An Environmentally Friendly Solvent for Cellulose Acetate Production: Ethyl Lactate

Abstract

The aim of this study was to investigate the possibilities of using biodegradable ethyl lactate instead of acetic acid, the most preferred solvent in industrial production, during cellulose acetate synthesis under certain conditions. In the study, dissolving pulp fibres, which were activated with water and acetic acid respectively, were dispersed in ethyl lactate after pressing and then subjected to acetylation reaction with acetic anhydride catalysed by sulfuric acid. The properties of acetylated cellulose were determined using X-Ray diffraction analysis, Fourier-transform infrared spectroscopy, Differential Scanning Calorimetry and other chemical analysis methods (viscosity, the percentage of bounded acid, chemical resistance). It was determined that it was possible to produce cellulose acetate with a DS value of 2.79 in ethyl lactate at 40°C using dissolving pulp. Fourier-transform infrared spectroscopy studies revealed a characteristic band broadening in the 1739 cm-1 region, indicating the presence of acetyl groups. The results of X-ray diffraction analyses also showed that the crystalline structure of cellulose was completely dispersed and band broadenings on diffractograms occurred. However, the calculation made on X-ray diffractograms also provided interesting findings in terms of crystallite sizes. It was observed that the crystallite sizes of the acetates were higher compared to the dissolving pulp. It was determined that the high crystallinity of the samples posed a problem in terms of processing properties such as dissolution. Among the solvents used, only Dimethylsulfoxide was found to have sufficient dissolving power.