Moisture Diffusion and Thermal Aging Effects in Glass Fibre Reinforced Polymer Epoxy Laminates

Abstract

Polymeric composites are inherently sensitive to environmental factors such as temperature, exposure to liquids, gases, electrical fields and radiation. Static and dynamic mechanical loads can interact with environmental parameters and accelerate the degradation process. Moisture absorption behavior of Polymer epoxy Nano composites (PNC) in water and saline conditions is a complex phenomenon. Moisture diffusion weakens the fiber/matrix interface which leads deterioration of Mechanical properties. Hygrothermic aging of two configurations: (i) E-glass fiber epoxy laminate (EEE) (ii) E-glass fiber lamina sandwitched between C-glass fiber laminas (CEC) for neat and 2% clay loading were studied for their suitability in humid applications. The specimens were exposed to water and saline environment at 45 oC temp for duration of 7 day, 15 day and 30 days. The specimens were periodically weighted for moisture absorption and tested Mechanical properties (Ultimate tensile strength, flexural strength) & Microscopic behavior. The maximum moisture absorption was observed for 0% EEE epoxy laminates and minimum for 2% CEC epoxy laminates. Diffusion mechanism was studied on the basis of Ficks law of diffusion. It was found that diffusion coefficient (D) was largest for 0% EEE and lowest for 2% CEC laminates. Water absorption increases with increase in immersion time for all the samples. Water uptake is rapid and linear in the beginning of exposure after which it slows down and reaches saturation level. All Glass fiber epoxy laminates have tendency to absorb more water in saline environment. Although all the nanocomposites undergo degradation and lowers in mechanical properties subjected to hygrothermic aging, CEC laminates shows better results in Tensile and flexural strength than three ply E glass fiber epoxy laminates. The experimental observations were tested and confirmed by SEM.