R. Sun, J. Fang, J. Tomkinson
Feb 1, 2000
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Journal
Polymer Degradation and Stability
Abstract
Abstract Stearoylated hemicelluloses with degrees of substitution 0.20–1.71 were prepared by a rapid reaction of wheat straw hemicelluloses with stearoyl chloride using 4-dimethylaminopyridine as catalyst and triethylamine as acid acceptor in a homogeneous N,N-dimethylformamide and lithium chloride system. Under optimum conditions approximately 92% of the free hydroxyl groups in native hemicelluloses were stearoylated in 30 min at 75°C. Molecular weight measurements showed only minimal degradation (⩽8%) of hemicellulosic chains during the rapid reactions at 75°C for 10–35 min, while a noticeable degradation (∼20%) of the stearoylated hemicelluloses was observed during the reaction at 85°C. Differential thermal analysis studies revealed an increase of the thermal stability of the stearoylated hemicelluloses.