Changes of Strength Properties of Wood Pulps with Cellulase Treatment

Abstract

Bleached Kraft paper pulp (KP) was hydrolyzed with powdered cellulase, and the changes of paper strength and some characteristics assumed to affect strength propertise were studied. Both of tensile and tear strength considerably decreased with the time of cellulase treatment, while those in high-α sulfite pulp (SP) increased. The changes of characteristics including cellulase treating yield, water retention value (WRV), fine content, specific volume of the web, pentosan content and number-average fiber length were studied to investigate their influence on the paper strength properties. As a consequence, it was presumed that these differences in changes of strength properties and other characteristics between KP and high α-SP were caussed by the reasons as follows : (1) the changes in WRV and fine content of KP with cellulase treatment were little and the number-average fiber length was lowered, (2) the changes in WRV and fine content with cellulase treatment affect hydrogen bonding only a little, since KP has larger swellability and web had more amount of interfiber hydrogen bonds originally, and (3) the degree of entanglement of fibers and the single fiber strength properties were higher in the case of KP, so the lowering of fiber length affected tensile and tear strength more severely. Thus, it was concluded that the differences in the changes of strength and other characteristics with cellulase treatment between KP and high α-SP depend mainly upon the swellablity of each fiber.