Low Temperature Behavior of Epoxy-Rubber Particulate Composites

摘要

Toughness and mechanical property data are presented for a CTBN-rubber modified epoxy resin in the temperature range 20C to -110C. A toughening model based on the ultimate strain capability and tear energy dissipation of the rubber, present as dispersed microscopic particles in an epoxy matrix, is used to explain the suppression of composite toughness (G(Ic)) observed below -20C. The toughness loss is attributed to a glass transition near -40C in the epoxy resin which forms not only the primary matrix phase but also occlusions in the rubber particles themselves. On this basis a severe loss in ductility of the particles is anticipated which, along with reduced molecular mobility in the epoxy matrix, can account for an overall decrease in composite toughness. The low temperature data, used to test the particle stretching-tearing model for toughening, are found to be consistent with the proposed theory.