Effect of hygrothermal aging on static behavior of quasi-isotropic CFRP composite laminate

The Carbon fiber reinforced polymer (CFRP) composites used in offshore and marine industries tend to deal with high temperatures and humid conditions throughout its life. This work investigates the effect of long term hygrothermal aging on the physical and mechanical properties of CFRP composites. The IMA/M21 carbon fiber epoxy quasi-isotropic Multidirectional laminate with stacking sequence [+/- 45, 0, 90](2S) was fabricated using vacuum assisted resin transfer moulding. The static specimens were immersed in room temperature (RT) and comparatively high temperature (HT) tap water at 70 degrees C up to saturation. The kinetics of moisture absorption was monitored up to saturation as a function of time which followed a two-stage model. The static strength of virgin, RT aged and HT aged specimens were determined with a constant cross-head speed of 1 mm/min. The post-saturation static strength showed a major drop however reduction in compressive strength was higher than tensile strength in a matrix dominated failure. Similarly, the hygrothermal aged specimen showed higher moisture absorption and strength reduction as compared to RT aging. The SEM and FESEM micrographs clearly revealed matrix erosion and fiber-matrix interfacial debonding after saturation. The TGA analysis of the moisture absorbed specimen showed a degraded physical property.