Valorization of Grape Stalk Rachis for Particleboard Manufacturing: Chemical Characterization and Performance Assessment for Sustainable Interior Panel Applications

The wine industry generates large volumes of grape stalk residues that remain largely underutilized and are frequently disposed of by open-field burning, contributing to greenhouse gas emissions and the loss of biomass valorization opportunities. This study aims to evaluate the feasibility of producing single-layer particleboards from grape stalk particles (Vitis vinifera L.) bonded with a urea–formaldehyde resin, with a focus on their suitability for interior non-structural applications. Particleboards were manufactured at three target densities (550, 650, and 750 kg/m3) and assessed mainly for their physical and mechanical performance in relation to the requirements of EN 312. Internal bond strength showed a clear dependence on board density: panels produced at 650 and 750 kg/m3 met the minimum threshold for P2-type particleboards, whereas those produced at 550 kg/m3 did not comply with the standard. Thickness swelling decreased with increasing density, with only the highest-density boards fulfilling the reference criterion. Overall, the results indicate that grape stalk residues can be effectively converted into particleboards with adequate mechanical performance when manufactured at densities of at least 650 kg/m3. The study highlights the potential of this agro-industrial residue as a low-impact raw material for particleboard production, supporting circular bioeconomy strategies and development in wine-producing regions.