Sustainable composites derived from functionalized vegetable oil reinforced with waste fish scales

Fish scales (FS), a major byproduct of the fish processing industry, are frequently discarded into the environment, affecting landfills and posing a threat to aquatic ecosystems. The present study aimed to minimize this waste by transforming it into value-added composite materials. In this study, biocomposites were fabricated using waste fish scales as the reinforcing filler, modified soybean oil (MAESO resin) as the matrix, and itaconic acid-glycidyl methacrylate adduct as the reactive diluent. The chemical structures of the resin and diluent were characterized using Fourier Transform Infrared Spectroscopy (FTIR) and Nuclear Magnetic Resonance (NMR) analyses. Composites with resin-to-filler ratios of 50:50, 60:40, and 70:30 were fabricated and comparatively evaluated. The results demonstrated that composite performance is strongly dependent on composition. The 60:40 composition exhibited a balanced combination of properties, with a tensile strength of 3.59 MPa, elongation at break (%) of 13.34 and shore D value of 72 indicating improved interfacial compatibility and surface characteristics. In contrast, the 50:50 composite showed the highest flexural strength (9.81 MPa), impact strength (47.31 J/m), attributed to increased filler content enhancing energy absorption capacity. However, excessive filler loading led to reduced dispersion and interfacial bonding as observed in SEM analysis. Thermogravimetric analysis further revealed increased char residue (48%) due to the presence of hydroxyapatite, contributing to improved thermal behavior. Overall, this study demonstrates the sustainable approach of converting fish scale waste into value added composite materials, highlighting the importance of composite optimization in tailoring specific properties.