A rapid and highly sensitive evaluation of polymer composite aging with linear correlation to real-time aging

Abstract

Evaluation of polymer aging is very important for the long-term performance of polymer materials, but it remains a challenge to correlate accelerated evaluations with the real-time procedures. Here we develop a novel in-situ aging evaluation system for rapid and sensitive aging evaluations of polymer materials within hours under multiple environmental conditions. It is carried out by in-situ detecting the generation rate of trace gaseous degradation products, e.g. CO2, of polymer materials in a specially designed reaction cell during aging under environmental conditions with various UV irradiation, temperature and humidity. The advantages of this system were demonstrated by applying to evaluate the photo-oxidation of polypropylene (PP)–CaCO3 composites, including stability evaluation, aging status analysis, aging kinetics measurements and study on effects of UV irradiation intensity and humidity. The CO2 generation rate of PP-CaCO3 composites measured in this system is well correlated to carbonyl indices during 120-day natural weathering. A linear relationship was observed between the generation rate of CO2 and the natural logarithm of the carbonyl index. The activation energy of the photo-oxidation of PP-CaCO3 composites was calculated based on generation rates of CO2 at different temperatures in the range of 30–80 °C. The increase of UV irradiation intensity and humidity both enhanced the generation rate of CO2 of PP composites, and the presence of CaCO3 fillers promoted the sensitivity of PP photo-oxidation to both of UV irradiation intensity and humidity. This study provides a new approach to rapid and highly sensitive evaluation of polymer composite aging under multiple environmental conditions.