The role of olive leaf extract and nanoparticles incorporation in polyacrylate coating structure on surface properties of heat treated wood during natural weathering

Wood coating with clear coats such as polyacrylate have a short service life since solar radiations pass through the coat and cause subsequent discoloration of wood surface. These phenomena can be decreased by using suitable UV absorbants in the coats. Therefore, in this research, olive leaf extract in combination with nano-particles of titanium dioxide (TiO2) and zinc oxide (ZnO) were added to the polyacrylate coat as the substrate to study the possible effects of different formulated coats on surface properties of the thermally modified wood after exposure to the natural weathering for a long period. The surface properties of the coated wood such as color change, surface roughness and wettability of the coated wood were studied during the weathering period. The microscopy was carried out on the coated wood to evaluate any morphological changes of wood surface as well as any mold growth. The results showed less color changes in the coated thermally modified wood. Also, surface roughness increased due to the weathering in all coats. However, roughness increased in all samples including control and treated ones, showing the highest roughness in uncoated samples. The result of contact angle showed that the polyacrylate coated samples kept their low wettability during the weathering periods. However, the wettability was increased in the control samples. It could also be concluded that olive leaf extract caused less mold growth and less color changes due to its anti-oxidant and bioresistance properties.