Determination of free surface energy values for ceramic materials and polyurethane surface-modifying aqueous emulsions

Abstract

Taking advantage of physical models developed by van Oss-Good and Neumann, which describe relations between surface free energy values for solids and wetting liquids, and making use of the contact angle values for Al 2O 3 and ZrO 2 surfaces and standard liquids with known values of surface energy, which were measured by means of the optical goniometer, surface free energy values as well as their components representing long-range interactions and acid–base interactions for the surfaces of the studied solids were evaluated. Analogical calculations were carried out for the comparative polymer materials—PTFE and PET. On the basis of the obtained data, and based on measured contact angle values for PET surfaces with water emulsions, free energy values were determined for newly synthesised polyurethane ionomers as well as for those ionomer emulsions additionally modified with vinyl monomers. It was found that the surface energy values for the synthesised polyurethane emulsions were predominantly affected by the structure of polyol and urethane segments, while the type of ionogenic segments influenced the quantity of acid–base interactions as well as the quantity of dispersal interactions. The effect of interactions between the surface of ceramic powders and aqueous emulsions on applicability of such systems as efficient binders in moulding green ceramic ware was discussed.