Study on the influence of pretreatment and chain length of substituents on cellulose mixed esters

In this work, homogeneous esterification of the cellulose mixed esters was accomplished with water-activated alpha-cellulose, various saturated fatty acids, and acetic anhydride in lithium chloride/N,N-dimethylacetamide (LiCl/DMAc) medium to study the influence of activation and fatty acyl chain length on the cellulose mixed esters (CME). alpha-Cellulose was activated for 2 h at 50 A degrees C in deionized water prior to esterification. CME was obtained after esterification for 5 h at 120 A degrees C. The purified products were characterized in various ways. The morphology, structure, total degree of substitution, crystallization characteristics, thermal properties, contact angle, and film properties of CME were examined by FE-SEM, H-1 NMR, FTIR, XRD, DMA, TGA, and CAA. These analyses revealed that the water activation pretreatment of alpha-cellulose was the critical factor affecting the esterification efficiency which is related to the overall properties of the cellulose esters. It is also confirmed that the glass transition behavior of the cellulose esters changes depending on the chain length of the substituents.