EVALUATION OF THE LIFSHITZ VAN-DER-WAALS ACID-BASE APPROACH TO DETERMINE INTERFACIAL-TENSIONS

In an attempt to determine the solid surface tension components of the solid surfaces FC721, FEP, and PET, by using the Lifshitz-van der Waa ls/acid-base approach from the measurement of contact angles of differ ent polar and apolar liquids, the solid surface tension components, ga mma(s)LW, gamma(S)+ and gamma(S)-, were found to be inconsistent and s trongly dependent on the liquids used. Accordingly, these solid surfac e tension components are not unique material properties of the solid s urfaces and the acid-base approach is not applicable for the determina tion of solid surface tension components from contact angles. In addit ion, occurrence of negative values for the square root of gamma(S)+ an d gamma(S)- suggests questionable physical meaning of the solid surfac e tension components, gamma(S)+ and gamma(S)-. It is also shown that t he inconsistent and negative values of gamma(S)+ and gamma(S)+ are not a consequence of contact angle errors or errors in gamma(L)LW values.