Accession Number : ADA301630

Title :   Spectroscopic Comparison of Effects of Electron Radiation on Mechanical Properties of Two Polyimides.

Corporate Author : NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CEN TER

Personal Author(s) : Long, Edward R., Jr. ; Long, Sheila A.

PDF Url : ADA301630

Report Date : APR 1987

Pagination or Media Count : 20

Abstract : This report compares the differences in the radiation durabilities of two polyimide materials, Du Pont Kapton and General Electric Ultem. It provides an explanation of the basic mechanisms which occur during exposure to electron radiation from analyses of infrared (IR) and electron paramagnetic resonance (EPR) spectroscopic data for each material. The molecular model for Kapton was, in part, established from earlier modeling for Ultem (pp. 1293-1298 of IEEE Transactions on Nuclear Science, December 1984). In this respect, the report also demonstrates techniques for understanding the durability of one complex polymer based on the understanding of a different and equally complex polymer. The spectroscopic data showed that the primary radiation-generated change in the tensile properties of Ultem (a large reduction in tensile elongation) was due to crosslinking, which followed the capture by phenyl radicals of hydrogen atoms removed from gem-dimethyl groups. In contrast, the tensile properties of Kapton remained unchanged because radical-radical recombination, a self-mending process, took place. (MM)

Descriptors :   *POLYMERS, *COMPOSITE MATERIALS, *POLYIMIDE PLASTICS, MECHANICAL PROPERTIES, SPACECRAFT, STRESS ANALYSIS, SPECTROSCOPY, STIFFNESS, TENSILE PROPERTIES, FIBER REINFORCED COMPOSITES, GRAPHITE, MATRIX MATERIALS, STRENGTH(MECHANICS), ELECTRON BEAMS, MOLECULAR STRUCTURE, IRRADIATION, INFRARED RADIATION, ELONGATION, RADIATION DOSAGE, RADIATION DAMAGE.

Subject Categories : Polymer Chemistry
      Laminates and Composite Materials
      Plastics

Distribution Statement : APPROVED FOR PUBLIC RELEASE