Evaluation of structural integrity and mechanical behavior of advanced FRP composites

Abstract

In this investigation, microstructural integrity at the interface and consequently an implicating effect on mechanical behavior was analyzed. In the light of Fourier transform infrared spectroscope (FTIR imaging) and temperature-modulated differential scanning calorimeter, a sorption mechanism was established. Thermal spike and thermal shock treatment was carried out at 150 and 80°C, respectively. This suggested that fiber/matrix adhesion rests on the structure and properties of both the fiber and matrix in the region near the interface during the hygrothermal treatment. The carbon surface was found to selectively absorb the tertiary amine catalyst and to modify the chemical state of the cured resin apparently through the effects of absorbed water. The higher values of glass transition temperature (Tg) resulted in longer immersion time and higher exposure temperature. Together, these techniques provide a comprehensive picture of chemical and physical changes at the interphase region. Thermal spike of hybrid composite at 150°C temperature might possibly improve the adhesion level at the interface. Whereas, in case of thermal shock treatment at 80°C the fall in inter-laminar shear strength value at higher number of cycles. This degradation of the interface region has been monitored by scanning electron microscope analysis.