Acetylation of wheat straw hemicellulose B in a new non-aqueous swelling system |
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Authors: | J M Fang R C Sun J Tomkinson P Fowler |
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Institution: | The BioComposites Centre, University of Wales, Bangor, Gwynedd LL57 2UW, UK |
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Abstract: | The acetylation of wheat straw hemicellulose B was carried out in a homogeneous N,N-dimethylformamide and lithium chloride system with acetic anhydride using 4-dimethylaminopyridine as a catalyst. The degree of substitution of hemicellulose B acetates ranged between 0.59 and 1.25 as a function of experimental conditions. Under an optimum condition (85°C, 60 h), approximately 75% of the free hydroxyl groups in native hemicellulose B were acetylated. The molecular weight measurements (31,890–34,090 g mol?1) showed a controllable degradation of hemicellulose B chains during the reactions at temperature 60–85°C and duration of 2–60 h. It was found that the thermal stability of the products was increased by chemical modification. |
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Keywords: | Wheat straw Hemicellulose B acetate Homogeneous system Acetylation |
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