Byantara Darsan Purusatama, Sena Maulana, Jong Ho Kim, Nam Hun Kim, Apri Heri Iswanto, Muhammad Adly Rahandi Lubis
The adhesion performance of waste cooking oil (WCO)–based polyurethane adhesives (Bio-PUA) in plywood was investigated. The WCO-based polyol was formulated at four different formulations of WCO and polyol, namely 1:4, 2:3, 3:2, and 4:1. The bond-line characteristics were analyzed using digital microscopy and Raman spectroscopy. At the same time, the physical and mechanical properties of the plywood were assessed in accordance with JAS No. 233:2003 standards. The fracture lines were filled with adhesive, and this was more pronounced in Bio-PUA with a low WCO content. Bubbles were observed in the bond line of untreated Bio-PUA, and the vessels in all samples were partially filled with adhesive. A strong peak in the Raman spectra at 1610 cm−1 confirmed effective urethane bond formation within both the bond line and the vessels. Quantitatively, Bio-PUA with lower WCO content achieved thicker bond lines but did not facilitate deep adhesive penetration. Adhesive distribution has a significant influence on plywood density and mechanical performance. Increased bond-line thickness improved panel density, while excessive penetration may reduce density without enhancing strength. Tensile shear strength in untreated Bio-PUA correlated strongly with both thickness (positive) and penetration depth (negative), whereas heat-treated Bio-PUA showed more consistent performance with no significant correlations. © 2025 Taylor & Francis Group, LLC.
Research Center for Biomass and Bioproducts, National Research and Innovation Agency, South Tangerang, Indonesia; Department of Forestry Engineering, Institut Teknologi Sumatera (ITERA), South Lampung, Lampung, Indonesia; Department of Forest Biomaterials Engineering, Kangwon National University, Chuncheon, South Korea; Department of Forest Products, Faculty of Forestry, Universitas Sumatera Utara, Medan, Indonesia