Effects of heat treatment on some macroscopic and physical properties of Scots pine sapwood and heartwood

Abstract

Impact of heat treatment (ThermoWood) on the macro structure and physical properties of Scots pine sapwood and heartwood were studied by visual examinations, using the following relevant standard test methods: ASTM D2244 and TS 2472, respectively. In the study, two processes-Thermo-S (190 V) and Thermo-D (212V)-were employed for heat treatment.To compare the effect of different types of heat treatment, kiln dried wood samples were used for reference. Macroscopic investigation showed that superficial cracks occurred in all samples, and as the temperature increased, the severity and number of cracks increased. In the Thermo-D process, internal cracks and cupping were seen only in heartwood samples. Physical examination showed that as the temperature increased, color of the samples darkened, the density of the samples decreased, dimensional stability was enhanced.The Anti Swelling-Efficiency (ASE) in the Thermo-S and Thermo-D processes evaluated in sapwood samples was 17.04% and 24,77%, respectively; however, values in the heartwood samples were 11.97% and 3045%, respectively. The highest reduction ratio of air dried density was 14.04% in the thermo-D process applied to the heartwood samples. Thus, it can be concluded that this reduction due to the increased temperature is related to the formation of internal cracks.