Factors affecting crystalline structure of cellulose during solvent purification treatment

The influence of acetone, as a solvent on crystalline structure of the cellulose, was investigated. Crystalline changes brought about by the solvent treatment on the residual cellulose have been found to be noticable. The crystallinity index of solvent treated celluloses has shown a trend of a small gradual increase with the progressive increase of acetone concentration in the treatment. The crystallite size of the residual cellulose has also been found to decrease successively with the increase of acetone content in the solvent composition. While the decrease in crystallite size reached approximately 8 %, the equivalent weight loss was only about 0.9 %. The influence of kinetic parameters on crystalline structure of cellulose during solvent purification (e.g., temperature, reaction time, acidity and type of acid catalyst) was also examined. Acidity and acid catalyst type were found to contribute to crystalline structural changes of cellulose. The use of higher concentrations for acids (TFA, HCl) has led to a decrease in crystallite size and crystallinity index. However, lower concentrations of TFA have a positive impact on the crystallinity index of the treated cotton cellulose. The crystallinity index of the residual cellulose has shown a slight increase with the increase in temperature, while the crystallite size has indicated a successive decrease. The reaction time has offered, in general, better chances for enhancement of the crystallinity index of the cellulose.