Characterization of Several Polymer Surfaces by Streaming Potential and Wetting Measurements: Some Reflections on Acid-Base Interactions.

Several thermoplastic (technical, engineering, and high-performance) polymers were characterized using contact angle and electrokinetic measurements. From the measured contact angles of various test liquids on polymers, we calculated the solid surface tensions using the different approaches to determine them and compared the results. Zeta (zeta)-potential measurements gave information about the swelling behavior of the polymers in water, the surface chemistry, and the interactions with dissolved potassium and chloride ions. All investigated polymers displayed an acidic surface character. Comparing the results obtained from the zeta-potential measurements with the acid-parameter of the surface tension gamma(+) calculated from the measured "static" contact angles using the van Oss, Good, and Chaudhury approach revealed the same tendency. The correctness of the acid-base approach regarding the "overall" chemical surface character could be shown. However, it seems that the basic parameter gamma(-) obtained from the acid-base is greatly overestimated. Copyright 1999 Academic Press.