Effect of Heat Treatment on Sorption Properties and Dimensional Stability of Wood

Abstract

This research was performed in order to determine how the heating process affects sorption properties and dimensional and shape stability of oak, lime and birch wood. By subjecting specimens to 3 hours heating at 130, 160, 190 and 220 ºC temperatures, a decrease in volume, density and mass was observed in proportion to the applied temperature. It was established that when oak wood specimens underwent heating at 220 ºC temperature, the decline of mass was 1.2 times higher than in the case of birch specimens. Both heated and unheated specimens underwent moistening in air at 25 ºC ±1 ºC temperature for 3 weeks with relative humidity being 85 % ±1 % and were soaked in water at room temperature for 4 hours. It was found that after applying high temperature heating, specimens absorbed smaller amounts of moisture. It was demonstrated that during the soaking process, the volume of unheated specimens was 3 times higher than in the case of specimens heated at 220 ºC temperature. The change in the volume of unheated oak was 1.27 times smaller than in the case of lime specimens and 1.16 times larger than in the case of birch specimens, which underwent heating at 220 ºC temperature. In addition, specimens that were exposed to heat had more stable measurements and shapes. It was noticed that the heating process caused significant changes in moisture and dimensional stability of specimens, when higher temperatures ranging from 190 ºC to 220 ºC were used.

DOI: http://dx.doi.org/10.5755/j01.ms.19.3.5239