Effect of thermal treatment on physical and mechanical properties of birch and pine wood

Abstract

No simple method has yet been found for satisfactory wood bio-resistance improvement regarding material performance in its end-use. An attempt to obtain material with proper strength and bio-durability by combined wood thermal modification and impregnation with a biocide is being researched. To select the most appropriate treatment conditions for the combined process, changes in wood physical and mechanical properties depending on the treatment temperature were investigated in the present study. For the investigation, in Latvia the most widespread woodsoftwood pine (Pinus sylvestris L.) and hardwood birch (Betula spp.) was used. Changes of wood mechanical and physical properties due to thermal modification were investigated and effect of treatment temperature and relative humidity on wood characteristics evaluated. It was found that, due to different degree of changes, no identical treatment conditions suit for birch and pine wood. Birch wood is considerably more sensitive to temperature and acceptable strength was maintained only for birch wood treated at 150 °C and for pine wood treated at 160 °C. Nevertheless at higher environmental humidity equilibrium moisture content and consequently radial and tangential swelling increased for all studied wood types, substantially smaller changes due to elevated humidity were detected for modified wood.

Changes in the physical and mechanical properties of Pinus taeda and Eucalyptus bosistoana wood modified by contact charring

“…A number of studies on thermal and charring treatments of wood showed decreases in wood densities due to chemical modifications in the wood (Metsä-Kortelainen et al 2006;Boonstra et al 2007;Gündüz et al 2008;Akyildiz et al 2009;Gunduz et al 2009;Won et al 2012;Percin et al 2016;Antons et al 2018;Kapidani et al 2019;Chotikhun et al 2020;Wang et al 2020;Esteves et al 2021;Gennari et al 2021;Ninane et al 2021;Šeda et al 2021;Taraborelli et al 2022). Hill et al (2021) showed that thermal treatments for heat-modified wood generally resulted in increased mass loss and decreased wood density due to chemical degradation and that weight loss after heat treatment was generally linked to a reduction in density associated with treatment conditions and wood species (Pfriem et al 2009).…”

Behavioral change in physical, anatomical, and mechanical characteristics of thermally treated Pinus roxburghii wood

“…The comparative decrease could be seen in untreated and thermally treated wood of pine, fir, and black pine wood species. Antons et al (2018) concluded that the temperature treatment of birch and pine wood resulted in the improvement of wood hydrophobicity. The findings of the present study are in line with above results obtained by different workers.…”

The potential of improving wood preservative penetration into glued wood products bonded with one-component polyurethane by discontinuous adhesive bondline design

“…The second concerns water plasticizing effects, which result in reduced mechanical strength of the adherents (Bowditch 1996). Regarding the second mechanism, it is known that the strength of both wood and 1C-PUR films decreases by increasing the moisture content (Kläusler et al 2013;Antons et al 2018). Overall, the shear tests clearly show that the adhesive application design has a significant effect on the bond strength of the glued wood specimens.…”