Weatherability and wear resistance characteristics of plasma fluoropolymer coatings deposited on an elastomer substrate

The weathering characteristics of thin film formed from plasma polymerisation of perfluoro(methylcyclohexane) on an EPDM substrate under cold plasma process operated at 13.56 MHz was investigated using an ATLAS Ci 3000 Xenon weatherometer. The effects of weathering conditions on the chemical composition of the substrate and the coating were examined using photoacoustic Fourier transform infrared spectroscopy (PA-FTIR) and X-ray photoelectron spectroscopy (XPS). The wear behaviour was examined using scanning electron microscopy (SEM). The change in the surface morphological behaviour of the coating indicates that the mending line of the patch-wise coating deposition or the fissure/crack line of the coating is particularly sensitive to the initiation of decomposition. FTIR and XPS spectroscopic investigations confirm that under humid and UV conditions, elimination of fluorine and introduction of new oxygen-containing functional groups play predominant role in the decomposition of the coating. Plausible mechanisms of degradation for the elastomer and the coating have been proposed. The coated substrate shows superior abrasion resistance characteristics with respect to the neat elastomer. The adhesion between the substrate and the plasma polymer coating appears to be excellent and remains strong after weathering.