Response of E-Glass/Epoxy Composite to Up and Down-Thermal Shocks under the Influence of Varying Environmental Condition

Abstract

The glass fiber reinforced epoxy composites, like any other fiber reinforced polymer composites, offer many advantages over the conventional structural materials. These materials suffer from significant moisture absorption properties, moisture coming from both the ambience and direct immersion in ordinary/sea water during the course of their use. The absorbed moisture causes high residual stresses while badly affecting the structural integrity of the composite. The quantity of moisture absorbed and its effect on the composite component in any engineering applications is also greatly influenced by the temperature fluctuations. Thus to ensure the effective and safe use of these materials in various fields of application, it is imperative that these materials be evaluated under the exposure to the ambience as well as temperature fluctuations. The composites fabricated in the laboratory is exposed to hydroscopic, hygroscopic and seawater environment coupled with up-thermal and down-thermal shocks for various lengths of time. Their Inter laminar shear strength (ILSS) is determined using INSTRON. The Tg is determined using low temperature DSC. The mode of failure is analyzed through several micrographs as obtained by inspecting the broken surface using the SEM technique. The results establish that moisture ingression into the composite body is partly conducted by diffusion involving transport of water molecules into the matrix and in some cases into the fiber; longer exposures to moisture causing greater degradation of the composite assisting further moisture uptake by way of delaying the saturation level of moisture in the composite body.