Outdoor performance of wood-plastic composites enhanced with nano graphene-epoxy coating

This study evaluated the outdoor performance of wood-plastic composites (WPCs) coated with epoxy-based coatings containing graphene nanoplatelets (GNPs) after 336 h of artificial weathering. Results indicated that color change is inevitable. The GNPs covered the surface of the WPCs and restrained the UV degradation. The lowest color changes were observed in the 0.5% GNPs coating. Contrastingly, crack formations were noted on the coating surface without GNPs. Scanning electron microscopy analysis clearly revealed the splitting of the coating due to UV exposure. As the GNPs ratios increased, the crack formation decreased. Similarly, the macroscopic investigation showed that the surface roughness of the coatings decreased with increasing GNPs. Color stabilization also improved with the increased GNPs. Meanwhile, color changes occurred more rapidly in WPCs coated with pure epoxy. Epoxy-based coatings containing GNPs effectively stabilized the surface color. Additionally, GNPs restricted mechanical losses, with a reduction of only 3.68% for the epoxy coating containing 1% GNPs, compared to a 19% loss in pure epoxy-coated WPCs. In conclusion, coatings containing GNPs considerably enhanced the weathering performance of WPCs.