The role of interfacial free energy in wettability, solubility, and solvent crazing of some polymeric solids

Abstraet-The laser contact angle goniometry technique was applied to measure the wettability of water droplets on polymer surfaces in different normal alkanes. Using the modified two-liquid contact angle technique and the model recently proposed by us, we can determine the dispersive and non-dispersive (acid-base) contributions to the surface free energy for polymeric solids of high surface energy. The interfacial free energies between several polymers and various liquids were calculated, using our model, from the constitutive properties of the two component phases. These data can, in turn, be used for evaluating the wettability of liquids on polymer surfaces, and the dissolving and solvent crazing/cracking behaviors of polymers in liquids. A good correlation between the critical crazing strain and the interfacial free energy was established. Attacking and non-attacking liquids were separated by a cut-off interfacial free energy of about 3 mJ/m2. In addition, excellent agreement was found between the predicted and the experimental work of adhesion values.