Thermal decomposition (STA and DSC) of PVC compounds under a variety of atmospheres and heating rates

✍ Scribed by M.M. Hirschler

• Publisher: Elsevier Science
• Year: 1986
• Tongue: English
• Weight: 514 KB
• Volume: 22
• Category: Article
• ISSN: 0014-3057
• DOI: 10.1016/0014-3057(86)90111-4

✦ Synopsis

Simultaneous thermal analyses (thermogravimetric. differential thermogravimetric and differential thermal analyses) have been performed on Samples of five typical compounds based on poly(vinyt chloride). The analyses were performed at three heating rates and in atmospheres of nitrogen, air and oxygen. Differential scanning calorimetric analyses were additionally run on the same samples, in nitrogen. The materials used were a suspension-polymerised resin, a mass-polymerised resin, pipe material, wall covering material and wire jacketing material. All of them decompose in three main breakdown stages, the first accounting for over 60 wt% of the pure resins and for over 50 wt% of the other compounds. The values of T~ and T D have been determined under all conditions; T~.o is consistently less sensitive to these variations than T o. particularly for the manufactured compounds. By analysing both the STA and the DSC data, it has been possible to distinguish between a pure resin prepared by suspension polymerisation and one prepared by mass polymerisation. Kinetic analyses have been carried out on all the data to determine the activation parameters. The first of the three breakdown stages is actually a composite of two stages, suggesting that the dehydrochlorination (by chain-stripping) cannot be complete at the end of this composite first stage. Furthermore, this stage must also involve some C C bond scission, contrary to what has traditionally been assumed.