Preparation structure and properties of thermoplastic chitosan-starch composites

The escalating environmental concerns and depletion of finite fossil resources have made the development of novel degradable materials paramount. Chitosan, a deacetylated derivative of chitin, is a versatile biopolymer employed in various fields because of its biodegradability and film-forming ability. However, its poor mechanics limit its use. However, blending chitosan with other polymers produces suitable composites. In this study, thermoplastic chitosan/starch composites are prepared via banbury mixing using hydrochloric acid aqueous solution as the plasticizer. Additionally, the impact of varying levels of starch content and different molecular weights of chitosan on the structural composition and overall properties exhibited by the composites under study is investigated. The hydrogen-bonding interactions between chitosan and starch are verified by Fourier transform infrared spectroscopy. The morphological analyses of the chitosan/starch composites show a dispersion of starch particles within the chitosan matrix. Furthermore, the addition of starch has a negligible effect on their crystallinity but reduces their hydrophilicity. Compared to pure chitosan, an increase in the starch content decreases the tensile strength and increases the thermal stability of the composites, whereas their elongation at break first increases and then starts decreasing. Furthermore, an increase in the chitosan molecular weight increases their elongation at break. Thus, this study proposes a novel method for preparing thermoplastic chitosan/starch composites.