Effect of unilateral surface compression technique and heat treatment on industrial application performance of poplar

Abstract

The utilization of unilateral surface compression technique offers significant advantages such as reduced volume loss of wood and energy consumption, making it highly promising for widespread applications. This work focused on fast-growing poplar (Ctrl) as research subject. The unilateral surface compression technique was employed to prepare compressed wood (USW), while superheated steam was utilized to suppress rebound effects (resulting in the formation of US＆HW). The results showed that the combination of densification and heat treatment technology significantly enhanced the application performance of wood. Compared to Ctrl, the densified area exhibited a significant reduction in the volume of cell cavities, with a stepped distribution evident on the VDP. Furthermore, heat treatment resulted in a decrease in the relative amount of hydroxyl in the wood, as well as a slight increase in crystallinity. This effectively reduced deformation in dense wood, resulting in a 20.02% reduction in its recovery rate, without causing excessive damage to the VDP. Additionally, Heat treatment resulted in a darker wood color, reduced glossiness, increased roughness, and further increase the water contact angle of the compressed wood. The mechanical performance of US＆HW achieved an excellent grade, with a score of 48, while all six processing performance grades of US＆HW exceeded Grade 3, surpassing those of both USW and Ctrl. The finishing performance of the US＆HW was good, although slightly lower than that of USW in terms of ball impact performance. And the adhesion, hardness and abrasion resistance indexes of the paint film meet the requirements of excellent products in the standard.