Estimation of the Surface Energy and Acid-Base Properties of Wood by Means of Wetting Method

The important surface energy and acid-base properties for pine wood (Pinus silvestris L.) have been estimated by using two contact angle techniques (CAT), e.g., the sessile drop method and the Wilhelmy plate method, respectively. According to the results, the pine wood may be characterized as a low surface energy polymer due to its low surface energy. The surface energy, γS, for the pine wood was being larger in the direction parallel to the grains as compared with the perpendicular direction. The Lifshitz-van der Waals (LW) energy component, γSLW, is the major energy component for the pine wood as compared with the acid-base energy component, γSAB. Furthermore, it seems that the LW energy component, γs,LW, of pine wood is independent of the choice of wetting methods and of the chemical composition of the surface. However, the surface acid-base (AB) energy component, γSAB, for the pine wood seems to be dependent on the wetting methods chosen. Subdivided into its contributions, the surface of pine wood seems to be weaker in the acidic energy parameter, γs+, and stronger in the basic energy parameter, γs-. Rough estimation of the contact angle hysteresis (CAH) and surface roughness (SR) has also been measured separately in the parallel direction and the perpendicular directions, respectively.