MODIFICATION OF DOUGLAS-FIR MECHANICAL AND KRAFT PULPS BY ENZYME TREATMENT

A cellulase enzyme preparation was assessed for its potential to enhan ce the fiber characteristics of mechanical and kraft pulps derived fro m Douglas-fir. The effect of enzyme treatment on pulp properties varie d with enzyme dosage. A charge of 1 mg protein per gram of ovendry pul p improved handsheet density and smoothness, increased pulp freeness, and reduced fiber coarseness while only slightly diminishing sheet str ength properties. In general, fiber-length fractions showed the same r esponse to treatment as the unfractionated whole pulp. However, tensil e strength for the kraft fiber fractions increased with enzyme treatme nts, while the whole pulp suffered a slight decline. This suggests the possibility of improving pulp properties by selective treatment of in dividual fiber fractions.