Influence of the compatibilizer on plywood bonded with an adhesive film made of recycled expanded polystyrene foam

In this study, the polystyrene adhesive film was developed using expanded polystyrene (EPS) foam waste dissolved in D-limonene, which is extracted from orange peel. The three-layer plywood was made using polystyrene film as the adhesive between the layers. Styrene maleic anhydride (SMA) as a coupling agent (CA) was used in different percentages and in two different ways to improve the adhesion of wood to the polymer. The best performance was obtained by incorporating SMA compatibilizer into the polystyrene solution to form polystyrene adhesive film. Increasing the amount of compatibilizer up to 10% in the adhesive film structure, resulted in approximately 30% higher shear strength, 34% higher tensile strength, 11.7% higher bending strength and 19.5% modulus of elasticity than in the corresponding samples without compatibilizer. Spraying the compatibilizer onto the surface of the wood veneers did not significantly improve the mechanical properties of the plywood, but it did have a positive effect on reducing the TS after 24 and 168 h of water immersion. The results of the MFI and molecular weight indicators (Mw and Mn) show that the incorporation of SMA into the adhesive film reduces the viscosity of the polystyrene matrix and thus improves the flowability of the polymer. In general, the adhesive films prepared with EPS foam waste dissolved in limonene and 5% SMA as a compatibilizer worked well as an adhesive to produce interior plywood according to the requirements of EN 314-2.