Effect of ultraviolet radiations on interlaminar shear strength and thermal properties of glass fiber/epoxy composites

Abstract

Abstract Fiber-reinforced polymer (FRP) composites have entered diverse fields like aerospace, defense, marine as well as civil, both in terms of research and commercial applications. The use of FRP composites as structural material calls for more research on the effect of environmental conditions upon their different properties. This research work presents a study on the effect of ultraviolet (UV) radiation on FRP composites. Here, the glass fiber/epoxy (GE) composite samples have been subjected to UV radiations of 365 nm wavelength at room temperature. The effect of these radiations on the interlaminar shear strength (ILSS) and the glass transition temperature of the composite samples has been measured at regular intervals for a total of 1080 h. The Short Beam Shear (SBS) tests were done not only at room temperature but also at an elevated temperature of 70 °C. The results show an increase in ILSS in the first 15 days, followed by a decrease in subsequent tests, both at room temperature as well as at 70 °C. The changes, however, are more significant at higher temperature. The glass transition temperature (Tg), measured using Differential Scanning Calorimetry (DSC), does not vary much with an increase in UV exposure duration. Fourier Transform Infrared Spectroscopy (FTIR) has been performed to obtain spectral resolution data to analyze the changes in molecular structure after exposure to UV radiation.