Incorporating Glass Wool into Urea–Formaldehyde Resin: Improvements in Fire Resistance and Dimensional Stability of Particleboards

Abstract Strategies for incorporating waste materials into particleboard production represent a pursuit of sustainable, functional innovations capable of reducing environmental impacts and improving technological properties. This study investigated the incorporation of glass wool (GW) waste as a filler material in urea–formaldehyde (UF) resin and its influence on the physical and fire-retardant properties of particleboards. Panels with a nominal density of 700 kg m–3 were produced with different proportions of glass wool in the adhesive (T1:0%; T2:3.34%; T3:4.93%; T4:6.52%; T5:9.49%; T6:12.35%). Particleboards were produced in a hydraulic press at 160 °C with a compression force of 4.12 MPa and a pressing time of 10 min. The adhesive content was fixed at 12% in relation to the oven-dry weight of the initial raw materials (adhesive, wood particles, and glass wool). The panels were analyzed using X-ray densitometry, XRD, and FTIR. Statistical analysis included regression, analysis of variance, and the Scott-Knott test (p < 0.05). The results indicated that the addition of 3.39% GW to the adhesive improved the dimensional stability of the panels, while higher contents, above 9.49%, enhanced fire resistance. These findings highlight the potential of glass wool as a functional filler material in UF resin, supporting the development of safer and more sustainable particleboards.