Effect of carboxymethylated chitosan and cellulose acetate on mechanical properties of PLA blends for biomedical applications

Chitin and chitosan are versatile and valuable biomaterials, with chitosan being abundantly found in the exoskeletons of crustaceans, insects, arthropods, and mollusks. The chemical extraction of chitin involves a series of steps, including deproteinization, demineralization, and decolorization. Chitosan is often combined with various polymeric materials, and polymer blending can enhance the mechanical properties of the resulting bioproduct. In this study, composites of poly(lactic acid) (PLA) with chitosan (Ch) and cellulose acetate (CA) were successfully fabricated using extrusion and injection molding techniques. The chitosan content, ranging from 0 to 7.5 wt. %, was incorporated into the PLA matrix to assess the impact of filler content on the mechanical and morphological properties of the composites. The chitosan powder was first alkalized and then etherified to obtain modified chitosan, specifically o-carboxymethylated chitosan (O-CMCh). The addition of chitosan led to a reduction in tensile strength, flexural strength, modulus of elasticity, and impact strength. However, the hardness of the composite improved with the inclusion of chitosan. The mesoporous structure of chitosan was characterized using nitrogen adsorption and desorption measurements. Morphological analysis revealed that the composite containing 3.75 wt. % chitosan exhibited significantly less fracture surface compared to other composites.