Preparation and characterization of acetylated Eucommia ulmoides Oliver hemicelluloses

Acetylation of Eucommia ulmoides Oliver hemicelluloses with acetic anhydride using N-bromosuccinimide (NBS) as catalyst in a homogeneous N, N-dimethylformamide (DMF)/lithium chloride (LiCl) system was studied. The yield percentage varied from 72.1% to 87.5%, corresponding degree of substitution from 0.59 to 1.36. The total degree of substitution can be simply controlled by the reaction conditions such as reaction temperature and duration. Both yield and DS increased with increment in temperature from 60 to 90 degrees C and prolonging reaction time from 6 to 72 h. The results also showed that NBS can be used as a effective catalyst for acetylation of hemicelluloses. The modified products and natural hemicelluloses were comparatively studied by using FT-IR and thermal analysis. Thermal analysis of both the material and acetylated hemicelluloses indicated that the thermal stability of the hemicelluloses was increased by chemical modification.