| Summary: | 碩士 === 國立成功大學 === 化學工程學系碩博士班 === 95 === In order to select an ideal chitosan species as a material for further chemical modification, the relationship between molecular weight and degree of deacetylation was investigated for chitosan through enzymatic degradation.
Through this study we use viscometry, GPC and DOSY for analyzing molecular weights and diffusion coefficients; XRD and 1H NMR to determine the crystalline index and degree of deacetylation, respectively. The results showed that the cellulase degradation was by endo-action, and degree of deacetylation did not change after degradation. The decrease of molecular weight led to transformation of crystal structure, but the chemical structures of residues were not modified. Within 12 hours, molecular weight of chitosan was decreased from 500 kDa to 50 kDa and PDI from 7.02 till 2.53, under 1000 µg/mL cellulase. Enzymatic degradation is a mild and specific method to get chitosan for more investigations and applications.
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