Structural characterization of cellulose pulp in aqueous NMMO solution under the process conditions of lyocell slurry

Abstract

A systematic structural characterization of dissolving grade cellulose pulp in aqueous NMMO solution is performed under the process conditions of lyocell slurry. Different types of cellulosic pulps such as hard/soft wood and acid sulfite/kraft sulphate pulps are used for the present study. The structural changes of pulp in lyocell slurry at different temperatures are characterized in terms of dimension, interstitial spaces, crystallinity using Optical (weight and thickness gain), SEM and XRD measurement technique, respectively. It was observed that kraft sulphate pulp has higher weight gain and lower thickness gain compared to acid sulphite pulps due to its pulping process chemistry. These results are further supported by SEM and XRD analysis. It is also found that above 50 °C, hardwood kraft sulphate pulp shows homogeneous and consistent swelling compared to other pulp combinations. These findings are commercially useful, because, homogeneous swelling of pulp is one of the essential parameters of slurry preparation.