Effect of press conditions on physical and mechanical properties of hydro thermo- mechanical treated poplar wood

The aim of current research was to investigate the effect of hydro thermo-mechanical treatment and also press conditions on the physical and mechanical properties of poplar wood (Populus deltoides). The wood blocks were initially treated hydrothermally at temperatures of 100°C for holding time of 0, 60, 120 minutes. Afterwards, the densification process was carried out under a hot press at two phases 1- contact and 2- compression press, for temperature of 160, 180 and 200°C for 60 and 90 minutes. The wood compression set was adjusted for 40 percent based on the thickness (radial direction) of the blocks. The samples were physically and mechanically tested as density, springback after press, water absorption, thickness swelling, bending strength and modulus of elasticity. Afterward, the results were analyzed based on a complete randomized design (CRD) under a factorial experiment. Results revealed that physical and mechanical properties of samples were enhanced due to the combined hydro thermo-mechanical treatment. Results revealed that this process causes reduction of springback, water absorption and thickness (radial direction) swelling and also improvement of mechanical properties such as bending strength and modulus of elasticity.