Thermal shock behavior of hydrothermally conditioned e-glass fiber/epoxy composites

The glass fiber-reinforced polymer composites suffer from significant moisture absorption properties, moisture due to both the ambience and direct immersion in ordinary water during the course of their practical applications. The quantity of moisture absorbed and its effect on the composite component in any engineering application is also severely influenced by the temperature fluctuations. Hence the present work aims at evaluating the glass fiber/epoxy composite under hydrothermal exposure coupled with up and down-thermal shocks for various lengths of time. Inter-laminar shear strength (ILSS) values of shocked and non-shocked composite specimens were determined using INSTRON-1195 testing system. Low-temperature differential scanning calorimetry was used to monitor the glass transition temperature (T_g). A longer hydrothermal exposure showed an increase in the ILSS value after an initial low value. The ILSS seemed to vary with up and down-thermal shock differently for hydrothermally treated sample. Despite little variation in T_g value, the depression in the same was observed under up-thermal shock compared to down-thermal shock conditions. The fractographs of shocked and non-shocked specimen, as obtained from scanning electron microscope, divulged the chief mode of failure viz. fiber fragmentation and delamination.