Mechanical properties of chitosan/bamboo charcoal composite films made with normal and surface oxidized charcoal

Chitosan/bamboo charcoal composite films were prepared by blending chitosan with either virgin bamboo charcoal or bamboo charcoal modified by nitric acid oxidation to provide more hydrophilic regions on the bamboo charcoal surface. Investigation of the physical properties of these composite films revealed that the tensile strength and Young’s modulus of the chitosan films were enhanced in a dose-dependent manner by the inclusion of modified bamboo charcoal at up to 1% (w/w), whilst the elongation at break was increased by inclusion of modified bamboo charcoal at up to 0.5% (w/w). In contrast, chitosan composites with virgin bamboo charcoal at up to 0.5% or 1.0% (w/w) showed no enhancement of the tensile strength or Young’s modulus, respectively, and both parameters were reduced with higher levels of virgin bamboo charcoal. Oil, and especially water, absorption of the composite films displayed a marked and dose-dependent increase compared to those of the pure chitosan film.