4.4. Chitosan/PLA blends
Chitosan is a natural polymer, non-toxic, edible, biodegradable, derived by deacetylation of chitin and is the second most abundant biopolymer in nature after cellulose. Chitosan has been used in edible coatings or films to extend the shelf life of foodstuffs, e.g. fruit, meat, and fish and seafood. However, its high sensitivity to moisture limits its applications for packaging. One strategy to overcome this drawback is the blending of chitosan with moisture-resistant polymers, while maintaining the overall biodegradability of the products. Suyatma et al. 197] reported on biodegradable film blends of chitosan with PLA by solution mixing and film casting. The main goal of these blends was to improve the water vapor barrier of chitosan by blending it with a hydrophobic biodegradable polymer from renewable resources. The incorporation of PLA with chitosan improved the water barrier properties and decreased the water sensitivity of chitosan film. However, the tensile strength and elastic modulus of chitosan decreased with the addition of PLA. Mechanical and thermal properties revealed that chitosan and PLA blends are incompatible, consistent with the results of FTIR analysis that showed the absence of specific inter- action between chitosan and PLA. 4.5 PHB/chitosan and PHB/chitin blends