A green and sustainable three-layer bamboo particleboard from chopstick waste bonded with bio-based polyurethane composite for engineering applications

Abstract

This study presents the fabrication and performance evaluation of a sustainable three-layer bamboo particleboard (3LBP) designed for engineering applications. Chopstick waste bamboo (CWB) was used as a renewable raw material and bonded with a castor oil-based polyurethane (PU) adhesive at 12 wt% relative to the oven-dry mass of the bamboo particles. The 3LBP structure comprised fine CWB particles (50-mesh) in the face layers and coarse CWB particles (5-mesh) in the core, with varying layer ratios (1:1:1, 1:2:1, 1:3:1, 2:1:2, and 3:1:3). The influence of the layer structure on the physical, mechanical, thermal, and acoustic properties was systematically investigated. Increasing the proportion of fine particles in the surface layers enhanced dimensional stability and strength. The 3:1:3 configuration demonstrated the most balanced performance, achieving a modulus of rupture (MOR) of 62.93 MPa and a modulus of elasticity (MOE) of 18,908 MPa in static bending tests (EN 310), both surpassing the requirements of the EN 312 standard for P7-grade particleboard (heavy-duty load-bearing boards for use in humid conditions). Additionally, it exhibited favorable thermal conductivity (0.106 W/m·K) and sound absorption average (SAA) of 0.04. The 1:1:1 ratio offered superior thermal insulation (0.081 W/m·K) but limited acoustic response. With an internal bond (IB) of 0.55 MPa and surface soundness (SS) of 1.14 MPa, the optimized 3LBP formulation demonstrates strong potential for application in furniture panels, partition systems, and interior construction components, providing an eco-efficient and high-performance alternative to conventional engineered materials such as wood-based particleboard and medium-density fiberboard (MDF).