CHITOSANS FROM EUPHAUSIA-SUPERBA .2. CHARACTERIZATION OF SOLID-STATE STRUCTURE

Chitosans from Euphausia superba of different degrees of acetylation (42%, 28% and < 5%) were characterized by X-ray diffractometry, CP-MAS C-13-NMR and FTIR spectroscopy to study the influence of both the regeneration process and the degree of polymerization on chitosan structure. The X- ray powder patterns indicated a decrease of order with decreasing the degree of acetylation as well as after regeneration and acid treatments. Similarly, the CP-MAS C-13-NMR and FTIR spectra exhibited a general broadening of signals suggesting the occurrence of new conformations for chitosans after regeneration. Furthermore, samples treated with hydrochloric acid showed some structural modifications which accounted for their behaviour in solution as reported in the first part of this study.