Accession Number : AD0447961


Title :   THERMAL DEGRADATION OF AN AROMATIC POLYPYROMELLITIMIDE IN AIR AND VACUUM. I. RATES AND ACTIVATION ENERGIES,


Corporate Author : JOHNS HOPKINS UNIV LAUREL MD APPLIED PHYSICS LAB


Personal Author(s) : Bruck, S D


Report Date : Oct 1963


Pagination or Media Count : 9


Abstract : The thermal degradation of a polypyromellitimide (condensation product of pyromellitic anhydride and an aromatic diamine) was studied in air and vacuum in the range 400 to 700 C by thermogravimetry using a recording electrobalance. Although this organic polymer is remarkably stable in air up to approximately 420 C, at temperatures in excess of this it begins to volatilize. At 485 C practically total volatilization takes place within approximately 5 hr. In vacuum, the polymer shows greater heat stability, with no appreciable weight loss even after prolonged exposure to temperatures up to approximately 500 C. Above this temperature it begins to volatilize, leaving a brittle, carbonized residue which appears to reach a limiting weight corresponding to approximately 45% of the original sample, and showing no infrared absorption bands. The rates of volatilization were calculated from the thermal degradation profiles. The Arrhenius relationship gave an activation energy of 32 kcal/mole and 74 kcal/mole for degradation in air and vacuum, respectively. (Author)


Descriptors :   *AROMATIC COMPOUNDS , DEGRADATION , POLYMERS , PYROLYSIS , STABILITY , VACUUM , HEAT OF ACTIVATION , INSTRUMENTATION , OXYGEN HETEROCYCLIC COMPOUNDS , EVAPORATION , INFRARED SPECTRA


Distribution Statement : APPROVED FOR PUBLIC RELEASE