The effect of metal acetylacetonates on the thermal degradation of poly(methyl methacrylate)-I. Cobalt (III) acetylacetonate

I. C. McNeill, J. J. Liggat

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Abstract

Poly(methyl methacrylate) (PMMA), when pure, degrades quantitatively to monomer. Samples made by the free radical route decompose in two stages under programmed heating, the lower temperature reaction being initiated at unsaturated chain ends, and the higher temperature reaction by random scission of the backbone. The effect of small amounts of cobalt (III) acetylacetonate (Co(acac)3) on the thermal decomposition in the absence of air has been studied over the composition range from 1 : 400 to 1 : 10 metal chelate: monomer units. Even small amounts of Co(acac)3 have a profound effect on the thermal stability of PMMA. Several stages of decomposition are observed, which have been investigated by thermal volatilisation analysis, with detailed examination of the various product fractions. The main effects of the additive result from complex formation with the unsaturated chain ends and from attack of acetylacetonate radicals on the polymer, leading to some low temperature evolution of monomer, but also to stabilisation of the PMMA in the normal temperature region for decomposition as a result of the formation of some anhydride rings. Small amounts of products other than monomer are evolved. Mechanisms are discussed.

LanguageEnglish
Pages93-108
Number of pages16
JournalPolymer Degradation and Stability
Volume29
Issue number1
DOIs
Publication statusPublished - 1 Jan 1990

Fingerprint

thermal degradation
Polymethyl Methacrylate
Cobalt
Polymethyl methacrylates
polymethyl methacrylate
Pyrolysis
cobalt
monomers
Monomers
Metals
metals
Decomposition
decomposition
Temperature
vaporizing
Anhydrides
anhydrides
products
Free radicals
Vaporization

Keywords

  • cobalt compounds
  • plastics blends
  • polymers--thermal effects
  • polymethyl methacrylates

Cite this

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abstract = "Poly(methyl methacrylate) (PMMA), when pure, degrades quantitatively to monomer. Samples made by the free radical route decompose in two stages under programmed heating, the lower temperature reaction being initiated at unsaturated chain ends, and the higher temperature reaction by random scission of the backbone. The effect of small amounts of cobalt (III) acetylacetonate (Co(acac)3) on the thermal decomposition in the absence of air has been studied over the composition range from 1 : 400 to 1 : 10 metal chelate: monomer units. Even small amounts of Co(acac)3 have a profound effect on the thermal stability of PMMA. Several stages of decomposition are observed, which have been investigated by thermal volatilisation analysis, with detailed examination of the various product fractions. The main effects of the additive result from complex formation with the unsaturated chain ends and from attack of acetylacetonate radicals on the polymer, leading to some low temperature evolution of monomer, but also to stabilisation of the PMMA in the normal temperature region for decomposition as a result of the formation of some anhydride rings. Small amounts of products other than monomer are evolved. Mechanisms are discussed.",
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AU - Liggat, J. J.

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Y1 - 1990/1/1

N2 - Poly(methyl methacrylate) (PMMA), when pure, degrades quantitatively to monomer. Samples made by the free radical route decompose in two stages under programmed heating, the lower temperature reaction being initiated at unsaturated chain ends, and the higher temperature reaction by random scission of the backbone. The effect of small amounts of cobalt (III) acetylacetonate (Co(acac)3) on the thermal decomposition in the absence of air has been studied over the composition range from 1 : 400 to 1 : 10 metal chelate: monomer units. Even small amounts of Co(acac)3 have a profound effect on the thermal stability of PMMA. Several stages of decomposition are observed, which have been investigated by thermal volatilisation analysis, with detailed examination of the various product fractions. The main effects of the additive result from complex formation with the unsaturated chain ends and from attack of acetylacetonate radicals on the polymer, leading to some low temperature evolution of monomer, but also to stabilisation of the PMMA in the normal temperature region for decomposition as a result of the formation of some anhydride rings. Small amounts of products other than monomer are evolved. Mechanisms are discussed.

AB - Poly(methyl methacrylate) (PMMA), when pure, degrades quantitatively to monomer. Samples made by the free radical route decompose in two stages under programmed heating, the lower temperature reaction being initiated at unsaturated chain ends, and the higher temperature reaction by random scission of the backbone. The effect of small amounts of cobalt (III) acetylacetonate (Co(acac)3) on the thermal decomposition in the absence of air has been studied over the composition range from 1 : 400 to 1 : 10 metal chelate: monomer units. Even small amounts of Co(acac)3 have a profound effect on the thermal stability of PMMA. Several stages of decomposition are observed, which have been investigated by thermal volatilisation analysis, with detailed examination of the various product fractions. The main effects of the additive result from complex formation with the unsaturated chain ends and from attack of acetylacetonate radicals on the polymer, leading to some low temperature evolution of monomer, but also to stabilisation of the PMMA in the normal temperature region for decomposition as a result of the formation of some anhydride rings. Small amounts of products other than monomer are evolved. Mechanisms are discussed.

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