Chemical Attack of Graphite/Epoxy by Hydrogen Peroxide

Abstract

Techniques for studying the mechanisms of chemical corrosion in fiber-reinforced plastics are of considerable importance. The most common analysis technique for studying chemical changes in polymers is Fourier transform infrared (FT-IR) spectroscopy. For polymers reinforced with graphite fibers, however, study of the matrix is hindered by the presence of the graphite, which strongly absorbs IR radiation in a broad band of wavelengths. The purpose of this study was to investigate the degradation of AS-4/3501-5a graphite/epoxy composite material exposed to solutions of hydrogen peroxide. Evidence was also sought for degradation in high pH (up to pH = 12) solutions. After long-term environmental exposure, a simple gravity flotation technique was used to separate the epoxy matrix from the graphite fibers for FT-IR analysis. The resulting spectroscopic evidence indicates that hydrogen peroxide attacks the secondary amines in the cured epoxy structure. No evidence of attack by high pH solutions was found.