Experimental study reveals annealing forms long polyenes without altering thermal stability in mass PVC, suggesting polymer morphology dictates degradation rates.
Mass polymerised poly(vinyl chloride) (PVC), subjected to annealing treatment between 85–140°C under air, nitrogen, vacuum, and hydrogen chloride environment, was found to undergo very slight decomposition in which long polyenes (with more than ten conjugated carbon‐carbon double bonds) were produced. Despite the presence of these polyenes the thermal stability of the resin at 190°C remained unaltered. Resin stability was also unaffected by the atmosphere in which the resin was annealed. By contrast, urea clathrate PVC, known to be highly crystalline, decomposed 300% faster than mass PVC and generated very long polyene sequences (n ≥ 42) at 190°C. The results are discussed in terms of two possible morphological populations of polymer.
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Gerrard et al. (1984) studied this question.
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