Interfacial Micromechanics And Effect Of Moisture On Fluorinated Epoxy Carbon Fiber Composites

Abstract

Carbon fiber composites have witnessed an increased application in aerospace and other civil structures due to their excellent structural properties like specific strength and stiffness. For example, the Airbus A350 XWB contains 53 % composites whereas the Boeing 787 Dreamliner contains 50 % composites by weight. Unlike other structural materials like Steel and Aluminum, Carbon fiber composites have not been as widely studied and hence, their increased application is also accompanied with a serious concern about their long-term durability. Many of these applications are exposed to multiple environments like moisture, temperature and UV radiation. Composites based on conventional epoxies readily absorb moisture. However, scientists at NASA LaRC have synthesized novel fluorinated epoxies, which show reduced moisture absorption and hence potentially better long term durability. The aim of this project is to study the effect of moisture absorption on fluorinated-epoxy based carbon fiber composites and its comparison with conventional epoxy carbon fiber based composites. Microbond tests were performed on fluorinated and non-fluorinated epoxy based single fiber microcomposites before and after boiling water degradation. It was observed that fluorinated epoxy based single fiber coupons underwent relatively increased degradation of interface as compared to their non-fluorinated epoxy counterparts.