The Effect of Nuclear Reactor Radiation on the Electrical and Mechanical Properties of Epoxide Polymers

Abstract

The effect of nuclear reactor radiation on the volume resistivity, bulk compressibility, specific volume, and hardness of three epoxide polymers was studied. The polymers were thermally polymerized and then subjected to varying radiation doses in the enriched uranium, water moderated, heterogeneous nuclear reactor located at the University of Maryland. Changes in the volume resistivity as a function of temperature for the various radiation doses was then determined by the use of an electrometer to measure the potential drop across the specimen. The effect of radiation on the bulk compressibility was determined by means of a special compressibility tester over the pressure range one to 8,000 atmospheres and temperatures 25°C to 250°C. The specific volume and hardness were measured for each sample before and after irradiation using standard techniques. The temperature dependence of the electrical volume resistivity was initially increased by exposure to 2.5 Mrads. Further irradiation up to 25 Mrads caused severe degradation of the temperature dependence of the electrical resistivity for all epoxide polymers studied . The magnitude of the compressibility for the polymers was found to be relatively unaffected by irradiation up to 25 Mrads; however, determination of the pressure-induced glass transition yielded anomalous results. No significant change in the hardness of the polymers was noted after varying amounts of radiation. The specific volume of an aromatic cured epoxide was not affected to any extent , but the aliphatic cured polymer showed a decreased specific volume.