Effects of thermo-hydro-mechanical treatments on various physical and mechanical properties of poplar (Populus) wood

Abstract

Poplar (Populus) wood was subjected in this work to thermo-hydro-mechanical treatment. The influence of the treatment parameters on the physical and mechanical properties were investigated. The wood samples were densified under three compression ratios (0%, 30%, and 50%), and thermally treated at three temperatures (180 °C, 200 °C, and 220 °C), at three thermal treatment durations (3 h, 4 h, and 5 h). The density, modulus of elasticity, modulus of rupture, radial hardness, and thickness swelling were measured. The results showed that the densities of the samples increased by 36.6% to 49.7%. As the compression rate increased, the temperature, duration, modulus of elasticity, modulus of rupture, and hardness increased. However, the dimensions of the densified samples were less stable. Compared to the densified samples, the maximum thickness swelling could be reduced by 74% (from 29.7% to 7.8%) when subjected to a thermal treatment at 220 °C for 3 h.

Two-step hot isostatic pressing densification achieved non-porous fully-densified wood with enhanced physical and mechanical properties

“…Although this is a positive effect, dimensional stability could be standardized by a detailed study of the thermal variable of the process without including an additional step. It has been reported that the thermal phase provides better dimensional stability to the densi ed wood 54 , but it also has signi cant adverse effects on the physical and mechanical properties of the wood due to the degradation of its chemical components 55 . Finally, it is important to mention that total immersion tests were also performed for 24 h, nevertheless, the results of these tests were not statistically conclusive and, so they were not included in the present work.…”