Development of lightweight human prosthetic vinyl based composite material using porous biocarbon, low density luffa fibre and recycled waste polyethylene terephthalate (PET) foam

Reinforcement using bio-waste and recycled materials is increasingly favoured in composite development due to their enhanced sustainability and promising performance when compared to synthetic alternatives. In this study, recycled PET foam was utilized as the core material to control the weight gain in the composite. The composites were fabricated with chopped luffa fiber, recycled PET foam, and walnut shell-derived porous biocarbon, and evaluated for tensile, flexural, impact, hardness, water absorption, and flammability properties, following relevant American Society for Testing and materials (ASTM) standards. Among the specimens, the composite PRC1 (with 3 vol.% filler) exhibited the highest tensile strength (120 MPa), flexural strength (143 MPa), and impact resistance (5.0 J), indicating optimal reinforcement at this filler level. In contrast, PRC2 (5 vol.% filler) achieved the highest hardness and exhibited an excellent flame resistance rate of 6.53 mm/min. The control sample P (100 vol.% vinyl ester) showed the lowest water absorption at 3.2%, reflecting the hydrophobic nature of the matrix. Additionally, scanning electron microscopy (SEM) was performed to examine the fracture surfaces post mechanical testing, providing insights into failure mechanisms and fiber–matrix interactions. Based on the performance characteristics, these composites show strong potential for use in applications such as lower limb prosthetic sockets, upper limb prosthetic frames and covers, cranial and facial prosthetics, and adaptive sports prosthetics.