Physicochemical and Fire-resistant Properties of Optimized Nipa Palm-based Flame-retardant Composite

Abstract

Increasing demand for bio-based fire-retardant products requires abundant agricultural waste. The nipa palm, found in Malaysian estuaries, especially Sarawak, is an important, underutilized lignocellulosic resource. This study investigates the physicochemical and fire-retardant properties of a composite made from nipa palm biomass. Polyvinyl alcohol (PVOH) was crosslinked with citric acid and reinforced with calcium carbonate to produce the composite with the nipa particles. Microstructural and compositional analyses were performed utilizing scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX), while mechanical characteristics, dimensional stability, and fire performance were rigorously investigated. The improved composite met JIS A 5908 (2003) structural particleboard standards with a modulus of rupture of 14.8 MPa, an internal bond strength of 3.88 MPa, and a modulus of elasticity of 2.9 GPa. The SEM images showed a compact, uniform cross-section with minimal voids and strong fiber-matrix adhesion. The EDX demonstrated the consistent distribution of CaCO₃ within the composite matrix. Synergistic interactions between PVOH–citric acid crosslinking and mineral filler reinforcement increased flame resistance and char formation in the limiting oxygen index fire analysis. This research showed nipa palm biomass to be a sustainable feedstock for high-performance fire-retardant particleboards. The work offers insight into eco-friendly interior binder systems.