During recent decades positron annihilation spectroscopy has become a very powerful tool for the investigation of polymers. In particular, positron annihilation lifetime spectroscopy (PALS) yields valuable information about free volume and related properties. Moreover, special chemical information can be obtained. Now advances in positron beam technology also allow investigations of thin polymer films and surface regions. In this paper, we report the use, for the first time, of PALS to elucidate aging mechanisms in thin epoxy films, based on depth-resolved investigations of the epoxy films exposed to two different aging conditions. We also consider the results of IR external reflection absorption spectroscopy (IR-ERAS) and X-ray photoelectron spectroscopy (XPS) depth-profiling of the elemental composition. This additional information enables us to clarify structural modifications due to aging. Nitrogen depletion and a decrease in free volume were observed, especially in the near-surface region of the thin epoxy films.    «

During recent decades positron annihilation spectroscopy has become a very powerful tool for the investigation of polymers. In particular, positron annihilation lifetime spectroscopy (PALS) yields valuable information about free volume and related properties. Moreover, special chemical information can be obtained. Now advances in positron beam technology also allow investigations of thin polymer films and surface regions. In this paper, we report the use, for the first time, of PALS to elucidate...    »