The thermal degradation of poly(methyl vinyl ketone) and poly(methyl isopropenyl ketone)

✍ Scribed by I.C. McNeill; D. Neil

• Publisher: Elsevier Science
• Year: 1971
• Tongue: English
• Weight: 630 KB
• Volume: 7
• Category: Article
• ISSN: 0014-3057
• DOI: 10.1016/0014-3057(71)90123-6

✦ Synopsis

The degradations have been studied by thermal volatilization analysis and thermogravimetry, with infrared and ultraviolet spectroscopic investigations of products. Under temperatureprogrammed heating conditions, PMVK first splits out water from adjacent side groups by a random process, giving a fused ring system as the first formed product. As the temperature is raised, chain scission occurs, leading eventually to a total weight loss as great as 90 per cent. This scission process appears to involve fission of bonds between adjacent ring structures, rather than breakdown of the rings themselves; it is accompanied by the production of small amounts of methane and carbon monoxide. The residue remaining above 500 ° is stable to temperatures greater than 800 ° , and is presumably a form of carbon.

The thermal decomposition of PMIK, under the same conditions, is superficially similar, although some differences in behaviour are also apparent. Monomer production occurs in PMIK, proceeding concurrently with the early stages of the coloration reaction. The yield of monomer is prevented from attaining 100 per cent by the cyclisation process, since the formation of the six membered rings greatly reduces the kinetic chain length of depulymerization. The large amount of methane and carbon monoxide evolved in the later stages of the decomposition of PMIK can be taken as an indication that cyclisation in this polymer is less efficient than in PMVK. A steric interpretation for this factor has been advanced.