Calculation and Interpretation of Surface Free Energy of Wetting of E-Glass by Vapors

The surface free energy of wetting of E-glass by water and benzene vapors was calculated from Bangham and Razouk's free-energy equation. The method of Fu and Bartell for determining specific surface area was used to analyze the microstructure. The surface free energies, which were computed from adsorption isotherms obtained at temperatures from 18° to 20°C, had values from -235 to -254 ergs/cm² and -71.1 to -72.4 ergs/cm² for water and benzene adsorption, respectively, depending on temperature, surface geometry, and sample treatment. The lower affinity of E-glass for benzene, which resulted in a smaller work of adhesion, suggests that active adhesion of hydrocarbons is impossible in the presence of bulk water. Microstructural analysis indicated that the water-modified E-glass surface contains micropores 23 Å in diameter.