Utilizing Agricultural Residue Peanut Husk in the Manufacture of Particleboard Using Foamable Polyurethane Adhesive

ABSTRACT This study developed a novel particleboard using agricultural residue peanut husk (PH) as a partial substitute for wood particles, glued with a formaldehyde‐free foamable polyurethane (PU) adhesive. Particleboards with a density of 640 kg/m ³ were produced with different proportions (0%, 20%, 40%) and morphologies (coarse and fine) of PH. The efficacy of foamable PU was compared with conventional polymeric diphenylmethane diisocyanate (pMDI). Foamable PU adhesive was synthesized by blending a polyol mixture with pMDI in order to create a three‐dimensional porous cross‐linked network system in the core layer. The prepared foamable PU adhesive had good stability at room temperature and high reactivity under heating conditions, indicating compatibility with the particleboard production process. Results showed that the particleboards made with coarse PH exhibited lower water affinity and higher mechanical properties than those with fine PH. There was a reduction in the mechanical properties with the increase in PH content. The use of foamable PU in the core layer significantly increased mechanical properties compared to pMDI bonded boards. It was confirmed that foamable PU formed a three‐dimensional porous network, enhancing bonding performance. Among the boards made with PH, the combination of 20% coarse PH and foamable PU adhesive resulted in the optimum properties, with the internal bonding strength higher than the reference board by 64%. The properties of boards made with coarse PH qualified the P2‐type particleboard requirements. This work demonstrates the viability of manufacturing particleboards with PH and foamable PU adhesives, offering a viable solution for agricultural waste utilization and reducing reliance on wood resources.