Abstract
The chemical structure of chitin from the exuvia of silkworm pupae after treatment with 1N HCl and 1N NaOH was examined by X-ray diffraction, 13C CP/MAS NMR and SEM. X-ray diffraction and 13C CP/MAS NMR proved that the silkworm chitin is of α-form and shows a high crystalline structure as well as the shrimp chitin, but it is slightly different from the shrimp chitin in the amorphous structure because it can be degraded by 6N HCl more easily. After treatment with HCl, crystallinity of the silkworm chitin increased from 64.51% to 81.30%, but that of the shrimp chitin increased from 69.82% to 73.50%. The yields decreased that the silkworm chitin is by 56%, while the shrimp chitin is by 33%. For the silkworm chitin, the lattice constant of crystalline was a, 4.73; b, 18.74; c, 9.76Å, based on the standard of α-chitin. Observations by SEM showed the micropores structure of silkworm chitin xerogel.
