heterophylla (2) 360 43.0 45.0 2 0 98 (Raf.) Sarg Picea abies (Mill.) (1)1020 51.3 51.0 -0 3 3. 0 3.3 0 3 30 B.S.P. 960 52.5 52.2 -0.3 7. 4 6;9 -0 •5 30 1290 50.0 47.9 -2 1 1. 0 0.8 -0 2 30 •Picea mariana (Mill.) (3) 43h 70.49- 64.17 -6 ** 32 11. 31 10.31 -1 ooN S 53h 68.60 61.61 -6 **/ 99 NS 10 10. 58 7.67 -2 240h 47.19 46.09 -1 3. 21 2.01 -1 * 20 240s 53.67 52.83 -0 84NS 1. 81 1.09 -0 ? 2NS Pseudotsuga menziesii (3) 43h 84.17 77.89 -6 28 12. 79 10.33 -2 46" (Mirb.) Franco 53h 80.80 76.41 -4. ** 39 11. 20 10.03 -1. I ?NS 240h 61.51 59.87 -1. 64NS 4. 80 2.24 -2. A>V 56 240S 60.14 54.92 -5 22N S 4. 39 1.66 -2. 7 3NS a : Lignin % = 0.15 X kappa number h : Heartwood increment s : Sapwood increment (1) : Ca-base sulphite (2) : Na-base sulphite (3) : Na-base bisulphite * : Significant at 0.05 probability level ** : Significant at 0.01 probability level NS : Non-significantly different. Table 3. Description of stems and growth increments used in micro-pulping studies. Stem Characteristics Growth Increment Examined Processing Age, Diameter Growth Sapwood, yr. DBH rate, cm Width Latewood, Specific Lignin gravity 0 % Yield Level and cm. mm/ yr No. mm Pulping Process Picea mariana (Mill.) B.S.P. 52 31.1 2.94 3.0 31Ah 4.17 34.0 0.278-0.693 20. 81-26.57 3,OH~ 3lB h 4.05 34.0 0.278-0.693 20. 81-26.57 3,H + 47S 3.85 32 .,0 0.255-0.743 21. 10-26.19 1,0H~;1,H+ Pseudotsuga menziesii (Mirb.) Franco. 65 39.6 3.05 4.2 30Ah 3.82 38.0 0.214-0.801 21. 70-27.47 3,OH" 30Bh 3.82 38.0 0.214-0.801 21. 70-27.47 3,H + 57 s 4.22 40.0 0.237-0.700 22. 64-30.45 1,0H~;1,H+ A,B : Block No. h,s : Heartwood and sapwood increments respectively a : Yield levels (1 or 3) depending on different cooking time b ; Pulping Processes; sulphate (OH ), Na-base bisulphite (H+) c ; Extractive-free oven-dry weight and green volume d : Extractive-free water-free wood Table 4. Absorptivity of lignins from woods and pulps of black spruce and Douglas f i r . Source Lignin, % Sample Weight mg Absorbance Dilution, Absorptivity, Average Standard at 282 nju. ml cm ''"liter g "*" Absorptivity Deviation. Black spruce 30.12' 28.61* Wood 31.33E 30.75L Douglas f ir 27.70 26.07£ 32.30E 30.43L Black spruce Sulphate 6.84 44.54 44.36 43.92 Wood Pulps 0.481 0.466 0.467 200 200 201 31.58 30.72 31.02 31.11 + 0.44 Na-base bisulphite 4.62 65.00 64.94 65.30 0.380 0.382 0.392 205 200 200 26.00 25.46 25.99 25.82 + 0.31 Douglas f ir Sulphate 6.89 43.94 44.28 43.92 0.463 0.466 0.467 200 200 201 30.59 30.55 31.02 30.72 + 0.26 Na-base bisulphite 4.99 61.30 62.10 61.74 0.400 0.410 0.404 200 200 200 26.15 26.46 26.25 26.29 -0.16 a ; Wood Tech. Procedure, AM/L-1/62(94) b : Residual Lignin % = 0.15 x micro kappa No. (9) E : Earlywood average L : Latewood average Table 5. Species, growth increment numbers, moisture content of wood sections and times at maximum temperature for sulphate and Na-base bisulfite cooks. Pulping process Species Increment No. and Wood Zone Moisture Content,7o Cooking Time, min max Sulphate Black spruce Douglas f ir 31 31h, 47S 31h 30 30h, 57S 30h 18.1 18.1 18.1 17.9 17.9 17.9 3 12 32 3 12 32 Na-base bisulphite Black spruce h s a Douglas fir 31 31h 31h, 47S 31 30h 30h, 57S 18.1 18.1 18.1 17.9 17.9 17.9 Heartwood Sapwood Cooking time, minutes at maximum temperature 43 53 240 43 53 240 0 0 Table 6. Sulphate and Na-base bisulphite cooking variables Sulphate Na-base Bisulphite Cooking liquor (initial) Effective alkali (Na20) 37.4 g/1 Sulphides 13.8 g/1 Sulphidity 31.1% Liquor/wood ratio 60:1 Pulping temperature 170°C max. Cooking liquor (initial) Total S02 6.20% Free S02 4.85% Combined S02 1.35% Liquor/wood ratio 60;1 Pulping temperature 140°C max. Table 7. Analysis of variance on the effect of various thicknesses of black spruce and Douglas fir wood sections on sulphate and Na-base bisulphite pulp yields Source DF SS MS F Treatment 3 4.39 1.46 0.11' Error 28 375.99 13.43 Total 31 380.38 NS : Non-significant Table 8. Analysis of variance on the effect of screen mesh size on black spruce sulphate cooking Source DF SS MS F Treatment 2 23.76 11.88 0.481 Error 15 368.40 24.56 Total 17 392.16 NS : Non-significant Table 9. Analysis of variance on effect of between screen positions on pulp yields Pulping Position in Screen Species Process Growth Zones Increment , % Position, % F Earlywood 11.0 13.9 21 74 0.24 N S Sulphate Transition zone 60.2 63.2 44 85 4.73 N S Latewood 88.0 12 0.66 N S Black 91.2 62 spruce Earlywood 12.0 15.2 79 58 0.02 N S Na-base Transition 48.9 46 4.45 N S bisulphite zone 51.9 18 Latewood 79.2 82.2 27 88 2.65 N S Earlywood 10.0 13.2 72 22 ** 19.28 Sulphate Transition zone 61.7 65.0 58 44 o.oo N S Latewood 87.0 83 0.01 N S Douglas 89.8 64 fir Earlywood 15.9 19.4 61 24 39.62 Na-base Transition IU 9 13.84 bisulphite zone 79 Latewood 87.3 89.7 42 49 0.09 N S ** : Significant at 0.01 probability level NS : Non-significant a : From beginning of earlywood Table 10. Analysis of variance on the effect of within screen position on black spruce and Douglas fir sulphate and Na-base bisulphite pulp yields. Source DF SS MS Within position 0.00 0.00 0.00 NS Species x Within position 0.31 0.31 0.02 NS Pulping Process x Within position 2.93 2.93 0.23' NS ro Error Total 50.38 53.62 12.60 NS Non-significant Table 11. Calculation of replication number from three positions within growth increment for two species and two pulping processes Species Cooking Growth Zones Replication Process No. (N)a Earlywood 1.39 Sulphate Transition zone 0.18 Black spruce Latewood 0.62 Na-base Earlywood 0.56 bisulphite Transition zone 0.20 Latewood 1.00 Earlywood 2.28 Sulphate Transition zone 1.64 Latewood 0.60 Douglas fir Earlywood 1.33 Na-base Transition zone 0.67 bisulphite Latewood 0.92 Average 0.95 *N = t 2 x s 2 /d 2 (80) Table 12. Effect of elapsed time on residual lignin determinations for Douglas fir sulphate pulp and black spruce Na-base bisulphite pulp Elapsed Douglas Fir Sulphate Pulp Black Spruce Bisulphite Pulp Time, hr Calculated Relative Calculated Relative R . L . , ^ Change, % R. L . , % Change, % 1.5 7.70 40.47 22.72 198.43 5.0 11.21 58.96 14.54 126.97 10.0 15.67 82.41 13.33 116.40 19.5 18.44 96.96 . 12.97 113.26 28.5 18.46 97.07 12.64 110.34 46.5 18.89 99.32 12.64 110.34 56.0 18.82 98.99 11.63 101.57 71.0 19.02 100.00 11.45 100.00 96.0 19.34 101.67 11.94 104.27 119.5 19.38 101.92 11.86 103.60 144.0 19.57 102.93 12.58 109.89 168.5 19.55 102.82 11.61 101.35 192.5 19.94 104.85 13.00 113.48 214.5 19.94 104.85 12.56 109.66 267.0 20.15 105.98 12.87 112.36 333.5 20.39 107.22 13.12 114.60 R.L. : Pulp residual lignin based on water-free pulp Table 13. Distribution of wood lignin within increments of black spruce and Douglas fir based on extractive-free water-free weight Black Spruce Increment No. 31 (heartwood) Relative P o s i t i o n , 5 . 6 12.7 20.7 28.7 36.7 45.2 53.9 70.7 85.6 93.3 Lignin, % 24.67 26.57 24.46 26.01 23.95 23.51 22.67 20.87 22.03 20.81 Increment No.47 (sapwood) Relative Position,*% 2.8 11.3 22.5 33.3 38.8 48.2 60.4 73.9 85.6 91.1 Lignin, 1 25.11 26.19 25.57 24.44 23.14 22.97 21.10 21.57 21.34 21.12 Douglas f i r Increment No. 30 (heartwood) Relative P o s i t i o n , 6 . 3 17.0 26.9 36.4 46.3 56.9 63.4 73.7 83.1 94.8 Lignin, % 26.87 27.47 26.48 25.84 23.62 22.72 21.80 21.97 21.70 22.72 Increment No. 57 (sapwood) Relative Position,"% 7.8 12.8 20.7 26.2 34.5 45.8 61.8 70.7 85.2 94.2 Lignin, % 29.48 29.89 30.45 28.95 25.94 24.21 23.81 23.37 22.81 22.64 * : Relative position from beginning of earlywood Table 14. D i s t r i b u t i o n of wood s p e c i f i c gravity within increments of black spruce and Douglas f i r based on ext r a c t i v e - f r e e oven-dry weight Black spruce Increment No. 31 (heartwood) Relative P o s i t i o n . ^ % 7.8 21.2 32.4 49.4 55.2 61.3 70.0 78.5 83.9 88.9 S p e c i f i c gravity 0.278 0.310 0.310 0.361 0.423 0.539 0.642 0.690 0.693 0.665 Increment No. 47 Relative P o s i t i o n , % 8.5 22.5 33.5 51.3 57.2 67.5 73.9 79.9 85.6 91.7 S p e c i f i c g r a v i t y * " 0.255 0.259 0.275 0.317 0.391 0.593 0.653 0.707 0.734 0.693 Douglas f i r Increment No. 30 Relative P o s i t i o n , 8 . 2 23.2 35.4 44.8 51.0 57.3 67.2 73.4 84.7 97.0 S p e c i f i c g r a v i t y * * 0.214 0.230 0.257 0.275 0.326 0.429 0.682 0.739 0.779 0.801 Increment No. 57 Relative P o s i t i o n 'V. 10.3 20.7 31.7 45.8 50.9 58.9 67.6 76.4 91.2 97.1 S p e c i f i c g r a v i t y * * 0.237 0.248 0.275 0.344 0.507 0.653 0.700 0.683 0.639 0.610 * : Relative p o s i t i o n from beginning of earlywood ** : Average of two r e p l i c a t e s Table 15 Sulphat raw pulp residual l i g n i n and carbohydrate yields within Increment No. 31 (heartwood) of black spruce at three cooking times' Cooking Time at Max Min Relative ^ Po s i t i o n , " % Pulp Y i e l d 3 , % • 10 62 4 37 21 59. 2 63 32 61 4 48 43 '61 7 57 52 61. 3 28 58 60 2 68 64 60 2 28-78 60 5 13 86. 60. 6 09 94 59 4 91 3 58 14 59. 34 61 39 61 47 61 44 61 29 . 60 28 60 55 60. 74 59 00 Average,% 60 26 59. 49 61 44 61 52 61. 36 60 99 60 28 60 34 60. 42 59 46 R.L.P. b,% 13 45 13 15 11 11 9 14 8'. 01 7 23 6 80' ' 7 71 7 85 9 77 R.L.W.a,7„ 8 10 7. 83 6 83 5 62 4. 91 4 41 -. 4 10 4 65 4. 74 5 81 Carbohydrate Y i e l d a , % 52" 16 51. 66 54 61 55 .90 56. 45 56 58 56 18 55 69 55. 68 53 65 R e l a t i v e ^ Position", 7 7 8 ' 15 8 26 8 ' 40 8 46. 5 55 2 67 1 7.5 8 83. 9 91 3 12 Pulp Yield3,7= 54 25 56. 62 57 35 58 64 58. 25 58 87 58 26. 58 80 56. 51 57 13 55 80 55 13 57 82. 57 50 57. 86 60 79 58 56 57 76 57. 30 56 43 Averge , 7 . 55 03 55. 88 57. 59 58 07 58. 06 59 83 58 41 57 88 56. 91 56 78 R.L.P. b,% 7 .10 9. 04 10 28 9 22 6. 05 5 87 6 04 7 04 7. 25 6 92 R.L.W.a,7 4 31 5. 05 5 92 5 35 3. 51 3 46 3: 53 ' 4 07 4. 13 3 57 Carbohydrate Yield 3,7o " 50 72 " 50. 83 51 67 52 72 54. 55 55 41 54. 88 53 81 52. 78 53 21 R e l a t i v e ^ P o s i t i o n ,7, 5 3 18. 6 24 0 35 1 49. 4 61 3 70 0 81 2 88. 9 96 8 32 Pulp Y i e l d 3 , 7 43 51 44.45 47 12 44 50 49. 70 48 41 49 45 4.9 30 49. 90 47 13 44.11 43. 02 46 26 46 55 48. 25 48 70 .49 50 50 28 48. 90 48 31 Average, % 43 81 43 74 46 69 45 53 48. 98 48 56 49 25 49 79 49. 40 47 72 R.L.P . b ,7, 2 84 2. 30 2 44 1 66 1. 76 1 88 1 75 2 35 1. 86 1 88 R.L.W.a, 7o 1 24 1 01 .1 14 0 76 0. 86 0 91 0 86 r 17 ' 0. 92 0 90 Carbohydrate Y i e l d 3 , % 42 57 42 73 45 55 44 77 48. 12 47 65 48 39 48 62 48. 48 46 82 * : Relative p o s i t i o n from beginning of earlywood a : Based on extractive-free water-free wood b : Residual l i g n i n content based on water-free pulp Table 16. Sulphate raw pulp, r e s i d u a l l i g n i n and carbohydrate y i e l d s within Increment No. 47 (sapwood) of black spruce at one cooking time Cooking Relative, Time at P o s i t i o n " , % 5. ,6 16. ,9 27. ,8 36. ,1 45. ,1 54. 2 70.7 79. .9 88. ,6 97. 5 Max Min Pulp Yield a ,7= 53. ,54 56. ,62 58. ,00 57. ,20 58. ,79 60. 83 58. ,25 58. ,77 58. ,87 58. 00 12 54. .44 55. ,08 58, ,16 57, ,14 59, ,35 59. 01 58, ,24 59. ,47 59. ,74 58. 99 Average, 7, 53. ,99 55. ,85 58. ,08 57. ,17 59. ,07 59. 92 58. ,25 59. ,12 59. ,31 58. 50 R.L.P.b,7c 6. ,21 7, ,80 9. ,71 7. ,74 6. ,33 4. 12 2. .24 3. ,42 6. .44 4. 32 R.L.W.a,7o 3. ,35 4. ,36 5. ,64 4. ,42 3. ,74 2. 47 1. ,30 2. ,03 3. ,85 2. 52 Carbohydrate Y i e l d a , 7» 50. ,64 51. ,49 52. ,44 52. ,75 55. ,33 57. 45 56. ,95 57. ,09 55. ,46 55. 98 Relative p o s i t i o n from beginning of earlywood a : Based on e x t r a c t i v e - f r e e water-free wood b ; Residual l i g n i n content based on water-free pulp Table 17. Sulphate raw pulp, residual lignin and carbohydrate yields within Increment No. 30 (heartwood) of Douglas fir at three cooking times Cooking Time at Max Min Relative^ Position", 7o Pulp Yield 3,% 8.2 61.46 14. 65. 1 63 26 69 3 50 35. 70 4 73 44.8 70.15 60. 68. 7 81 70. 66. 3 67 76 66 7 88 82. 62. 1 73 90. 60. 6 28 3 63.70 64. 41 68 88 69 71 69 61 66 72 64 14 65 74 61 98 59 19 Average,?* 62.58 65 02 69 19 70 05 69 88 67 77 65 41 66 31 62 36 59 74 R.L.P.b,% 14.33 11 92 12 87 13 09 9 18 9 24 7 21 9 73 9 15 9 40 R.L,W.a,% 8.97 7. 75 8 90 9 17 6. 41 6 26 4 72 6 45 5 71 5 62 . Carbohydrate Yield a, % 53.61 57 27 59 56 60 88 63 47 61 51 60 67 59 86 56 65 54 12 Relative, Position ,7c 11.1 17 1 32 4 41 7 51 0 57 3 64 0 73 4 84 7 93 7 12 Pulp Yield3,7, 57.72 56 67 61 23 64.31 66 17 67 30 60 65 61 00 57 68 55 34 60.68 58 67 60 85 66 14 66 03 64 99 60 95 61 82 58 36 55 24 Average, 7, 58.20 57 67 61 04 65 23 66 10 66 15 60 80 61 40 58 02 55 29 R.L.P.b,7, 4.00 3 29 3 73 5 87 7 71 6 30 4 03 6 11 4 59 4 32 R.L.W.a,7> 2.32 1 90 2 28 3 83 5 10 4 17 2 45 3 75 2 66 2 39 Carbohydrate Yield 55.88 55 77 58 76 61 40 61 00 61 98 58 35 57 66 55 36 52 90 Relative^ Position ,7. 5.3 20.3 29 4 38 6 47 9 54 1 67 2 79 0 88 0 97 0 32 Pulp Yield a ,7 . 44.38 46 89 46 48 48 45 48 86 50 99 51 61 50 58 51 16 46 33 45.11 47. 74 45 51 49 33 50. 71 49 89 51 03 50 72 49 62 47 91 Average,?, 44.75 47 32 46 00 48 89 49 79 50 44 51 32 50 65 50 39 47 12 0.72 1. 04 0 94 1 08 1 13 0 82 0 75 0 67 0.97 0 53 R.L.W.a,7= 0.32 0. 49 0 43 0 53 0. 56 0 41 0 38 0 34 0 49 0 25 Carbohydrate Yield a, 7o 44.43 46. 83 45 57 48 36 49 23 50 03 50 94 50 31 49 90 46 87 * : Relative position from beginning of earlywood a : Based on extractive-free water-free wood b : Residual lignin content based on water-free pulp Table 1 8 . Sulphate raw pulp, residual l ignin and carbohydrate yields within Increment No. 5 7 (sapwood) of Douglas f i r at one cooking time Cooking Relative 5 . 4 1 5 . 4 2 9 . 0 3 7 . 3 4 8 . 2 5 6 . 3 6 4 . 8 7 6 . 4 8 8 . 3 9 7 . 1 Time at Position Max Min Pulp Y i e l d a , 7 o 5 0 . 6 5 5 5 . 5 0 5 8 . 1 6 6 0 . 2 2 6 0 . 1 3 6 0 . 6 8 5 9 . 5 2 5 8 . 4 6 5 7 . 1 6 5 4 . 0 1 1 2 5 1 . 7 0 5 5 . 8 5 5 9 . 4 5 6 0 . 5 3 6 0 . 6 6 6 1 . 3 4 5 9 . 6 7 6 2 . 1 6 5 7 . 7 4 5 3 . 5 4 Average, 7o 5 1 . 1 8 5 5 . 6 8 5 8 . 8 5 6 0 . 3 8 6 0 . 4 0 6 1 . 0 1 5 9 . 6 0 6 0 . 3 1 5 7 . 4 5 5 3 . 7 8 R . L . P . ,^ 7 . 3 0 7 . 8 6 8 . 5 5 8 . 9 4 7 . 9 6 6 . 3 9 5 . 3 9 5 . 1 7 5 . 2 6 5 . 3 7 R.L.W . a , 7 , 3 . 7 4 4 . 3 0 5 . 0 3 5 . 4 0 4 . 8 1 3 . 9 0 3 . 2 1 3 . 0 2 3 . 0 1 3 . 0 8 Carbohydrate Y i e l d a , 7 o 4 7 . 4 4 5 1 . 3 0 5 3 . 7 8 5 4 . 9 8 5 5 . 5 9 5 7 . 1 1 5 6 . 3 9 5 5 . 4 4 5 4 . 1 5 5 0 . 7 0 * : Relative position from beginning of earlywood a : Based on extractive-free water-free wood b: : Residual l ignin content based on water-free pulp Table 19. Na-base bisulphite raw pulp, residual lignin and carbohydrate yields within Increment No. 31 (heartwood) of1 black spruce at three cooking times. Cooking Relative Time at Position*, % 4.8 14.5 25.2 33.4 50.3 56.4 62.2 73.8 .87.1 95.0 Max Min 43 Pulp Yieldf 7, 76.03 69.42 72 72 06 78 70 69 44 62 73 73 52 03 72 73 28 23 67 68 24 91 64 65 47 84 64 66 28 15 62 63. 80 13 64 64-40 25 Average, 7, 72, 73 71 42 70 03 73 28 72 76 68 08 65 16 65 22 62. 97 64 33 R.L.P.b,7o • 17. 02 16 36 16.68 16 65 14 55 15 11 15 91 15 72 15 20 17 25 R.L.W.a,7o 12. 38 11 68 11. 68 12 20 10.58 10. 29 10 37 10 25 9. 57 11. 10 Carbohydrate Yie ld 3 ,7 60. 35 59 74 58/35 61 08 62 18 57 79 54 79 5.4 79 53. 40 53 23 Relative Position",7, 7. 3 12 1 30 7 38 7 47 3 59 2 65 1 76 4 81 7 .97 7 53 Pulp Yield3,7= 72. 57 68 63 70 96 71 51 69 70 62 09 62 55 64 95 58 78 62 00 • 69. 71 70 32 70. 03. 73 25 68 87 64 39 65 81 61 60 60 84 61 45 Aver age, 7, 71 14 69 48 70 50 72 38 69 29 63 24 64 18 63 28 59. 81 61 73 R.L.P.b,7= 16 81 16 45 16.23 15 50 14 53 13 30 14 94 14 00 15. 03 14 15 R.L.W.a,7o 11 96 11 43 11 37 11 21 10 07 8 41 9 59 8 86 5 42 8 73 Carbohydrate Yield a ,7 59 18 58 05 59 13 61 17 59 22 54 83 54 59 54'.42/. 54.39 53 00 Relative Position" ,7. 9 7 ,17 2 22 7 36 0 44 2 53 3 68 0 79 2 84.5 92 5 240 Pulp Yield 44 13 47 10 45 05 48 85 51 03 47 42 45 54 44 81 46 34 45 53 43 65 45 02 45 01 50 56 51 16 47 32 46 34 45 80 47 34 47 03 Average, 7, 43 89 46 06 45 03 49 71 51 10 47 37 45 94 45 31 46 84 46 28 R.L.P.b,7o 8" 85 8 64 5 '80 7 80 5 76 4 14 3 80 4 06 4 98 4 50 R.L.W. a,7, 3 89 3 98 2 61 3 88. 2 96 1 96 1 75 1 84 2 37 2 08 Carbohydrate Yield 3,7, 40' 00 42 08 42 42 45 83 48 39 45 41 44 19 43 47 45 14 43 .27 * : Relative position from beginning of earlywood a : Based on extractive-free water-free wood b : Residual lignin content based on water-free pulp Table 2 0 . Na-base bisulphite raw pulp, residual lignin and carbohydrate yields within Increment No. 4 7 (sapwood) of black spruce at one cooking time Cooking Relative^ Time at Position , 7 , 8 . 5 1 9 . 7 3 0 . 4 4 2 . 1 5 1 . 3 5 7 . 2 6 4 . 1 7 7 . 1 8 2 . 7 9 4 . . 6 Max Min Pulp Yie ld a ,7 0 5 0 . 2 5 5 1 . 0 1 5 0 . 5 1 5 6 . 6 4 5 7 . 9 2 5 5 . 4 8 5 3 . 0 4 5 3 . 3 0 5 2 . 5 2 5 1 . . 4 8 2 4 0 5 2 . 4 5 4 9 . 8 6 5 0 . 1 9 5 7 . 2 2 5 8 . 7 2 5 4 . 4 1 5 3 . 6 3 5 4 . 4 6 5 2 . 9 3 5 2 . . 2 6 Average, 7o 5 1 . 3 5 5 0 . 4 4 5 0 . 3 5 5 6 . 9 3 5 8 . 3 2 5 4 . 9 5 5 3 . 3 5 5 3 . 8 8 5 2 . 7 3 5 1 . , 8 7 R . L . P . b , 7 o 3 . 2 4 2 . 1 4 2 . 4 8 5 . 2 9 5 . 7 9 2 . 3 6 1 . 8 9 2 . 4 1 2 . 1 6 1 . , 6 1 R.L.W. a ,7 , 1 . 6 6 1 . 0 8 1 . 2 5 3 . 0 1 3 . 3 8 1 . 3 0 1 . 0 1 1 . 3 0 1 . 1 4 0 . . 8 4 Carbohydrate Yield a ,7= 4 9 . 6 9 4 9 . 3 6 4 9 . 1 0 5 3 . 9 2 5 4 . 9 4 5 3 . 6 5 5 2 . 3 4 5 2 . 5 8 5 1 . 5 9 5 1 . , 0 3 * : Relative position from beginning of earlywood a : Based on extractive-free water-free wood b : Residual lignin content based on water-free pulp Table 21. Na-base bisulphite raw pulp, residual lignin and carbohydrate yields within Increment No. 30 (heartwood) of Douglas fir at three cooking times Cooking Time at Max Min Relative^ Position ,7c. Pulp Yield a,7, 5. 82. ,4 ,52 14. 87. ,2 ,33 26. 85. ,0 ,79 34, 88. ,5 ,01 43. 87. ,2 ,96 62. 77. .3-,58 71. 77. .1 ,59 79. 78. ,8 ,60 88. 76. ,7 ,04 99. 77. .0 ,91 43 82. ,90 83. ,28 85. ,85 87, ,42 83. ,57 77. ,82 77. .93 79. ,04 76, .54 78, .24 Average ,7. 82. ,71 85. ,31. 85. ,82 87. ,72 85. ,77 77. ,70 77. ,76 78. ,82 76. ,91 78. ,08 R.L.P.b,7o 17. ,24 15. ,42 15. ,78 15. .93 14. ,80 14. ,96 12. ,52 12. ,85 13. .17 14.58 R.L.W. a,% 14. ,26 13. ,15 13. •54 14. ,61 9. ,26 11. ,92 9. .74 10. ,13 10. ,05 11. 38 Carbohydrate Yield 3 ,? 68. ,45 72. ,16 72. ,28 77. ,11 76. ,51 67. .78 68. .02 68. .69 66. ,24 66. ,70 Relative Position*,?, 2. ,4 17. 4 31. ,7 40. ,3^  53. ,4 59. ,5 68. ,2 76, .9 85. ,7 94. 7 53 Pulp Yield 3 ,? 81. ,51 81. 36 82. 96 82. ,95 77. ,96 75. 44 76. 94 76. •24 76. ,75 77. 69 79. ,51 82. ,67 83. ,67 82. ,06 81. ,00 78. ,56 75. ,04 77. .19 75. ,58 75. 78 Average,?, 80. ,51 82. ,02 83. 29 82. ,51 79. ,48 77. ,00 75. ,99 76. ,72 76. ,17 76. ,74 R . L . P . b , ? 16. ,09 • 14. ,22 13. 58 13. ,09 13. .78 12. ,34 12. ,70 12. ,75 13. ,17 13. .86 R.L.W. a,% . 12. ,95 11. 66 11. 31 10. ,80 10. ,95 9. ,50 9. ,65 9. ,78 10. ,03 10, ,64 Carbohydrate Yie ld 3 , 7o 67. ,56 70. ,36 71. 98 71. ,71 68. ,53 67. ,50 66. ,34 66. ,94 66. ,14 66, .10 Relative^ Position", 7, 8.. ,5 20. ,2 28. ,8 37. ,5 50.0 56. ,5 65. ,2 74. ,0 82. ,6 91. ,6 240 Pulp Yield 3,7 0 58. ,72 59. ,74 60.36 65, ,23 63. ,77 60. ,47 61. ,55 59, ,61 59. ,90 57, ,88 59! ,25 58. ,04 59. ,90 65. ,56 65. ,45 61. ,57 61. .66 60. ,04 59. ,93 58. ,35 Average,?, 58. ,99 58. .89 60. ,13 65, ,40 64. .61 61. .02 61, .61 59, ,83 59. .92 58, .12 R.L.P.b,7o 9. ,94 7. ,90 7. ,52 8. ,61 7. ,97 5. ,01 5, .25 3, .91 3. ,92 1, .79 R.L.W. 3 ,? 5, ,86 4. .64 4, ,52 5, ,63 5. .15 3, .01 3, .23 2 .34 2, .35 1, .04 Carbohydrate Yield a ,? 53. ,13 54. .24 55, ,61 59. ,77 59. .46 57, .01 58 .38 57, .49 57. .57 57, .08 * : Relative position from beginning of earlywood a : Based on extractive-free water-free wood b : Residual lignin content based on water-free pulp Table 2 2 . Na-base bisulphite pulp, residual lignin and carbohydrate yields within Increment No. 5 7 (sapwood) of Douglas fir at one cooking time Cooking Time at Relative, Position ,/c, 1 0 . 3 1 8 . 1 3 1 . 7 4 2 . 9 5 0 . 9 6 1 . 8 6 7 . 6 7 3 . 6 8 2 . 4 9 4 . 2 Max Min Pulp Yield a ,°/ 0 5 6 . 1 1 5 2 . 2 8 6 5 . 5 1 6 5 . 0 4 6 8 . 2 2 5 6 . 2 3 5 5 . 3 3 5 5 . 5 9 5 6 . 2 2 5 3 . 2 1 2 4 0 5 3 . 3 9 5 3 . 0 0 6 8 . 8 0 6 2 . 5 4 6 4 . 6 0 5 5 . 9 4 5 5 . 4 5 5 5 . 1 3 5 5 . 8 1 5 2 . 6 0 Average 5 4 . 7 5 5 2 . 6 4 6 7 . 1 6 6 3 . 7 9 6 6 . 4 1 5 6 . 0 9 5 5 . 3 9 5 5 . 3 6 5 6 . 0 2 5 2 . 9 1 R.L.P. , /o 7 . 9 9 2 . 1 5 1 0 . 9 8 8 . 1 2 9 . 7 6 3 . 2 7 3 . 1 2 2 . 8 6 3 . 3 7 2 . 7 4 R.L.W. a ,7> 4 . 3 7 1 . 1 3 7 . 3 7 5 . 1 8 6 . 4 8 1 . 8 3 1 . 7 3 1 . 5 8 1 . 8 9 1 . 4 5 Carbohydrate Yield a ,7c 5 0 . 3 8 5 1 . 5 1 5 9 . 7 9 5 8 . 6 1 5 9 . 9 3 5 4 . 2 6 5 3 . 6 6 5 3 . 7 8 5 4 . 1 3 5 1 . 4 6 Relative position from beginning of earlywood Based on extractive-free water-free wood Residual lignin content based on water-free pulp Table 23. Regressions of micro-specific gravity on position within growth increments Curvilinear regression equations R i n Y „ Black spruce Increment No. 31 (heartwood) •1.09-0.24-10"1x1 + 0.81-10~3X2 - 0.51-10~5x3 Black spruce Increment No. 47 (sapwood) •1.07-0.38-10_1x2 + 0.11-10"2x2 - 0.65-10_5x2 0.98 0.04 0.98 0.04 An Y, in Y, Douglas f ir Increment No. 57 (sapwood) •1 .23-0 .42«10' 1 x 3 « + 0.13-10_ 2x3 - 0.81-10~5x3 0.99** 0.05 Douglas f ir Increment No. 57 (sapwood) •1.25-0.30-10"1x. + 0.11-10"2x2 - 0.84-10_ 5x3 0.98** 0.06 4 4 4 CO Micro-specific gravity based on extractive-free water-free weight and green volume : % relative position within growth increment, from beginning of earlywood Significant at 0.01 probability level Table 24. Regressions of wood lignin on position within growth increments Curvilinear regression equations R Black spruce Increment No. 31 (heartwood) Y l " 3. .20 + 0.51-10"2Xl - 0.19-10"3x2 + 0.13-10~5X3 Black spruce Increment No. 47 (sapwood) 0.93 0.92 Jin Y2 = 3. ,23 + 0.32-10"2x2 - 0.18-10_3x2 + 0.13-10~5x3 Douglas fir Increment No. 30 (heartwood) ** 0.97 0.54 Y3 = 3. ,43 - 0.16-10_ 2X / - 0.99-10"4x2 + 0.88-10"6x3 4 4 4 Douglas f ir Increment No. 57 (sapwood) ** 0.93 1.06 i n Y4 = 3. ,27 + 0.56-10~2x, - 0.25-10_3x2 + 0.18-10_ 5x3 4 4 4 ** 0.99 0.37 Y. : % wood lignin content based on extractive-free water-free weight and l green volume : 7o relative position within growth increment, from beginning of earlywood ** : Significant at 0.01 probability level Table 25. Regressions of sulphate pulp yield on position within growth increments R SE, Cooking Time, min Curvilinear regression equations 3 12 32 i n Y± X n Y 0 Black spruce Increment No. 31 (heartwood) 4.08 + 0.16-10"^ + 0 .21«10" 4 x 2 + 0.50-10~7x3 = 3.98 + 0.33-10"2x 0.29-10"4x2 - 1.00-10"8x3 3.77 + 0.56-10"3x3 + 0.55'10"4x3 - 0.52'10"6x3 Black spruce Increment No. 47 (sapwood) 0.75N S 0.61 ** 0.94 0.95 *rt 0.94 0.57 12 J?n Y, = 3.96 + 0.45-10 x, / 0 C\ Q 0.55*10" x. + 0.21-10" x7 4 4 ** 0.94 0.75 Douglas f ir Increment No. 30 (heartwood) 3 12 32 i ? n Y 5 -f n Y 6 = ^ n Y 7 -4.07 + 0.94-10 "x5 •« 0.14-10_ 3x2 + 0.40'10"6x3 -2 •2 3.96 + 0.78-10 "x, - 0.73-10"4x2 - 0.62-10_7x3 6 6 6 3.81 - 0.11-10"3x7 + 0.86-10_4x7 - 0.81-10"6x3 Douglas fir Increment No. 57 (sapwood) 0.98 0.93 0.92 0.80 rt* 0.95 1.89 12 i n Y, = 3.90 + 0.82-10 xr 0.86«10"4 x 2 + 0.11-10~6x3 o o rtrt 0.98 0.87 7. pulp yield based on extractive-free water-free wood X, : 7. relative position within growth increment, from beginning of earlywood Significant at 0.01 probability level Non-significant rt* NS Table 26. Regressions of Na-base bisulphite pulp yield on position within growth increments Cooking „ Time, min Curvilinear regression equations E 240 Black spruce Increment No. 31 (heartwood) •2 • l f t 1 n - 3 2 . „ r „ , -6 3 43 i n Y g = 4.26 + 0.33-lo"x 9 - 0.10-10 x 2 + 0.58-10"~Xg 0.89 2.19 S3 J?n Y 1 Q = 4.20 + 0.75-10~2x1 ( ) - 0.21'10 _ 3x^ 0 + 0.12•10~ 5x 3 0 0.95** 1.78 240 i n Y n = 3.64 + 0.15* l O - 3 ^ - 0.28* l O ^ x ^ + 0.16-lO^x3^ 0.82NS Black spruce Increment No. 47 (sapwood) 1.54 240 #n Y 1 2 = 3.89 + 0.26-10 _ 2x 1 2 + 0.13-10~4x22 - 0.37'10~6x32 0.70NS 2.35 Douglas f ir Increment No. 30 (heartwood) 43 i>n Y 1 3 = 4.38 + 0.75-10"2x13 - 0.19'10"3x23 + 0.11'10 _ 5xJ 3 0.95** 1.51 53 | n Y . . = 4.37 + 0.49 'lo" 2x,. - 0.14'10"3x2 + 0.89'10_ 6x3 0.96** 0.92 14 14 14 14 240 %a. Y 1 5 = 4.01 + 0.57.10"2x15 - 0.75-10~4x25 + 0.20-10~ 6 x 3 5 0.77NS 1.98 Douglas f ir Increment No. 57 (sapwood) i n Y , , = 3.72 + 0.28'10 - 1x., - 0.52'10"3x2 + 0.27'10"5x3 0.82NS 3.71 io 16 16 16 y. : % pulp yield based on extractive-free water-free wood : 7o relative position within growth increment, from beginning of earlywood * : Significant at 0.05 probability level ** : Significant at 0.01 probability level NS : Non-significant Table 27. Regressions of sulphate pulp carbohydrate yields on position within growth increments Cooking R S E Time, min Curvilinear regression equations E Black spruce Increment No. 31 (heartwood) 3 J(n Y 1 ? = 3.93 + 0.14-10~2x17 + 0.34'10~4 X 2 7 - 0.45-10~6x37 0.95** 0.69 12 Jin Y 1 Q = 3.91 + 0.69-10 _ 3x 1 o + 0.42-10~4x2 - 0.48-10~6x3 0.92** 0.90 lo lo lo lo 32 , J(n Y 1 9 = 3.74 + 0. 79 • 10"3 X ; L Q + 0.59- lo" 4 X 2 g - 0.58-10~6x39 0.95** 0.79 Black spruce Increment No. 47 (sapwood) n -3 -4 2 -6 3 * * 12 J(n Y 2 Q = 3.91 + 0.70-10 x 2 Q + 0.51-10 x 2 Q - 0.50-10 x 2 Q 0.96 0.93 Douglas f ir Increment No. 30 (heartwood) 3 /fn Y 2 1 = 3.93 + 0.81'l6~2x21 - 0.73'lo" 4x 2 1- 0.97'10"7x21 0.98** 0.84 12 | n Y 2 2 = 3.94 + 0.70-10"2x22 - 0.75*10"4x22 + 0.31-10 _ 7x 3 2 0.95** 0.75 32 Jin Y 2 3 = 3.80 - 0.40-10 _ 3x 2 3 + 0.92-10'4x2 3 - 0.84-10 _ 6x 2 3 0.96*** 1.13 Douglas f ir Increment No. 57 (sapwood) 12 /n Y 0 / = 3.83 + 0.66-10 - 2x o / - 0.48-10"4x2 - 0.10-10 _ 6 X 3 0.99** 0.61 24 24 24 24 Y. l X. l ** % pulp carbohydrate yield based on extractive-free water-free wood % relative position within growth increment, from beginning of earlywood Significant at 0.01 probability level Table 28. Cooking Time, min Regressions of Na-base bisulphite pulp carbohydrate yields on position within growth increments Curvilinear regression equations R 43 53 240 240 43 53 240 240 Black spruce Increment No. 31 (heartwood) o c - 4.07 + 0.30-10 _ 2x o, - 0.80-10_4x2 + 0.38-10_ 6x3 ID ID ID 25 4.03 + 0.59 10"2xo, - 0.15 10~ 3 X 2 + 0.85 10~6x3 lo 26 26 3.56 + 0.14.10 _ 1x 2 7 - 0.24.10 _ 3x 2 7 + 0.11-10 _ 5x 3 7 Black spruce Increment No. 47 (sapwood) 3.88 + 0.13-10"2xOQ + 0.34'10"4x2 - 0.45'10"6x3 Douglas f ir Increment No. 30 (heartwood) 4.17 + 0.11-10 - 1x 2 9 - 0.23'10"3x29 + 0.12'10~5x29 4.20 + 0.62-10 _ 2x 3 0 - 0.15-10"3x20 + 0.90-10 _ 6x 3 0 3.91 + 0.67-10"2x31 - 0.89'I0"4x2 0 + 0.35'10"6x31 Douglas fir Increment No. 57 (sapwood) Y 3 2 = 3.72 + 0.21-10"1x32 - 0.37'10~3x32 + 0.19'10"5x32 Xn Y ^ Y26 ^ Y27 j?n Y ^ Y29 Y 3 Q J?n Y 3 1 0.87* 2.04 0.92 0.90 0.79 NS 0.91 0.96 0.87 0.90 1.38 1.29 1.53 2.06 0.75 1.32 1.85 % pulp carbohydrate yield based on extractive-free water-free wood j. : 7o relative position within growth increment, from beginning of earlywood Significant at 0.05 probability level Significant at 0.01 probability level NS : Non-significant 29A. 29B. 29. Analysis of variance on species, wood zone and species-wood zone interactions for raw pulp, residual lignin and carbohydrate yields in sulphate pulping (12 Sulphate raw pulp yield based on water-•free wood Source DF SS MS F Species 1 30.287 30.287 3.95N S Wood zone 1 17.541 17.541 2.29N S Species Wood Zone 1 32.611 32.611 4.26* Error 36 275.951 7.665 Total 39 356.390 Sulphate pulp residual lignin based on water-free wood Source DF SS MS F Species 1 0.946 0.946 0.87N S Wood Zone 1 0.006 0.006 0.01N S Species X Wood Zone 1 8.055 8.055 ** 7.38 Error 36 39.273 1.091 TQtal 39 48.280 I VO 29C. Sulphate pulp carbohydrate yield based on water-free wood Source DF SS MS F Species 1 39.57 39.57 * 5.52 Wood Zone 1 1.91 1.91 0.27NS Species X Wood Zone 1 "81.73 81.73 ** 11.40 Error 36 258.05 7.17 Total 39 381.26 * : Significant at 0.05 probability level ** : Significant at 0.01 probability level NS : Non-significant Table 30. Analysis of variance on species, wood zone and species-wood zone interactions for raw pulp, residual lignin and carbohydrate yields in Na-base bisulphate pulping (240 min max) Na-base bisulphite raw pulp yield based on water- free wood Source DF SS MS F Species 1 877.42 877.42 73.56"' Wood Zone 1 37.34 37.34 3.09N S Species X 1 223.91 223.91 ** 18.56 Wood Zone Error 36 434.31 12.06 Total 39 1572.98 Na-base bisulphite residual lignin based on water -free wood Source DF SS MS F Species 1 18.91 18.91 ** 7.86 Wood Zone 1 6.50 6.50 2.70N S Species X 1 1.08 1.08 0.45N S Wood Zone Error 36 86.58 2.41 Total 39 113.07 30C. Na-base bisulphite carbohydrate yield based on water-free wood Source DF SS MS F Species 1 630.84 630.84 ** 95.84 Wood Zone 1 77.77 77.77 ** 11.82 Species X 1 251.14 251.14 ** 38.16 Wood Zone Error 36 236.14 6.58 Total 39 1195.89 ** : Significant at 0.01 probability level NS : Non-significant Table 31. Analysis of variance on species, growth zone and species-growth zone interactions for raw pulp, residual lignin and carbohydrate yields in sulphate pulping by combining cooking times and wood zones 31A. Sulphate raw pulp yield based on water-free wood Source DF SS MS F Species 1 126.93 126.93 3.17N S Growth Zone 1 3.35 3.35 0.08NS Species X 1 17.44 17.44 0.44NS Growth Zone Error 76 3045.00 40.07 Total 79 3192.72 Sulphate pulp residual lignin based on water-free wood Source DF SS MS F Species 1 0.40 0.40 0.08NS Growth Zone 1 21.58 21.58 * 4.42 Species X 1 0.19 0.19 0.04NS Growth Zone Error 76 370.72 4.88 Total 79 392.89 VO 31C. Sulphate pulp carbohydrate yield based on water-free wood Source DF SS MS F Species 1 119.13 119.13 5.65 Growth Zone 1 6.91 6.91 0.33N S Species X 1 16.79 16.79 0.80NS Growth Zone Error 76 1602.30 21.08 Total 79 1745.13 * : Significant at 0.05 probability level ** : Significant at 0.01 probability level NS : Non-significant Table 32 Analysis of variance on species, growth zones and species-growth zone interactions for raw pulp, residual lignin and carbohydrate yields in Na-base bisulphite pulping by combining cooking times and wood zones 32A. Na-base bisulphite raw pulp yield based on water-free wood Source DF SS MS F Species 1 2457.20 2457.20 ** 22.46 Growth Zone 1 264.27 264.27 2.42N S Species X 1 145.25 145.25 1.33NS Gowth Zone Error 76 8316.30 109.43 Total 79 11183.02 Na-base bisulphite pulp residual lignin based on water-free wood Source DF SS MS F Species 1 26.06 26.06 1.43NS Growth Zone 1 69.56 69.56 3.81N S Species X 1 7.98 7:98 0.44NS Growth Zone Error 76 1387.80 18.26 Total 79 1491.40 Na-base bisulphite pulp carbohydrate yield based on water-free wood Source DF SS MS F Species 1 2021.00 2021.00 ** 44.17 Growth Zone 1 72.11 72.11 1.58NS Species X 1 76.04 76.04 1.66NS Growth Zone Error 76 3477.60 45.76 Total 79 5646.75 NS Significant at 0.01 probability level Non-significant - 99 -Radiol Dislance.rnm-Heartwood Increment No- 3 0 B 70 -65 60 -5 0 -4 5 -4 0 -^ S8% . latewood t Sapwood Increment No-57 Pseudotsuga memiesii ( M i r b ) F r a n c o Sulphate Time m a x , min- 3 12 3 2 Raw Pulp — • — — « — — • — Carbohydrate ••••o- e - 0 8 •0-7 - 0 6 0 5 - 0 4 - 0 3 - 0 - 2 I i L _L 2 0 4 0 6 0 8 0 100 0 2 0 4 0 Relat ive Posit ion Within Inc rement ,% -I 1 l_ 6 0 8 0 100 4 0 Radial Distance.mm-Fig. 1 , Relationship between various sulphate raw pulp and relative position within growth increments spruce and Douglas fir factors of black - 100 -Piceo mono no (Mill)B- S P No-bisulphite Time max- ,min- 53 240 Raw Pulp — Carbohydrate • o • > 60 Radiol D i s t o i c a . m m Fig. 2 . Relationship between various Na-base bisulphite raw pu factors and relative position within growth increments of black spruce and Douglas fi r 

Cite

Citation Scheme:

        

Citations by CSL (citeproc-js)

Usage Statistics

Share

Embed

Customize your widget with the following options, then copy and paste the code below into the HTML of your page to embed this item in your website.
                        
                            <div id="ubcOpenCollectionsWidgetDisplay">
                            <script id="ubcOpenCollectionsWidget"
                            src="{[{embed.src}]}"
                            data-item="{[{embed.item}]}"
                            data-collection="{[{embed.collection}]}"
                            data-metadata="{[{embed.showMetadata}]}"
                            data-width="{[{embed.width}]}"
                            async >
                            </script>
                            </div>
                        
                    
IIIF logo Our image viewer uses the IIIF 2.0 standard. To load this item in other compatible viewers, use this url:
http://iiif.library.ubc.ca/presentation/dsp.831.1-0104182/manifest

Comment

Related Items