Performance of Particleboard Made of Agroforestry Residues Bonded with Thermosetting Adhesive Derived from Waste Styrofoam

Abstract

This paper investigated the upcycling process of thermoplastic waste polystyrene (WPS) into thermosetting particleboard adhesive using two cross-linkers, namely methylene diphenyl diisocyanate (MDI) and maleic anhydride (MA). The WPS was dissolved in an organic co-solvent. The weight ratio of WPS/co-solvent was 1:9, and 10% of cross-linkers based on the WPS solids content were added subsequently at 60 °C under continuous stirring for 30 min. The adhesive properties, cohesion strength, and thermo-mechanical properties of WPS-based adhesives were examined to investigate the change of thermoplastic WPS to thermosetting adhesives. The bonding strength of WPS-based adhesives was evaluated in particleboard made of sengon (Falcataria moluccana (Miq.) Barneby & J.W. Grimes) wood and rice straw particles at different weight ratios according to the Japanese Industrial Standard (JIS) A 5908:2003. Rheology and Dynamic Mechanical Analysis revealed that modification with MDI and MA resulted in thermosetting properties in WPS-based adhesives by increasing the viscosity at a temperature above 72.7 °C and reaching the maximum storage modulus above 90.8 °C. WPS modified with MDI had a lower activation energy (Ea) value (83.4 kJ/mole) compared to the WPS modified with MA (150.8 kJ/mole), indicating the cross-linking with MDI was much faster compared with MA. Particleboard fabricated from 100% sengon wood particles bonded with WPS modified with MDI fulfilled the minimum requirement of JIS A 5908:2003 for interior applications.

Surface Roughness, Dynamic Wettability, and Interphase of Modified Melamine Formaldehyde-Based Adhesives on Jabon Wood

“…In contrast, the loss modulus of the wood–MF-0 adhesive was higher than that of wood–MF-1. The loss modulus of a wood–adhesive interphase pertains to the capacity of the interface between the wood and the adhesive to release energy when subjected to dynamic loading conditions [ 57 ]. Various factors, such as adhesive formulation, curing conditions, wood surface preparation, and unique wood features, affect the loss modulus of the wood–adhesive interphase.…”

“…This result is in line with the stiffness of wood-MF resin as a function of temperature (Figure 8b). Wood-MF-0 reached a maximum stiffness of 957 N/m at 123.0 • C, while the wood-MF-1 had a maximum stiffness of 2734 N/m at 110.5 • C. The stiffness of wood adhesives is crucial in determining the overall structural integrity and performance of bonded wood products [57]. This study showed that MF-1 had a greater stiffness and could produce a better performance in its bonded wood products compared to MF-0.…”