Infrared study of oxidation of elastomers

Field, J. E.; Woodford, D. E.; Gehman, S. D.

doi:10.1002/pol.1955.120157905

Cited by 18 publications

(2 citation statements)

References 13 publications

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“…This implies the participation of oxygen in the thermolysis and a different mechanism of degradation depending upon the atmosphere. A variety of C O and C-O chromophores have been detected in the infrared spectra of the oxidized PCP 19,20 and this agrees with the participation of oxygen in the degradation reaction.…”

Section: Polychloroprenesupporting

confidence: 60%

Thermal degradation of cross-linked polyisoprene and polychloroprene

Jiang

Levchik

et al. 2000

Polymer Degradation and Stability

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Polyisoprene and polychloroprene have been cross-linked either in solution or in solid state using free radical initiators. In the comparable experimental conditions higher cross-linking density was observed in the solid state process. Independent of the cross-linking method, polychloroprene tended to give a higher gel content and cross-link density than does polyisoprene. Infrared characterization of the cross-linked materials showed cis-trans isomerization occurred in the polyisoprene initiated by benzoyl peroxide, whereas no isomerization was found in the samples initiated by dicumyl peroxide. Polyisoprene does not cross-link by heating in a thermal analyzer, whereas polychloroprene easily undergoes cross-linking in such conditions. Infrared spectroscopy showed that in the case of polyisoprene, rearrangements occur upon heating which lead to the formation of terminal double bonds, while polychloroprene loses hydrogen chlorine which leads to a conjugated structure. There is apparently some enhancement of the thermal and thermal oxidative stability of polyisoprene because of the cross-linking. Cross-linked polychloroprene is less thermally stable than the virgin polymer. Cross-linking promotes polymers charring in the main step of weight loss in air, which leads to enhanced transitory char

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Section: Polychloroprenesupporting

confidence: 60%

Thermal degradation of cross-linked polyisoprene and polychloroprene

Jiang

Levchik

et al. 2000

Polymer Degradation and Stability

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“…Field et a1. 8 polymer that had absorbed 5% oxygen did not exhibit the presence of any oxygen-containing groups in its spectra. Therefore, one is tempted to infer that at 315°F.…”

Section: Mechanism Of Degradation During Hot Masticationmentioning

confidence: 92%

Mechanochemical degradation of an EPDM polymer

Baranwal¹

1968

J of Applied Polymer Sci

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SynopsisA mill-masticatmion study of an EPDM polymer (DuPont, Nordel 1070) was conducted in the mill-roll bmperature range of 68-480'F. The extent of degradation was determined by dilute-solution viscosity measurements. The role of oxygen in the polymer mastication was followed by infrared spectroscopy. The breakdown of the EPDM polymer on the mill is minimum in the temperature range of 185-315'F. Up to 315°F. the increase in temperature leads to a decreased amount of degradation. During cold mastication mechanical breakdown occurs. The use of a free-radical acceptor shows that this type of breakdown is caused by the mechanical rupture of C-C bonds in the polymer chain. At and above 350°F. thermooxidative degradation becomes dominant, the polymer degrading drastically, and the higher the temperature, the greater the extent of degradat,ion for the same period of mastication. Infrared spectroscopy shows that hot mastication results in decreased double-bond concentration and increased amounts of carbonyl and, possibly, anhydride and lactone groups. Of the carbonyl groups formed 30% are due to the oxidation of double bonds in terpolymer and 70% to the oxidat-ion of the main chain. A mechanism is proposed to account for these observations.

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Examination of the oxidative degradation of polyacrylonitrile using infrared spectroscopy

Conley

Bieron

1963

J of Applied Polymer Sci

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The oxidative thermal degradation of polyacrylonitrile has been examined using infrared spectroscopy. It was found that the generally accepted mechanism for the thermal degradation of polyacrylonitrile in air, which involves direct interaction of neighboring nitrile groups, and alternate proposals, involving azomethine crosslinks through reaction of the nitrile group and a neighboring tertiary hydrogen atom, do not satisfactorily represent an initial degradation scheme accounting for the observed infrared spectral changes. Rather, it must be concluded that these reactions take place after the initial degradation, to produce highly complex pyridinoid systems, and are not observable under the experimental conditions employed here. By detailed interpretation of the spectral changes using, in part, a difference spectral examination technique, an alternate route for the oxidative degradation involving the introduction of double bonds in the polymer chain could be formulated. This reaction can best be visualized as occurring via the attack of molecular oxygen at the activated tertiary carbon–hydrogen bond adjacent to the electron‐withdrawing nitrile group. The nitrile group was shown to remain unreacted during the course of the initial oxidation. After the introduction of the double bond, a number of secondary degradative reactions, of which the previously proposed routes of degradation are representative, take place; these include degradation reactions of the nitrile groups to form acid and amide groups. It was observed that the accumulation of oxygenated intermediates on the surface of the polymer film is a rapid reaction and that the initial degradation process is controlled by the concentration of these species.

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Infrared study of oxidation of elastomers

Cited by 18 publications

References 13 publications

Thermal degradation of cross-linked polyisoprene and polychloroprene

Thermal degradation of cross-linked polyisoprene and polychloroprene

Mechanochemical degradation of an EPDM polymer

Examination of the oxidative degradation of polyacrylonitrile using infrared spectroscopy

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