Innovative Biobased Composites from Oil Palm Trunk: Enhancing Mechanical and Flame-Retardant Properties through Optimized Additive Treatments

This study investigates the development of an oil palm trunk (OPT) high-performance flame-retardant composite derived from an inexpensive and sustainable biomass source, processed using sodium chloride (NaCl) as a low-cost flame retardant, polyvinyl alcohol (PVA) as an adhesive, and calcium carbonate (CaCO3) as an additive. The work aims to address the inherent flammability of OPT and to enhance its mechanical performance, dimensional stability, and fire resistance in an environmentally friendly and cost-effective manner. Results indicate that a 10% NaCl treatment optimally improves the performance of the composite, increasing bending strength (MOR) from 5.95 to 12.61 MPa and internal bonding strength (IB) from 2.05 to 4.18 MPa. Dimensional stability was significantly enhanced, thickness swelling (TS) and water absorption (WA) being reduced by 43.8% and 51.3%, respectively. Flame retardancy was significantly enhanced, achieving an Underwriters Laboratories (UL-94) V-0 rating and a limiting oxygen index (LOI) value of 33.57%. Higher NaCl concentrations exceeding 10% led to reduced mechanical performance and flame retardancy, likely due to disruption of matrix-fiber interactions or the formation of voids. Compared to halogenated or phosphorus type flame retardants, the NaCl had an advantageous cost, ecology and processing ease, along with the removal of toxic emissions. Synergistic effects of NaCl, PVA, and CaCO3 contributed to reduced water absorption, enhanced dimensional stability, and improved fire resistance, making this composite a viable green product for applications where flame retardation is required. This study provides new insights into the utilization of agricultural waste products to develop eco-friendly flame-retardant composite materials, contributing to environmental sustainability and the production of fire-safe engineered wood products.