Stability of oil-based dispersions containing poly(tetrafluoroethylene) micropowder

Micropowder of poly(tetrafluoroethylene) (PTFE) can be used in base oils to improve the tribological properties significantly, if oil molecules are covalently linked to primary PTFE particles in the dispersion. Enhanced properties are not only determined by the amount of PTFE micropowder added to the oil but as well by the surface charge, radical concentration, and the size and distribution of PTFE particles in the oil phase. emical compatibilization (=cc) between PTFE micropowder and ester oil by the use of two types of PTFE micropowder, which differ in radical concentration and the amount of functional groups is shown. The concentration of PTFE micropowder in the dispersions was varied from 5 to 20 wt%. Both the pure PTFE micropowder and the oil-PTFE-cc dispersions were characterized by ESR and FTIR spectroscopy as well as by zeta potential measurements. Rheological and tribological tests were performed on the ester oil and the oil-PTFE-cc dispersions. Qualitative differences are discussed in terms of particle interactions, dispersion stability, chemical compatibilization efficiency and the amount of functional groups. elation between flow properties and surface charge of the PTFE particles within the dispersions was obtained. The influence on tribological properties is discussed as well.