Physical and Mechanical Properties of Fir and Poplar Subjected to Tall Oil and Vacuum Heat Treatment

Abstract

Vacuum heat treatment creates an oxygen-free environment, thus positively effects the properties of wood compared to traditional heat treatment. Crude tall oil is a non-biocidal wood preservative, composed of resin and fatty acids and improves some properties of wood such as water uptake and decay resistance. In this study, tall oil dissolved in ethanol (10% and 20%) for impregnation of the fir and poplar samples according to full cell method, followed by subjected to vacuum-heat treatment at 180 ºC and 200 ºC for 1 and 2 h respectively. Water uptake and mechanical tests such as bending and compression strength of untreated and treated samples were investigated. Results showed that weight percent gain (WPG) was about two times higher for tall oil treatment at 20% than 10% of tall oil. Vacuum heat treatment showed similar trend with control samples in terms of water uptake, while combined treatment of tall oil and vacuum heating lowered the water uptake. The results of mechanical tests indicated that bending strength was not affected by tall oil treatment. Combination of tall oil and vacuum heat treatment improved the compression strength.