Review of Pneumatic Impact Sensitivity Data Obtained on Selected Polymers for Aerospace Applications

摘要

NASA started evaluating compatibility of polymers with oxygen more than 30 years ago. New test methods and a systematic approach to evaluate oxygen system hazards were developed. The new methods were used extensively to acquire data on a large number of polymers. NASA's batch-lot control strategy for qualifying spacecraft materials allowed acquiring extensive data, principally on the best candidates for aerospace usage. A review of pneumatic impact sensitivity data on selected materials for aerospace applications is provided; it includes data on polytetrafluoroethylene, Viton~(~R5) A, polychlorotrifluoroethylene, Vespel~(~R6) SP-21 and Vespel SP-1. Since the number of samples tested at each condition was large, the data are presented in terms of reaction frequencies. This is considered to be statistically defensible when compared with the uncertainties related to the pressure threshold data commonly reported. For most materials, the data presented were obtained from a large number of batches, thus minimizing potential bias caused by batch-to-batch variability.