Degradation of Carbon Fiber-reinforced Epoxy Composites by Ultraviolet Radiation and Condensation

ABSTRACT: The degradation of an IM7/997 carbon fiber-reinforced epoxy exposed to ultraviolet radiation and/or condensation has been characterized. Based on observations of physical and chemical degradation it has been established that these environments operate in a synergistic manner that causes extensive erosion of the epoxy matrix, resulting in a reduction in mechanical properties. Matrix dominated properties are affected the most, with the transverse tensile strength decreasing by 29 % after only 1000 h of cyclic exposure to UV radiation and condensation. While, the longitudinal fiber-dominated properties are not affected for the exposure durations investigated, it has been noted that extensive matrix erosion would ultimately limit effective load transfer to the reinforcing fibers and lead to the deterioration of mechanical properties even along the fiber dominated material direction. KEY WORDS: carbon fiber-reinforced epoxy, environmental degradation, ultraviolet radiation, condensation, mechanical properties, tensile strength