Mechanical Performance of PVC Paste Composites Reinforced with Brachirus orientalis Fish Shell

This study explores the effect of incorporating Brachirus orientalis shell powder as a natural filler on the mechanical and moisture absorption properties of polyvinyl chloride (PVC) paste composites. Composites were formulated with varying filler loadings (1 wt.%, 2 wt.%, and 3 wt.%) and evaluated through tensile testing and water absorption analysis. The results showed that low filler concentrations (1–2 wt.%) maintained tensile strength and ductility close to those of neat PVC, indicating good filler dispersion and interfacial bonding. However, at 3 wt.% filler content, a reduction in tensile strength and Young’s modulus was observed, likely due to agglomeration and microstructural defects. Despite this, engineering and true tensile strains increased with filler loading, reflecting improved toughness and energy dissipation. Furthermore, water absorption decreased with increasing filler content, demonstrating enhanced resistance to moisture ingress due to the barrier effect of the shell particles. These findings support the potential of B. orientalis shell powder as an eco-friendly reinforcement for improving the toughness and environmental durability of PVC composites.