Photo-oxidation of poly(ethylene terephthalate) films intended for photovoltaic backsheet

The photodegradation of 36 mu m thick poly(ethylene terephthalate) film under artificial weathering conditions has been investigated. A weatherometer was used to expose samples to a broad wavelength range of light in an oxidative environment, replicating outdoor exposure. Irradiations were also performed using UV lamps of wavelengths 302 and 365 nm light, in an oxidative environment. After exposure, the extent of degradation was determined using attenuated total reflectance Fourier transform infrared spectroscopy, diffuse reflectance infrared Fourier transform spectroscopy, UV-visible spectroscopy, fluorescence spectroscopy, differential scanning calorimetry, contact angle measurements, and scanning electron microscopy. Results show the production of a series of degradation products, including carboxylic acid end groups, anhydrides, aldehydes, quinones, and monohydroxy terephthalate groups. (c) 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 137, 48623.