Abstract
Poly(ethylene terephthalate) films were irradiated in a carbon‐arc Fade‐Ometer and in a xenon‐arc Weather‐Ometer. The changes in tensile properties, intrinsic viscosities, infrared absorption, and fluorescence emission spectra resulting from these irradiations were measured. Quantitative comparisons between changes in surface (ATR) and transmission infrared spectra, in conjunction with the other results obtained, have established the importance of surface reactions in the photodeterioration of poly(ethylene terephthalate).