WETTING PROPERTIES OF TETRAFLUOROETHYLENE AND HEXAFLUOROPROYLENE COPOLYMERS

摘要

It has been shown that the determining factors in the wetting of low-energy solid surfaces are the nature of the atoms in the surface and their physical packing. Of all solid organic polymers polytetrafluoroethylene is known to have the lowest surface energy and thus the lowest critical surface tension of wetting (yc). In this study the wettability of a series of copolymers of tetrafluoroethylene with hexafluoropropylene by a variety of organic and inorganic liquids was examined. The results show that these solid plastics have critical surface tensions which are even lower than that of solid polytetrafluoroethylene. As anticipated, the progressive increase .in the proportion of perfluoromethyl side chains in the polymer introduces a higher concentration of exposed –CF3 groups in the surface, which in turn progressively reduces yc. By extrapolation yc of a polyhexafluoropropylene has been calculated to give the value 15 dynes/cm.