Response of Sea Water Immersed GFRP Composite to Thermal Shock

Abstract

The work involves examining the effects of sea water immersion and temperature fluctuations, precisely that of up and down thermal shocks (lower to higher and vice-versa), on the glass fiber /epoxy laminated composites. These effects are studied in terms of sea water absorption, degradation in inter laminar shear strength (ILSS), alternations in the glass transition temperature (T_g) as compared to the untreated samples and finally listing up of the mode of failure as established through scanning electron micrographs. The ingression of sea water is found to be anomalous, the rate of ingression picking up with time of immersion from an initial low value and then again slowing down with lapse of time. Shorter durations of exposure to up thermal shock exhibits an increasing trend in ILSS value while longer exposures do not affect the ILSS value much. The longest period of exposure to down-thermal shock causes a sharp decrease in the ILSS values. The T_g depression is more visible under up-thermal shock compared to that under down-thermal shock, the chief mode of failure being fiber pull out, fiber fragmentation and delamination.