The effect of chitosan content on the crystallinity,thermal stability,and mechanical properties of bacterial cellulose—chitosan composites

Abstract

A bacterial cellulose—chitosan (BC—Chi) composite has been successfully prepared by immersing wet BC pellicle in chitosan acetic acid solution followed by freeze-drying. By changing chitosan concentration and immersion time, a foam-like structure is made with the chitosan content in the range of 12—45 per cent. Scanning electron microscope images show that chitosan molecules can penetrate into BC forming a multi-layer structure. This foam has a very well interconnected porous network structure. The X-ray diffraction patterns indicate that with the increase in chitosan content, the crystalline structure is not changed but the crystallinity index tends to decrease. The thermal degradation temperature increases from 263 to 366 °C with the chitosan content increasing from 12 to 45 per cent. The tensile test results show that the tensile strength and Young's modulus of BC—Chi composites tend to decrease with the increase in chitosan content but the value is much higher than that of pure chitosan. This improved elasticity of the BC—Chi composites is important for biomedical applications.