Effect of Cationic Hemicellulosic Fractions from Corncob Obtained by Graded Ethanol Precipitation on Recycled Paper Strength

Abstract

This study investigated how various hemicellulosic fractions extracted from corncob, which have different chemical structures, affect paper strength properties when derivatized and used as paper strengthening agents. Four hemicellulosic fractions with different molecular weights and heteropolymer branching were extracted from corncob via a selective precipitation process; afterwards, the fractions were then chemically modified to obtain cationic hemicelluloses, which were used as strengthening agents for recycled pulp papermaking. These cationic hemicellulosic fractions improved the mechanical strengths of handsheets composed of recycled fibers and paper machine white water fines; however, the level of improvement was different among the fractions. Cationic hemicellulosic fractions showed a better improvement on the strength of handsheets without fines than that of the handsheets with fines. Especially, cationic hemicellulosic fraction obtained from 30% ethanol aqueous medium had the highest molecular weight and the highest substitution degree and thus showed the best enhancement in the mechanical strength of handsheets. Hence, this work demonstrates how to utilize hemicelluloses efficiently as strength agents for recycled pulp papermaking.