Recycled polyethylene terephthalate powder in particleboard production: Epoxy as a formaldehyde-free adhesive alternative

This study investigated the production of particleboards by incorporating recycled polyethylene terephthalate (PET) powder into Pinus spp. particles, using epoxy resin as an adhesive at 5% and 10% levels. The panels were manufactured and tested in accordance with ABNT NBR 14810-2 (2024) and further evaluated under EN 312 (2003) and ANSI A208.1 (2016) standards. The results demonstrated that both the increase in adhesive content and the incorporation of PET powder contributed to significant improvements. Compared with literature data on panels without PET, the addition of recycled PET reduced moisture content (MC), thickness swelling (TS), and water absorption (WA) by about 29% and promoted mechanical gains of up to 33% in modulus of elasticity (MOE), 31% in modulus of rupture (MOR), and 133% in internal bond strength (IB). Increasing epoxy from 5% to 10% further enhanced performance, with reductions of 46.3% in TS and 49% in WA after 24 h, and increments of 57.1% in MOR, 68% in MOE, and 104.3% in IB. Scanning electron microscopy confirmed improved encapsulation of wood and PET particles with 10% adhesive. These findings point to a viable circular-economy route by upcycling plastic waste and wood residues into higher-value particleboards while avoiding added formaldehyde.