Population balance based modeling of changes in cellulose molecular weight distribution during ageing

Abstract

Ageing is an important processing step in viscose fiber production. The degree of polymerization of viscose solution is controlled by ageing of alkali cellulose for desired fiber properties. In this work, alkali cellulose was treated under typical ageing conditions for different time periods. The changes in the molecular weight distribution due to the ageing reactions were analyzed by size exclusion chromatography with multi-angle laser light scattering detection. Furthermore, a population balance based approach to model the evolution of the molecular weight distribution during cellulose ageing is introduced. Several scission rate models capable of predicting the evolution of the molecular weight distribution are proposed and evaluated against the experimental data. The comparison of results from different models revealed that the scission rate of polymers is a function of the degree of polymerization and ageing time period. This modelling approach provided the possibility of more accurate and efficient solution than the previous similar models.