Influence of moisture and salinity on property degradation of nano-engineered epoxy polymers for offshore applications

This study has attempted to investigate the influence of major environmental degradation factors for offshore and coastal structures, such as moisture and salinity, on epoxy-based bonded composite systems and to identify the means of degradation of the same. Exhaustive experimental investigations have been carried out with different salinity levels (0%, 2.5% and 5%) and exposure periods (45 days to longer time periods (>1 year)) to determine the influence of the same on the mechanical property degradation of epoxy polymers. The effect of degraded properties on the performance degradation of bonded epoxy composite systems in terms of damage pattern and load-carrying capacity has been investigated using numerical simulations with non-linear material models and traction-separation interface behaviour. Further, it is also attempted to fundamentally engineer the epoxy polymers using nanosilica to improve their mechanical properties and environmental resistance. Finally, diffusion tests have been performed on the plain and nanoengineered epoxy polymers to understand the change in diffusion mechanisms due to nanoengineering, and a correlation has been established between the diffusion behaviour and the mechanical property degradation. The findings of this study will lead towards the development of stronger and more durable epoxy-bonded composite systems for marine applications.