Strengthening effects of carboxymethylated hemicellulosic fractions on paper strength

Although hemicelluloses have demonstrated their promising application as paper strengthening agents, the influences of different hemicellulosic fractions on the mechanical properties of paper are not clear. Revealing the reinforcing effect of hemicellulosic fractions on the mechanical properties of paper is very helpful to better utilize hemicelluloses. For this purpose, four hemicellulosic fractions (HCpH5.5, HC15%, HC30%, and HC75%) were extracted from corncob, and then chemically modified (carboxymethylation) as paper strengthening agents. We demonstrated that the hemicellulosic fraction HC55% obtained from 15% ethanol was difficult to be modified; while HC75% obtained from 75% ethanol was more easily chemically modified. Furthermore, the carboxymethylated hemicellulosic fraction CHC30% with fewer branches and the highest molecular weight had a more significant effect on improving paper strength. Therefore, isolation of desirable hemicellulosic fraction is extremely important to more effectively apply hemicelluloses as paper strengthening agents.