Aging characteristics of glass fiber-reinforced polyamide in hot water and air

This article focuses on the accelerated aging behavior of a glass fiber-reinforced and heat stabilized polyamide grade. Accelerated aging of injection molded specimens was achieved by hot air exposure (HAE) and pressure cooker testing (PCT) at elevated temperatures. For both aging routines, characteristic aging indicators were found. For hot air exposure, the carbonyl index obtained from infrared spectra revealed superficial thermo oxidation. For pressure cooker testing, the development of a regular crack pattern and successive surface roughening were observed by light microscopy and laser confocal microscopy. This was accompanied by a significant reduction in molar mass assessed by viscometry. In addition, progressing degradation of mechanical performance was ascertained by tensile testing experiments. At the onset of material cracking, the molar mass was about 25% of the initial value. POLYM. COMPOS., 39:997-1005, 2018. (c) 2016 Society of Plastics Engineers