Elastic modulus of the crystalline regions of chitin and chitosan

The elastic moduli El of the crystalline regions of α-chitin and chitosan in the direction parallel to the chain axis were measured by X-ray diffraction. The El values were 41 GPa for α-chitin, and 65 GPa for chitosan, respectively, at 20°C. The contracted skeletons of α-chitin and chitosan are the key factor for the low El values compared with that (138 GPa) of cellulose I. The El value of α-chitin was constant at 41 GPa both at −190°C and 150°C, which indicates that the molecular chain of α-chitin is stable against heat within the temperature and stress range studied.