University of North Texas 
W. Brostow 1, P. E. Cassidy 2, J. Macossay 2, D. Pietkiewicz 1, S. Venumbaka 2
1) Laboratory of Advanced Polymers and Optimized Materials (LAPOM), Department of
Material Science and Engineering, University of North Texas, Denton, TX 76203-5310,
USA
2) The Shell Center for Polymer Science & Technology, Department of Chemistry, Southwest
Texas State University, San Marcos, TX 78666, USA
ABSTRACT
Contact angles of free liquids on solid samples were measured and the van Oss-Good method was applied for evaluating surface tensions of the solids. A parachor method was used for comparison: in this case the respective values were calculated for the polymer solids from molecular and group contributions. Surface tensions were computed from the parachors and the two methods compared. Effects of varying the flouropolymer added to the epoxy before curing are discussed. For a given fluoropolymer, effects of changing its concentration on surface tension have also been evaluated and compared to the changes in scratch resistance (scratch penetration depth, recovery depth) and in static and dynamic friction. Morphological and phase structures are reflected in all these properties, showing a strong connection between the surface tension and tribological properties.
© 2003 Society of Chemical Industry