Photo-oxidation of polymers—II

Geuskens, Georges; Baeyens‐Volant, Danielle; Delaunois, G.; Vinh, Q. Lu; Piret, W.; David, Christiane

doi:10.1016/0014-3057(78)90052-6

Cited by 73 publications

(16 citation statements)

References 10 publications

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“…On the other hand, crosslinks are formed by recombination of macroradicals produced close together in reactions [1] and [2]. The quantum yield of crosslinking has been measured by GPC to be about 1O (3) in agreement with the mechanism proposed.…”

Section: Jjsupporting

confidence: 78%

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Recent advances in the photo-oxidation of polymers

Geuskens¹,

David²

1979

Pure and Applied Chemistry

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-Recent results, mainly selected from the authors work on polystyrene, clearly indicate that a sound understanding of the photo-oxidation of polymers cannot be gained without quantum yields determination. These show that transfer of energy has a major role in the initiation of the photo-oxidation because of the high local concentration of reactive groups in polymers. It is also possible to find correlations between the rate of ageing of industrial polymers and the extent of chemical transformation of the materials prior to the exposure to ultra-violet light.

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Section: Jjsupporting

confidence: 78%

“…We have indeed observed that hydrogen is evolved when polystyrene is irradiated under nitrogen at 254 nfl, probably as a consequence of reaction 12J W + CH -CH--* -CH --+ H [2] J a2…”

Section: Jjmentioning

confidence: 72%

Recent advances in the photo-oxidation of polymers

Geuskens¹,

David²

1979

Pure and Applied Chemistry

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“…Polystyrene alkyl radicals (R') formed during the initiation can easily react with molecular oxygen (triplet state), producing peroxy radicals by addition: R• + 02 ROO (10) The peroxy radicals ,obstract hydrogen -preferentially tertiary bonded -from other polystyrene molecules (R H) to form hydroperoxides and new polystyrene alkyl radicals (R'. ):…”

Section: Propagationmentioning

confidence: 99%

“…during exposure outdoors. The photo-oxidation of polystyrene has been extensively investigated by many authors (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15). The main reactions observed are bond scission, chain crosslinking and oxidative degradation.…”

Section: Introductionmentioning

confidence: 99%

New aspects of photodegradation and photooxidation of polystyrene

Rånby¹,

Lucki²

1980

Pure and Applied Chemistry

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-Polystyrene is degraded, oxidized and discolored when exposed to sunlight under atmospheric conditions. The chemical effects are ascribed to hydroperoxy, hydroxyl and carbonyl group formation. Chemical and spectroscopic data are not specific enough for identification of these different groups. Therefore, we have studied the photo-oxidation of the model compound 2-phenyl-butane. The resulting oxidized compounds have been separated and analyzed using a combined gas chromatograph-mass spectrometer. Mechanisms for the photo-oxidation of the model compounds have been proposed. By comparing these results with photooxidation data for polystyrene film, conclusions on the oxidation and degradation of the polymer have been outlined, including the carbonyl and hydroxyl group formation. The yellowing of the polymer is largely caused by phenyl ring opening reactions, for which probable mechanisms are suggested.

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“…absorption spectroscopy, continuously increases. This is due to energy transfer to hydroperoxide groups the concentration of which increases with time making the transfer of enegy progessively more efficient (23). Energy transfer from benzophenone or valerophenone to cumylhydroperoxide can also be demonstrated by phosphorescence measurements at 77°K in a methyltetrahydrofuran glass or in a polystyrene film (30) (31).…”

Section: The Free Radical Mechanism Of Oxidationmentioning

confidence: 99%

The Photo-Oxidation of Polymers. A Comparison With Low Molecular Weight Compounds

Geuskens¹,

David²

1979

Photochemistry–7

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-The photo-oxidation of polymers involves different steps in which their reactivity is different from that of low molecular weight conpounds. This is mainly due to the close vicinity of reactive groups in polymers and to the rigidity of the matrix. As a consequence, transfer of energy has a major role in the initiation of the photo-oxidation of most polymers on exposure to sunlight. It results in the sensitized decomposition of neighbouring hydroperoxide groups which, however, produce free radicals and thus initiate the oxidation less efficiently than model compounds in fluid solution. Scission of the polymer backbone, responsible for the alteration of the physical and mechanical properties, involves the decomposition of isolated hydroperoxide groups by two different mechanisms the relative importance of which changes with temperature.

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Photo-oxidation of polymers—II

Cited by 73 publications

References 10 publications

Recent advances in the photo-oxidation of polymers

Recent advances in the photo-oxidation of polymers

New aspects of photodegradation and photooxidation of polystyrene

The Photo-Oxidation of Polymers. A Comparison With Low Molecular Weight Compounds

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