Adhesion and Cohesion Performance of Polyurethane Made of Bio‐Polyol Derived from Modified Waste Cooking Oil for Exterior Grade Plywood

Abstract This study explored the feasibility of Waste Cooking Oil (WCO)‐based Bio‐Polyurethane (Bio‐PU) as an eco‐friendly alternative to petroleum‐derived polyols in plywood adhesives. The objective is to evaluate the impact of varied WCO concentrations and methylene diphenyl diisocyanate (MDI) levels on Bio‐PU and plywood performance. The Bio‐PU's characteristics, rheology, and functional groups are studied. Plywood made from three layers of 100 mm x 100 mm × 2 mm rubberwood ( Hevea brasiliensis ) veneer is bonded with Bio‐PU using a dual spread approach at 180 g.m −2 , hot pressed at 120 °C and 1 MPa for 4 min. The laboratory‐fabricated plywood is tested for physical, mechanical, and adhesive properties. Results showed that Bio‐PU exhibited unique adhesive characteristics, with excellent adhesive strength, despite a slight decrease with higher WCO concentrations. WCO insertion do not compromise delamination resistance. FTIR analysis confirmed successful polyurethane chain synthesis. This research highlighted the potential of WCO‐based Bio‐PU's as a sustainable, high‐performance plywood adhesive.