| Abstrakt: |
The determination of surface free energy of wood is an important parameter in applications suchas coating, painting and gluing. The simplest technique for that is measurement of contact angle. This technique has been used for the investigation of the effect of heat treatment of wood on thesurface free energy. Two wood species - aspen and grey alder - have been treated in a range oftemperatures from 140 to 180°C. With the sessile drop technique, series of contact angle datahave been collected and used to determine the corresponding surface energies and changes inwettability. The most commonly used approaches, Zisman, Owens-Wendt, Wu, equation of stateand acid-base theories, were applied. The results demonstrate that heat treatment affectswettability and solid surface energy, in particular, from the Owens-Wendt and Wu theories. Weknow that at higher treatment temperatures, the polar component of the surface energy for bothwood species decreases, while the dispersive component is almost constant. The experimentshave been conducted while trying to fulfil the same measuring conditions, but in any case, it wasnot possible to reach the thermodynamic equilibrium conditions assumed by Young's equation, due to chemical heterogeneity, surface roughness and capillarity. It is possible to improve theaccuracy of results using a larger number of probe liquids. [ABSTRACT FROM AUTHOR] |
