Insights into activation of dissolving pulp preceding cellulose acetylation

Abstract

The current study was conducted to identify the most important variables in the activation phase of cellulose acetate production. Dry alpha cellulose pulp as raw material was supplied by a local company with the intrinsic properties of viscosity equal to 926 mL/g and a water content of 96%. In this regard, the activation phase variables, including reaction time (T30, T60, and T90 min), the addition level of acetic acid (C25, C35, and C45 units per 100 units of dry cellulose), and sulfuric acid catalyst (H0, H0.1, H0.5, and H1%), were experimented followed by characterization of the activated pulp properties through water retention value (WRV), carboxyl groups, viscosity, reactivity, and Fourier transform infrared (FTIR) spectroscopy analysis of fibers. The results indicated that cellulose activation is a complex process with an inverse or contributing effect of the variables. The data were extensively discussed considering the swelling effects governed by diffusion and chemical reactions in both crystalline and amorphous regions of fibers. Eventually, those findings conveyed that the activation process with the above-mentioned conditions was able to improve the properties of cellulose for acetylation phase particularly by increasing reaction time in acid acetic and H2SO4 catalyst consumption.