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The use of raifix to enhance fines and filler retention in mechanical groundwood pulps Trigylidas, Dennis

Abstract

This work investigates the use of Raifix as a retention enhancing ATC in clay and PCC filled mechanical groundwood pulp suspensions. Raifix is a starch based Anionic Trash Collector (ATC) which is patented and produced by Raisio Chemicals of Finland. Raifix coagulates the anionic Dissolved and Colloidal Substances (DCS) present in a pulp furnish and attaches them to the fibre. These are subsequently flocculated by a high molecular weight retention aid polymer. In this work, Raifix was used in conjunction with a Poly(ethylene oxide)-Phenol Formaldehyde Resin (PEO-PFR) retention aid system. In first pass retention experiments conducted with a Dynamic Drainage Jar (DDJ), when Raifix was added prior to PFR and PEO, the retention of fines and clay increased by as much as 18% and 31% respectively. In contrast, Raifix had a detrimental effect on retention in the PCC filled pulp suspension. In both cases, the cationic demand and turbidity of the DDJ filtrate (analogous to a mill's white water) decreased as Raifix dosage was increased. Laser diffraction particle size analyses were also performed to observe the aggregation behaviour of clay and PCC filler. When Raifix was added prior to PFR and PEO, the rate of aggregation and aggregate size of clay increased by as much as 1000% and 150% respectively. Once again, Raifix had a detrimental effect on PCC aggregation. Finally, experiments were performed using Fourier Transform Infrared Analysis to observe the molecular interactions between PEO, PFR and Raifix. The results of these experiments show evidence of hydrogen bonding interactions between PEO and PFR as well as Raifix and PFR. This was indicated by a shift of the hydrogen bonded O-H peak to a lower frequency.

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