A novel method for surface free-energy determination of powdered solids

Interfacial solid/liquid interactions play a crucial role in wetting, sprea ding, and adhesion processes. In the case of a flat solid surface, contact angle measurements are commonly utilized for the determination of the solid surface free energy and its components. However, if such a surface cannot be obtained, then the contact angle can not be measured directly. Usually m ethods based on imbibition of probe liquids into a thin porous layer or col umn are applied. In this paper a novel method, also based on the capillary rise, is proposed for the solid surface free-energy components determinatio n. Actually, it is a modification of the thin column wicking method; simila r theoretical background can be applied together with that appropriate for the capillary rise method of liquid surface tension determination. The prop osed theoretical approach and procedure are verified by using single glass capillaries, and then alumina and ground glass powders were used for the me thod testing. Thus obtained surface free-energy components for these solids , for both glass and alumina, agree well with the literature values. (C) 20 01 Academic Press.