Combustion-thermal-sprayed recycled poly(ethylene terephthalate)

Thermal-sprayed polymer coatings have been used as protection against corrosion and wear. In this study, poly(ethylene terephthalate) (PET) powder, which was obtained from postconsumer beverage bottles, was deposited on 1020 steel by low-velocity flame-spray technology. The chemical and structural changes in PET due to the thermal-spray processing were investigated with Fourier transform infrared spectroscopy and X-ray diffraction. Changes in tribological behavior were examined by pin-on-disk testing and three-dimensional profilometry. The results show that coatings had the same functional groups as the PET beverage bottles. However, the degree of crystallinity was modified. These changes were rationalized in terms of possible structural modifications of the PET polymer. The study showed evidence that the pin-on-disk wear developed by an abrasion process through a ploughing mechanism, although a fatigue mechanism could not be disregarded. A low friction coefficient between PET and steel was confirmed. In the as-sprayed condition, the PET coatings showed higher friction, likely because of a higher coarse debris production rate during the pin-on-disk testing. Heat treating the as-sprayed coating to increase the amorphous PET content improved the sliding behavior by increasing wear resistance. (C) 2004 Wiley Periodicals, Inc.