An assessment of mechanical behavior of environmentally conditioned fibre reinforced polymer composites

Abstract

Fibre reinforced polymer(FRP) composites are one of the most commonly used materials due to their adaptability to diverse environmental conditions and the comparative ease of combination with different materials to perform definite purposes and reveal advantageous properties. The components made up of fibre reinforced polymeric composites are exposed to temperature variations (thermal shock, thermal spike, low temperature environment, high temperature environment, freeze thaw), humidity variations, UV radiation and often the combined exposure of these environments leads to more detrimental effect on the performance of the composites during fabrication, in-service time and storage. Further, rate of loading can significantly change the mode of failure. The present experimental investigation deals with the mechanical behavior of FRP composites exposed at low temperature and thermal spiking conditioning with different loading rate and holding time. The glass/epoxy samples are exposed to ambient temperature, -20 °C, -40 °C and -60 °C temperatures and tested in 3-point bending test at 1, 10, 100, 300, 600, 1000 mm/min loading rates. Also, the thermal spike conditioning of glass/epoxy and carbon/epoxy samples were carried out at 50 °C, 100 °C, 150 °C, and 200 °C temperatures for a holding time of 5, 10, 15 and 20 minutes respectively and then tested for the interlaminar shear strength (ILSS) assessment in short beam shear (SBS) test at 1,100, 200, 700 and 1000 mm/min loading rates. Scanning electron microscopy (SEM) analysis was performed to identify various degradation mechanisms in fractured samples. Also, DSC measurement have been done to evaluate the glass transition temperature (Tg) is very important because it calculates the critical service temperature of the polymer composites. From FTIR analysis it is further confirmed that these environmental conditionings affects the bonding characteristics of the polymeric composites.