Characterizing the chemistry of yellow-poplar surfaces exposed to different surface energy environments using DCA, DSC, and XPS

Surface energy changes in extracted and unextracted yellow-poplar upon exposure to aluminum, teflon, and heat/air surface treatments have been described using dynamic contact angle (DCA) and X-ray photoelectron spectroscopy (XPS) analysis. Results show that the surface molecular orientation of yellow-poplar can be controlled by increasing the temperature above the Tg of lignin with exposure to either an environment of higher (aluminum) or lower (teflon) surface energy. Above the Tg, increases in free volume allows greater molecular mobility that enables increased diffusion of extractives to the surface and reorientation of polymer molecules and/or functional groups. Above the Tg, the wood with aluminum treatment is greater in surface energy than the control and other surface treatments. The surface energy obtained from teflon treatment, at temperatures above the Tg, was lower than heat/air treatment. There was less preferential reorientation evident from all surface treatments with the absence of extractives