Fabric Oil Repellency as Related to the Critical Surface Tension and Stiffness of Coating Material

Abstract

Although a low critical surface tension for wetting ( 15 dynes/cm or less) is necessary for oil repellency, examples of fluoropolymers with low critical surface tensions are cited that are ineffective for making wool textiles oil repellent. In contrast to effective polymers, these have relatively high glass transition temperatures (ahove 25°C) and are therefore more brittle. Scanning electron microscopy of fabrics coated with such ineffective materials supports the idea that such coatings are flawed, fragile, and poorly adherent.