Accession Number:

AD0631831

Title:

THERMAL DEGRADATION OF AN AROMATIC POLYPYROMELLITIMIDE IN AIR AND VACUUM: III. PYROLYTIC CONVERSION INTO A SEMICONDUCTOR,

Descriptive Note:

Corporate Author:

JOHNS HOPKINS UNIV SILVER SPRING MD APPLIED PHYSICS LAB

Personal Author(s):

Report Date:

1964-10-01

Pagination or Media Count:

35.0

Abstract:

The pyrolytic conversion of N,N-p,p-oxydiphenylene pyromellitimide to semiconducting products is discussed as supported by data on electron paramagnetic resonance EPR absorption, specific resistivity, weight loss, density, and composition. Specific resistivities as low as 10 to 0.05 ohm-cm were obtained by vacuum pyrolysis between 620C and 850C with a simultaneous increase in density to 1.65 gcc. The region between 575C and 620C was characterized by no appreciable weight loss, increase in density, and a sharp drop in the specific resistivity. These changes could be related to an internal reorganization of the polymer to semiconducting products, for which an activation energy of 25 plus or minus 3 kcal was calculated. The development of semiconduction in the pyrolysates occurs well below the graphitization temperature and with the retention of considerable quantities of nitrogen and oxygen. The results are explained in terms of increased mobility of current carriers facilitated by enhanced pi-orbital overlap, which in turn arises from a molecular reorganization and fusion process at sufficiently high temperatures. Author

Subject Categories:

  • Polymer Chemistry
  • Atomic and Molecular Physics and Spectroscopy
  • Solid State Physics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE