Effects of heat treatment and impregnation with zinc-oxide nanoparticles on physical, mechanical, and biological properties of beech wood

Effects of zinc-oxide nanoparticles on physical and mechanical properties, as well as biological resistance of untreated and heat-treated beech wood were investigated in this study. Test specimens were prepared from sapwood and impregnated with a 5,000-ppm nano-zinc-oxide (NZ) suspension with a size ranging from 10 to 80 nm at 2.5 bars of pressure and using the Rueping process for 20 min. Control (C) and nano-zinc-oxide-impregnated specimens after (NZA) and before (NZB) heat treatment were divided into four subgroups of unheated (C and CNZ), heated at 50, 145 and 185 °C. Heat treatment resulted in a significant decrease in mechanical strength at temperatures of 145 and 185 °C. Heat-treated specimens showed less dimensional instability and fungal degradation. Impregnation with nano-zinc resulted in a slight and significant increase in weight loss and biological resistance against Trametes versicolor. The results showed that the impregnation significantly decreased the water absorption of the specimens. Impregnation before heat treatment showed considerable effect on the properties of wood compared to that of untreated ones.