Influence of Electron Radiation and Temperature on the Cyclic,Matrix Dominated Response of Graphite-Epoxy

Abstract

The effects of electron radiation and elevated temperature on the matrix dominated, cyclic response of standard T300/934 and a chemically modified T300/934 graphite-epoxy are characterzed. Both materials were subjected to 1.0 x 10¹⁰ rads of 1.0 MeV electron ir radiation, under vacuum, to simulate 30 years in geosynchronous orbit. Cyclic tests were performed at room temperature (75°F/24°C) and elevated temperature (250°F/121 °C) on 4-ply unidirectional laminates to characterize the effects associated with irradiation and elevated temperature. Both materials exhibited energy dissipation in their response at elevated temperature. The irradiated modified material also exhibited energy dissipation at room temperature. The combination of elevated temperature and irradiation resulted in the most severe effects in the form of lower proportional limits, and greater energy dissipation. Dynamic-mechanical analysis demonstrated that the glass transition temperature, T_g, of the standard material was lowered 70°F (39°C) by irradiation, whereas the T_g of the modified material was lowered 50°F (28°C) by irradiation. Thermomechanical analysis showed the occurrence of volatile products generated upon heating of the irradiated materials.