Effects of cationic starch addition and pulp beating on strength properties of softwood kraft pulp

Abstract

In this study, cationic starch (CS) was added to softwood kraft pulps at different degrees of beating in order to evaluate their effects on the strength properties of the pulp. Handsheets were prepared by using three levels of CS addition (0.75, 1.5, and 2.25% CS with respect to oven-dry pulp) to kraft pulps at different beating degrees (15, 20, 25, and 30 degrees SR). It was found that the tensile and burst indices improved with beating, CS addition, and a combination of these two applications, while the tear index decreased. Remarkable increases in burst and tensile indices were achieved with a 0.75% addition of CS to 15 degrees SR and 20 degrees SR pulps, while notable decreases in tear index was obtained at the same conditions. A gradual tendency was observed in higher beating degrees (25 SR and 30 degrees SR) and higher CS additions (1.50 and 2.25%).