Reforming composite materials: Nano chitosan from Crassostrea madrasensis oyster shell waste as a green toughener for unsaturated polyester resin

This work demonstrates how shell waste can be upcycled into advanced polymer composites, thereby contributing to sustainable materials research. In this study, waste oyster shells were employed as a sustainable source for the preparation of nano chitosan, which was successfully used as a reinforcing agent in unsaturated polyester resin composites. We prepared chitin from Crassostrea madrasensis oyster shell wastes, and nano chitosan was obtained by deacetylating the synthesized chitin with sodium hydroxide under autoclave conditions. Characterization techniques such as FTIR, XRD, SEM, and TEM clearly indicate the formation of chitin and chitosan, and TEM observations evidently specify the formation of nano chitosan flakes. We developed a composite material by incorporating unsaturated polyester resin with nano chitosan. Mechanical properties of unsaturated polyester resin are found to be enhanced by the addition of nano chitosan. Utilising this biopolymer derivative to improve the properties of unsaturated polyester resin (UPR) composites presents an innovative avenue for environmentally sustainable product development. These nano chitosan–UPR composites could potentially find applications in environmentally friendly coatings, structural materials, and bio-based polymer reinforcement.