Changes of Strength Properties of Wood Pulp with Cellulase Treatment

Abstract

High α-sulfite pulp was hydrolyzed with powdered cellulase, and the changes of paper strength and some variables assumed to affect the strength were studied. Tensile strength increased initially with the time of cellulase treatment and it showed aa maximum value. The maximum became considerably higher with beating degree of the pulp. Tear strength decreased with the time of cellulase treatment. However, in the case of beatenn pulps, the smaller decrease in tear strength was observed as compared to that of unbeaten pulp with cellulase treatment. When the beaten pulp with beating degree 37°SR was treated with cellulase, the maximum breaking length was about 75% higher than that obtained with beating, whereas the tear factor was almost unchanged. The changes of characteristics including viscosity-average DP, number-average fiber length, WRV, pentosan content, fiber length distribution, fine fiber content and specific volume of paper web were studied to investigate their influence on the paper strength. It was concluded that these changes in tensile and tear strength might be interpreted by the fact that only a part of pulp fibers was hydrolyzed with cellulase treatment and a number of fibers were formed which, with regard to interfiber bonding, played an important role particularly in such materials as the high α-sulfite pulp which was less swellable.