ESTIMATION OF THE SURFACE-TENSION OF A SOLID - APPLICATION TO A LIQUID-CRYSTALLINE POLYMER

The different methods available in the literature to calculate the sur face tension of a solid from contact angle measurements are discussed and compared. The discussion is based on the contact angles of water, glycerol, and diiodomethane measured at 20 degrees C on the surface of a side-chain liquid crystalline polymer, Some discrepancies exist amo ng the results obtained with the different methods, mainly between the values yielded by Neumann's equation and those obtained with approach es that postulate the decomposition of the surface tension into severa l terms associated with different types of molecular interactions (met hods of Owens and Wendt and of Good and van Oss). The physicochemical basis of these various treatments is discussed. (C) 1997 Academic Pres s.