A STUDY OF A SIMULATED LOW EARTH ENVIRONMENT ON THE DEGRADATION OF FEP POLYMER

Spacecraft flying in a low Earth orbit environment require thermal bla nkets to provide protection from direct solar heat from the sun. Fluor inated ethylene propylene copolymer is one of the major components of these thermal blankets. In this study, the effect of a simulated low E arth orbit environment on FEP was investigated. UV and VUV degradation of fluorinated ethylene propylene (FEP) copolymer was studied using E SR and XPS. The ESR study revealed the formation of a terminal polymer chain radical. The stability of this radical has been investigated un der different environments. An XPS study of FEP film exposed to VUV an d atomic oxygen showed that oxidation takes place on the polymer surfa ce. The study revealed also that the percentage of CF2 in the polymer surface decreased with exposure time and the percentage of CF, CF3 and carbon attached to oxygen increased. SEM micrographs of FEP film expo sed to VUV and atomic oxygen produced a rough surface with regular und ulations similar to sand dunes. (C) 1998 John Wiley & Sons, Ltd.