Measurement of the Mechanical Properties of Thin Film Polymers at Cryogenic Temperatures

Many applications require specific knowledge of thin film polymeric properties at cryogenic temperatures. In particular, applications in pressure vessels and structural components require understanding of the mechanical properties of polymers. The use of polymeric and composite materials has a strong potential to replace metals and decrease the mass of spacecraft while providing lower thermal conductivity for future space exploration missions. There is limited mechanical property data of thin film polymers available at cryogenic temperatures to evaluate these materials for such applications. In order to quantify material properties such as Young's Modulus and ultimate strength at cryogenic temperatures, a new experimental device has been constructed. This test apparatus uses pressurized liquid nitrogen to deform a polymer film disk and a laser displacement sensor to measure the resulting deformation. In this method, the liquid nitrogen pressure is slowly increased to provide incremental loads for evaluation. Several materials with known bulk modulus at 77 K were tested along with novel materials that are on the cutting edge of polymer science. The test setup and test results are presented here for discussion and further study.