THERMAL DEGRADATION OF AN AROMATIC POLYPYROMELLITIMIDE IN AIR AND VACUUM: III. PYROLYTIC CONVERSION INTO A SEMICONDUCTOR,
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 g/cc. 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)
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 1964
- Accession Number
- AD0631831
Entities
People
- S. D. Bruck
Organizations
- Johns Hopkins University Applied Physics Laboratory