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

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 120day 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 degrees 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. (c) 2021 Elsevier B.V. All rights reserved.