Differences of Chemical and Physical Properties on Fractionated Dissolving Pulp During Alkalizing and Aging Process

Abstract

In recent years, there has been a consistent increase in viscose staple fiber (VSF) production, leading to an increased demand for dissolving pulp among producers. The properties of the pulp play a crucial role in influencing the efficiency of viscose operation, necessitating the selection of efficient raw materials. Therefore, this study aimed to evaluate the differences in chemical properties, fiber morphology, and viscose performance of fractionated pulp during alkalizing and aging processes. Alkalizing and aging were carried out under similar conditions for all fractions tested. The pulp samples consisted of reference (REF), long-fiber (LF), medium fiber-long (MFL), medium fiber-short (MFS), and short-fiber fractions (SF). The chemical analysis results showed that SF had the lowest viscosity, alpha-cellulose, and molecular weight. Physical properties of SF also had the lowest cell wall thickness (CWT), cross-section area (CSA), and coarseness, but it had the highest fiber population and water retention value (WRV) compared to LF. These characteristics significantly affected the quality of alkaline cellulose and the degree of polymerization rate during the aging process. SF showed the fastest depolymerization time (145 minutes) to achieve a target viscosity of 240 mL/g compared to others (192–194 minutes). However, aging rate was constant for all the samples examined. Based on the results, MFL was considered the ideal fraction for the viscose process due to its suitable fiber characteristic, leading to good behavior in alkalizing and aging. The samples also had an acceptable initial viscosity (478 mL/g) and a predominant fraction yield (30%), showing enhanced productivity.

Keywords

• aging
• alkalizing
• dissolving pulp
• fractionation
• viscose