Effects of hygrothermal cycling on the chemical, thermal, and mechanical properties of 862/W epoxy resin

The hygrothermal aging characteristics of an epoxy resin were characterized over a one-year period, which included 908 temperature and humidity cycles. The epoxy resin quickly displayed evidence of aging through color change and increased brittleness. The influence of aging on the material's glass transition temperature (T-g) was evaluated by Differential Scanning Calorimetry and Dynamic Mechanical Analysis. The T-g remained relatively constant throughout the year-long cyclic aging profile. Chemical composition was monitored by Fourier Transform Infrared spectroscopy, where evidence of chemical aging and advancement of cure was noted. The tensile strength of the resin was tested as it aged and this property was severely affected by the aging process in the form of reduced ductility and embrittlement. Detailed chemical evaluation suggests many aging mechanisms are taking place during exposure to hygrothermal conditions.