3.4. DSC analysis
DSC thermograms of chitosan and EHCs are shown in
Fig. 4. The spectra of chitosan shows a broad endothermic
peak around 103.9 C and sharp exothermic peak at
322.6 C. The former endothermic peak may be due to
the water vapor that the chitosan contains. While the latter
may be attributed to the decomposition of chitosan. The
endothermic peak of EHCs around 96.31 C may be due
to the loss of water and moisture content in the polysaccharide.
The exothermic peak at 229.69 C corresponds to its
thermal decomposition. The results indicated that the
structure of chitosan chains has been changed due to the
introduction of a large quantity of –OH and –NH2 and
the reduced ability of crystalization.