Innovative Thermoplastics Composites Made from Recycled Poly(Propylene) Reinforced with Coconut Coir Fibers

This study aims to evaluate the properties of poly(propylene) or PP composite reinforced with coconut coir fibers, and how these vary with fiber length and composition ratio. This innovative thermoplastic composite material was manufactured using a low-tech process from only PP, coconut coir fibers, and xylene (dissolution agent). Therefore, this process is widely accessible whilst both reusing/recycling waste plastic and making use of waste fiber material to produce a useful material that can fulfill demand for wood products, which has many environmental benefits. In this research, the coconut coir fibers are used as reinforcement, as well as the filler of the composite. Nine variations in composite material were produced from three length categories of fibers (2-5 mm, 10-20 mm, and 30-40 mm) and three composition ratios (60:40, 70:30, and 80:20) of predominant plastics of PP and fibers. Physical properties of the respective composite, such as density, moisture content, and thickness swelling, were fulfilled to the Japanese Industrial Standard (JIS) for particleboard. Mechanical properties of the composites showed that both modulus of elasticity (MoE) and modulus of rupture (MoR) decreased as the length of the fibers used increased. Conversely, an increase in the proportion of PP resulted in a stronger composite. However, statistically, the interaction between the amount of PP and the length of coir fibers within the biocomposite did not influence their quality. These results demonstrate that a low-cost process for manufacturing composite from waste materials can meet most industry standards and indicate that further refinement of the process, building on these findings, could achieve an innovative thermoplastic composite with widespread structural applications whilst delivering environmental benefits.