Enhancing the Mechanical Properties of Wood Plastic Composites with Banana Pseudo-stem Biochar as a Sustainable Filler

Abstract

Malaysia faces significant waste management challenges, generating over 30,000 tons of waste daily with a recycling rate of approximately 5%. In this context, transforming plastic and agricultural residues into sustainable construction materials offers a promising solution. This study investigates the incorporation of banana pseudo-stem (BPS) biochar into wood-plastic composites (WPC) to form wood-plastic biochar composites (WPBC). The composites were formulated using recycled high-density polyethylene (rHDPE), Pinus radiata pinewood sawdust flour, vinyltrimethoxy silane as a coupling agent, and BPS biochar filler produced through slow pyrolysis at 450°C. Biochar loadings of 0, 6, 12, 18, 24, and 30 wt.% were studied. The composites were processed via extrusion and hot-press moulding, and compressive strength testing was performed according to ASTM D3501-05a. Results show that WPBC exhibited higher compressive strength compared to conventional WPCs, with optimum performance at 18–24 wt.% biochar. WPBC 24 achieved 37.2 MPa compared to 30.8 MPa for WPC, representing a 20% improvement. However, excessive biochar (30 wt.%) reduced strength due to brittleness. The study demonstrates that banana pseudo-stem biochar is an effective, low-cost, and sustainable filler that enhances the mechanical properties of WPCs while contributing to waste valorisation. WPBC offers potential as an eco-friendly structural panel material for the construction industry.