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Chitin was isolated from the residue of enzymatically hydrolyzed crab, Portunus trituberculatus, and further deacetylated by alkaline boiling to make chitosan. The physical properties of chitosan solution and its film forming properties were examined. The functional characteristics of chitosan film were compared to those of cellophane, polyvinyl chloride (PVC) and polyethylene (PE) films. The proximate chemical composition. of chitin obtained from crab residue was 6.95% nitrogen, 0.3% crude ash and 4.57% moisture and the product yield was 12.8% based on a dry material basis. The degree of deacetylation of chitosan was 79∼92% and 70∼86%o as determined by IR spectroscopy, and 70∼86% as determined by colloid titration method each respectively. The chitosan at 1% acetic acid solution showed distinct pseudoplastic flow behavior. The flow behavior index and consistency index were 0.8886, 0.2084 MPa·s^n for 0.4% solution and 0.8498, 0.6190 MPa·s^n for 0.8% solution, respectively. The chitosan film had the highest tensile strength (888 kg/㎠) and water permeability (100 g/㎡· 24 hrs) among the tested films, but relatively low elongation property (49%). It showed the similar tear strength (90 kg/㎝) and light permeability (87.7%) to other films tested in spite of the relatively high haze value (12.5%). As the thickness of chitosan film increased from 0.025 to 0.050 mm, the tensile strength of film decreased distictively, and the degree of elongation, tear strenth, and water permeability of film also decreased slightly. Whereas the light permeability of film did not change and the haziness of film slightly increased by the increase of film thickness.
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