Preparation and characterisation of methylated hemicelluloses from wheat straw

Wheat straw hemicellulose ether was prepared by methylation with methyl iodide using sodium hydride as a catalyst reacted in dimethyl sulphoxide. The degree of substitution (DS) was determined by elemental analysis. According to the elemental analysis data, the DS-value can be calculated; it was 1.7. The structure of the methylated hemicellulose formed was characterised by nuclear magnetic resonance (NMR) and Fourier transform infrared (Fr-IR) spectroscopy. The thermal properties of the prepared ether were studied by simultaneous thermal analyser (STA 625). Differential scanning calorimetry (DSC) was also used to determine the thermal profile of the material degradation. It was found that the thermal stability of wheat straw hemicellulose ether increased by methylation. (C) 2001 Elsevier Science Ltd. All rights reserved.