Effects of Heat Sterilization and Vacuum Exposure on Some Low-Density Heat-Shield Materials.
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CEN TER
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The effects of dry heat sterilization for 92 hours at 135 deg C in flowing nitrogen and 200 hours of exposure at 66 deg C to pressures in the 10-5-Nm2 range upon the thermochemical properties of five blown-foamed and five molded composite heat-shield materials have been determined. Differential thermal analysis DTA was employed to follow the changes which occurred in each material as a result of sterilization and vacuum exposure. The results show that, on the whole, the composite materials have greater sterilization mass losses than the foamed materials and that the high-vacuum losses of both types of material are approximately equal. During high-vacuum exposure, the mass loss was approximately 1 percent after 200 hours of exposure, and at 200 hours the rate of mass loss ranged between 2.5 x 10 -4 and 11.1 x 10-4 percent per hour for most of the materials.
- Laminates and Composite Materials
- Protective Equipment