UBC Theses and Dissertations
Providing termite and fungal protection to waferboard using novel termiticides and fungicide Fang, Zhijuan
The compatibility of eight liquid PF resins and one pMDI-resin with three termiticides and two fungicides, provided by Dr. Wolman GmbH, was evaluated by measuring changes in gelation time and viscosity. The results indicate that the termiticides are generally compatible with the phenolic resins and the pMDI-resin. The fungicides were only compatible with two phenolic resins and neither was compatible with the pMDI-resin. Based on these results it was concluded that the three termiticides would be fully compatible with the two liquid phenolic based resins, BB7028, and GP70CR66, and the pMDI-resin and can be incorporated into these resins as a glue-line additive during waferboard manufacture. The fungicides were found not to be compatible in the resins and thus would have to be applied onto the strands separately from the resins. Even then they may cause some interference with the glue curing. The fungicide, formulated with both K H D O and fenpropimorph, were sprayed onto strands during the manufacture of the waferboard at the same time as the resin but using a separate spray line, enhanced the waferboard durability against both brown and white rot fungi. The mass losses of the test blocks cut from the boards manufactured with different concentrations of fungicide and exposed to four decay fungi, suggested that, 0.44 % KHDO and fenpropimorph (based on the oven dry weight of the strands) provided the same protection from two white rot (T. versicolor and P. ostreatus) and two brown rot fungi (G. trabeum and P. placenta) attacks as waferboard which incorporated 0.83 % zinc borate. The fungicide was most effective against the brown rot fungi, while a toxic threshold of 0.29 % KHDO and fenpropimorph was observed. For the two white rot fungi the toxic threshold was determined to be 0.44 % KHDO and fenpropimorph. At all concentrations the fungicide had no adverse effect on the static bending strength of the waferboard, but caused a slight (17 %) loss in internal bond strength. The mechanical strength loss of samples heeded in this way was much lower than the mechanical strength loss of commercial 1 % zinc borate treated boards tested tested in the same manner. Based on data generated in this study and commercial information on untreated waferboard, 0.83 % zinc borate caused a 7.13 % loss in MOE, a 14.98 % loss in MOR and a 21 % loss in IB strength. Based on all of the results of decay testing and mechanical strength evaluation, it may be concluded that the fungicide, at 0.44 % active ingredient, could be sprayed onto furnish simultaneously for the GP70CR66 and GP265C54 PF-resins for manufacturing waferboard to improve its fungal resistance without causing significant reduction in strength. The three termiticides, LP 15406A, LP 15406B, and LP 15447, were sprayed onto the furnish as an additive by dissolving in the BB7028, and GP70CR66 liquid PF-resins. None of the three termiticides had any significant effect on IB strength. However, static bending strength was affected. LP 15406A did not negatively affect MOE, but did cause a slight reduction in the mean value of the MOR. However, this change was not statistically significant. LP 15406B had no affect on the waferboard MOR, but significantly increased the MOE; a similar trend was also noted for the LP 15447. These results suggest that all three termiticides can be considered as suitable additives to liquid resins during the manufacture of termite resistant boards, over the range of concentrations evaluated in this research. Based on the results for the pMDI-resin waferboard which incorporated the three termiticides, the mechanical strength data indicates that, LP 15406B, with 0.0073 % chlorfenapyr content in waferboard is the most promising termiticide because it had no effect on the mechanical properties of the waferboard. LP 15406A, with 0.0052 % bifenthrin content in waferboard, could be added to pMDI-resin. However, more research is needed since it did cause a 12 % mean reduction in the internal bond strength, although this reduction was found to be not statistically significant. LP 15447, with 0.0052 % 5-amino-l-[2,6-dichloro-4-(trifluoromethyl)phenyl]-4-[(lR,S)-(trifluoromethyl)sulfinyl]- lH-pyrazol-3-carbonitrile caused a 37 % reduction in the mean internal bond strength and therefore is not suitable for addition to pMDI in waferboard manufacture.
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