Effect of diffusion on composite materials properties

Abstract

Composite is an important structural material that is widely applied in several industry. In general, it is greatly desired for its high strength and stiffness and lighter weight. Despite these attractive properties, the application of polymeric composite in the marine industry is restrained due to the lack of in-service experience to validate theoretical design. Although, fatigue and tensile properties of composite are well-studied, the research on the effect of seawater on these performances is limited. This paper seeks to investigate the diffusion effect of seawater on the mechanical properties of woven glass fibre-reinforced bismaleimide (GF/BMI) composites. ±45° laminates of the composites mentioned were used as test specimens and were immersed in simulated seawater at 30°C, 50°C and 80 °C. The amount of moisture absorped by the immersed specimens were analysed. The non-immersed dry specimens and the specimens immersed at 50°C and 80 °C were then subjected to static tensile and dynamic fatigue tests. The results obtained showed that temperature increases the rate of moisture diffusion. Also, moisture and temperature were found to degrade the performance of the composite for the tensile and fatigue tests. The properties of composite materials changes with different constituent materials. Also, the performance of composites varies greatly with environmental condition. Presently, no single theory can be postulated to model the performance of GF/BMI composites against temperature and moisture. Hence, the result of this project serves as a supplement to the finding of past and on-going researches and contributes to the investigation on the suitability of GF/BMI composites in marine application.