Physico-Mechanical Properties of Films of Chitosan, Carboxymethyl Chitosan, and Their Blends

摘要

Transparent films of chitosan (CH), carboxymethyl chitosan (CMCH), and their blends were prepared using water or acetic acid as solvent and glycerol as plasti-cizer. Scanning electron microscopy micrographs of cross-section of the films indicated a multilayer structure for CH film and a compact and continuous one for CMCH film. In both solvent systems, increasing of concentration of plasti-cizer resulted in decreasing of tensile strength (TS) and increasing of elongation at break (% ε_b) of CMCH films. Moreover, CMCH films exhibited water vapor and oxygen barrier properties in the range of the values accepted for food packaging films (0.59-0.89 × 10~(14) kg/s m Pa and 0.8-3.1 × 10~(-3) ccO_2/m day atm). Although the barrier properties of CMCH films were comparable with that of CH films, CH film had significantly higher TS and % ε_b. Blending of CMCH with CH (75 and 25 %, respectively) significantly enhanced the TS and % ε_b of the obtained film compared to CMCH films (2.1 and 1.7 times, respectively). The water vapor and oxygen permeabilities (1.25 × 10~(14) kg/s m Pa and 3.4 × 10~(-3) ccO_2/m day atm, respectively) were still comparable with films of CH and CMCH.