Outdoor weathering behavior of polyamide 6 under various climates in China

ABSTRACT The outdoor natural weathering of polyamide 6 (PA6) was performed at six national standard natural exposure stations (at Qionghai, Guangzhou, Qingdao, Lhasa, Hailaer, and Ruoqiang), which represented the six typical climates over China. The outdoor aging behavior was studied. We found that under high temperature and humidity in the areas of Guangzhou, Qionghai, and Qingdao, the concentration of the end carboxyl group of PA6 increased significantly and the molecular weight decreased because of serious hydrolytic degradation. This resulted in a deterioration of the mechanical properties, high yellowing degree, and serious damage of the sample surface. While in the areas of Lhasa and Ruoqiang, with the relatively low temperature, humidity, and oxygen content in the atmosphere, the aging degree and corrosion index were low, and this resulted in the slow change of performances. Humidity, temperature, and rainfall may be the main environmental factors affecting the degradation of PA6. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44231.