Dose Rate Effects in Polymer Materials Irradiated in Vacuum

Le résumé fourni par la source

The most reliable information on the polymeric material radiation resistance and lifetime may be obtained in the tests conducted under operation conditions. An important problem of the environment simulation is the adequacy of the accelerated test results, because the dose rates used in the test and under operation conditions test may differ up to several orders of magnitude. The natural way of acceleration is valid only when the change in a material property does not depend on the dose rate. It is well known that under irradiation in air environment the dose rate effects in polymers are very significant and connected with oxidizing radiation destruction. As a rule, they are taken into account for polymer materials used, e.g., in nuclear energy facilities. We will examine an opposite situation-irradiation of materials in vacuum that is typical for operation in space environment. It is often assumed that the irreversible radiation changes in the polymer properties do not depend on the dose rate. On the basis of available experimental data (including unpublished results obtained in our laboratory) we will show that there are remarkable dose rate effects in physical-chemical and operational (mechanical, electrical, thermal and optical) properties for a wide variety of polymers irradiated in vacuum. These effects reach sometimes an order of value and in a number of cases have a non-monotonous character. These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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