Thermal degradation of polymers at high temperatures

Abstract

Work on thermal degradation of polymers has previously been carried out at temperatures up to about 500 °C. In the present work the range has been extended to 850 °C. Polystyrene was pyrolyzed in a vacuum and also in helium at atmospheric pressure at 362 °C and at 850 °C. Analysis of the volatile products indicates that higher temperatures and higher pressures cause a greater fragmentation of the volatile products. Samples of poly(vinylidene fluoride), polyacrylonitrile, and polytrivinylbenzene, were pyrolyzed in a vacuum at temperatures from 350 °C to 800 °C. The more volatile products were analyzed qualitatively and quantitatively in a mass spectrometer. The less volatile products were tested for their average molecular weight by a microcryoscopic method. Rates of thermal degradation were also determined for the last three polymers. The activation energies in the temperature range 218 °C to 440 °C were found to be 48, 31, and 73 kcal/mole, respectively, for poly(vinylidene fluoride), polyacrylonitrile, and polytrivinylbenzene.