The effects of superheated steam heat-treatment on turpentine content and softening point of resin

Studying on superheated steam heat-treatment (SSHT) of resin can provides strong support for the research on wood drying and degreasing. Resin exudation remains a significant industry concern, limiting the environment in which pine lumber can be used. Hence, a two-stage SSHT was conducted on the resin, and the softening point (SP) and residual turpentine content (RTC) of the resin are determined by Thermomechanical analysis (TMA) and Thermogravimetric analysis (TGA). The effects of oxygen content and treatment time in the drying chamber on the removal efficiency of turpentine were also studied. Finally, the color of the heat-treated resin was measured, and the chemical composition of the heat-treated resin was analyzed by Fourier Transform Infrared Spectroscopy (FTIR) and X-ray photoelectronic spectroscopy (XPS). The results show that SSHT can remove turpentine from resin and increase the SP of resin, and the oxygen content significantly affects the removal efficiency of turpentine. The increase in the SP of the resin is due to the dehydrogenation, isomerization, and oxidation reactions of the resin caused by the heat-treatment. Therefore, the SSHT of resin can be adjusted and applied to the wood drying process to avoid resin exudation during the use of resinous wood products.