PROPERTY ENHANCEMENT OF KRAFT-BASED DISSOLVING PULP BY COMBINING PULP FRACTIONATION AND CELLULASE TREATMENT

摘要

A narrow molecular weight distribution(MWD)and high reactivity are highly desired to obtain a high-quality dissolving pulp.Cellulase treatment can improve the properties(e.g.,reactivity,MWD)of kraft based dissolving pulp; however,the conventional single-stage cellulase treatment of whole pulp led to inhomogeneous results due to the preferable adsorption of cellulase onto the short fibers/fines.In this study,a sequential process consisting of pulp fractionation,followed by cellulase treatment of each fraction,aiming to improve the MWD and reactivity of a prehydrolysis kraft(PHK)pulp,was investigated.Three pulp fractions,namely long-fiber fraction(LF),mid-fiber fraction(MF)and short-fiber fraction(SF),were obtained from a PHK sample.The results showed that the SF had the lowest viscosity,highest accessibility and cellulase adsorption,while the opposite was true for the LF.At a given viscosity level,the newly proposed sequential process led to a lower PDI(3.71 vs 4.98)and a higher Fock reactivity(85.6％vs 76.3％)in comparison to the conventional single-stage cellulase treatment on the whole pulp.