| Popis: |
The thermal vacuum degradation of typical polyhetero-arylenes, i.e. aromatic polyamides, polyimides, pyrrhones and polyphenylanthrolines, has been studied. The liveration of gas under isothermal heating conditions has been used to determine the degradation temperature of these polymers. The general principles governing the effects of bond isomerism, the type of “reinforcing” atoms and groups, of bulk groups present in the branches, and of the type of aromatic chain units present in the polymer on heat resistance have been analysed. The main factors determining the heat resistance of the polyhetero-arylenes are described, attention being given to the effects of molecular mobility of the segments, chain rigidity, and the state of phase. The main routes of hydro- and homolytic decompositions of the polyhetero-arylenes at high temperatures have been assessed. |
