Coating material u
Coating material used in this research
-Chitosan
Chitosan is a well known derivative of chitin, the major difference being the degree of deacetylation (DAC), which is the same as the relative amount of free amine .DAC refers to the relative amount of acetyl groups removed from the molecule, expressed as a percentage. Chitosan is obtained when chitin is subjected to strong caustic soda and heat which removes the N-acetyl group. (119) The production of Chitosan is currently based on crab and shrimp shells discarded by the canning industries. (120) The production of Chitosan from crustacean shells obtained, as a food industry waste is economically feasible, especially if it includes the recovery of carotenoids. (121) Chitosan derivatives are easily obtained under mild conditions and can be considered as substituted glucans.(122) Recently, the gel forms ability of Chitosan in N-methyl morpholine N-oxide .(123)Chitosan molecular weight distributions have obtain using HPLC .(124)The weight average molecular weight (Mw) of Chitosan has been determined by light scattering .(125) Chitosan is capable of undergoing many chemical modifications because it is an amino polysaccharide. The amino group (-NH2) is a useful functional group to alter chemically to produce new polymers. (126)Chitosan degrade before melting, which is typical for polysaccharides with extensive hydrogen bonding .(127) Chitosan is insoluble in water but it is soluble without degradation in weak acids such as 5% formic and acetic acids, and it is thermally stable up to 150ºC .(128)Chitosan is non-toxic and easily bio-absorbable .(129)Moreover ,chitosan has antacid and antinuclear activities which prevent or weaken drug irritation in the stomach .(130) Also ,chitosan matrix formulations appear to float and gradually swell in an acid medium. (131) Besides Chitosan is the only natural cationic gum that becomes viscous on being neutralized with acid .(132) Chitosan used in creames ,lotions ,permanent waving ,nail lacqueres, artificial skin , also Chitosan used as coating material and parallel linking agent in fabric used in medical textiles specially fabrics used in heart prostheses .(133)
