Elucidating the Impact of Microbial Interactions on Fiber-Reinforced Polymers Composites

Abstract

Fiber-reinforced polymer composites (FRPC), especially vinyl ester-based polymer composites, have become an attractive option for lightweight structural applications due to their excellent moisture-resistance properties. Degradation of FRPCs due to environmental factors such as moisture and temperature are well studied and recognized in the literature. Di-ionized (DI) water and synthetic seawater have been primarily considered to evaluate polymer composite degradation. Little to no attention has been paid to microbes present in natural environments, and their interactions with polymer composites that can potentially aggravate degradation. A few investigations have explored specific fungus or microbial environment to understand their effects on polymer composite degradation. However, no previous study has explored the influence of naturally occurring diverse microbial communities in the environment, such as soil or marine waters, on the performance of polymer composites. Therefore, in this study, we elucidate microbial induced damage on polymer composite materials from naturally occurring diverse microbial communities in natural soil, and further establish their impact on the physical and structural integrity of these composites. Due to the diverse nature of the microbial community, the observations and conclusions from this study can be extended to other natural environments. Carbon fiber reinforced vinyl ester composites were subjected to DI water, autoclaved and ad received soil water for up to 20 weeks. We periodically measured their nanomechanical (nanoindentation) and thermal properties (Thermogravimetric analysis), which showed a reduction these properties in the presence of microbes. Reduction in thermal properties indicated polymer chain scission in composite samples, which was related to hydrogen bond formation through Fourier-transform infrared spectroscopy measurements. Reduction in the amount of dissolved organic carbon content in soil water with time indicated the consumption of carbon by microbes. Additionally, analyzing the biofilms grown on polymer composite samples using metagenomics in collaboration with microbiologists, we confirmed microbial growth. In summary, an in-depth study was conducted to elucidate degradation mechanisms of polymer composites due to microbial activity.