“Close loop” mechanistic schemes for hydrocarbon polymer oxidation

Audouin, L.; Gueguen, Virginie; Tcharkhtchi, Abbas; Verdú, J.

doi:10.1002/pola.1995.080330605

Cited by 108 publications

(82 citation statements)

References 16 publications

(1 reference statement)

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“…Among these reaction steps, the hydroperoxide decompositions (IV) and/or (V) are the rate-determining steps [4,20,21]. The Es obtained here corresponds to those of the hydroperoxide decomposition [20].…”

Section: Resultsmentioning

confidence: 72%

“…The fall of E suggests that the existence of unsaturated chain end groups affects the reaction mechanism of iPP degradation. There is much literature on the mechanisms of the iPP autoxidation process [1][2][3][4][5]20]. Many researchers agree fundamentally with the following mechanistic scheme.…”

Section: Resultsmentioning

confidence: 99%

“…The reaction mechanism of the degradation has been recognized as a free-radical chain reaction, leading to polymer chain scission [1][2][3][4][5]. This radical reaction is a cyclic reaction and is called 'autoxidation'.…”

Section: Introductionmentioning

confidence: 99%

“…However, iPP easily undergoes oxidative degradation under the influence of elevated temperature and sunlight, and the degradation leads to a deterioration of the mechanical properties and yellowing [1][2][3][4][5].…”

Section: Introductionmentioning

confidence: 99%

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Degradation behavior of polymer blend of isotactic polypropylenes with and without unsaturated chain end group

Nakatani

Kurniawan

Taniike

et al. 2008

Science and Technology of Advanced Materials

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In this work, the relationship between the unsaturated chain end group content and the thermal oxidative degradation rate was systematically studied with binary polymer blends of isotactic polypropylene (iPP) with and without the unsaturated chain end group. The iPPs with and without the unsaturated chain end group were synthesized by a metallocene catalyst in the absence of hydrogen and by a Ziegler catalyst in the presence of one, respectively. The thermal oxidative degradation rate of the binary iPP blends was estimated from the molecular weight and the apparent activation energy ( E), which were obtained through size exclusion chromatography (SEC) and thermogravimetric analysis (TGA) measurements, respectively. These values exhibited a negative correlation against the mole content of the unsaturated chain end group. The thermal oxidative degradation rate apparently depends on the content of the unsaturated chain end group. This tendency suggests that the unsaturated chain end acts as a radical initiator of the iPP degradation reaction.

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Section: Resultsmentioning

confidence: 72%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Degradation behavior of polymer blend of isotactic polypropylenes with and without unsaturated chain end group

Nakatani

Kurniawan

Taniike

et al. 2008

Science and Technology of Advanced Materials

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“…Nevertheless, we can assume that PLA thermal oxidative degradation follows the mechanism shown in Figure 2. This hypothesis is made considering that the tertiary CH bond shows the lowest dissociation energy and that hydroperoxides (POOH) contribute mainly to the oxidation initiation step and follow a close-loop mechanism [26]. To complete this mechanism, we have to consider that the structure of the PO° radical can decompose by three possible -scissions as shown in Figure 3.…”

Section: ) Ageing Conditionsmentioning

confidence: 99%

Oxidative degradation of polylactide (PLA) and its effects on physical and mechanical properties

Rasselet¹,

Ruellan²,

Guinault³

et al. 2014

European Polymer Journal

124

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is an open access repository that collects the work of Arts et Métiers ParisTech researchers and makes it freely available over the web where possible. AbstractThe thermo-oxidative degradation of polylactide (PLA) films was studied between 70 and 150°C. It was shown that the oxidative degradation of PLA leads to a random chain scission responsible for a reduction of the molar mass. These molar mass changes affect Tg and the degree of crystalllinity, and it was found that Tg decreases according to the Fox-Flory theory whereas the degree of crystalllinity increases due to a chemicrystallization process. A correlation between molar mass and strain at break during oxidation has been established:PLA displays a brittle behaviour when M n falls below 40 kg.mol -1 in agreement with relationships linking the critical value for embrittlement with the molar mass between entanglements.

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Aging of Organic Matrix Composite Materials

Colin

Verdú

2011

Wiley Encyclopedia of Composites

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This article deals with aging mechanisms and kinetics in organic matrix composites, focusing on water‐polymer (humid aging) and oxygen‐polymer (thermo‐oxidative aging) interactions. The first section is devoted to problems common to all kinds of chemical aging, with emphasis on specific aspects of composite materials, for instance, role of interphase/interface in aging processes or anisotropy of water or oxygen diffusion in fiber‐reinforced materials. The effects of mechanical loading on diffusion kinetics and the diffusion‐reaction coupling are briefly evoked. The second section deals with humid aging. It is important to distinguish physical processes linked to plasticization and swelling of the polymer matrix by water and chemical (hydrolytic) aging, an ionic step‐by‐step reaction, which affects only polycondensates, especially polyesters. Hydrolysis induces random chain scission responsible for embrittlement and sometimes osmotic cracking responsible for blistering of the glass fiber‐polyester composites. The third section concerns thermo‐oxidative aging that results from a branched radical chain reaction. This kind of aging occurs when the material is exposed to high temperatures during its processing or in its use conditions, which is the case of many aerospace applications. The basics of nonempirical kinetic modeling are presented. The last section deals with the consequences of thermo‐oxidation on the thermomechanical properties including glass transition temperature, elastic properties, and fracture properties.

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“Close loop” mechanistic schemes for hydrocarbon polymer oxidation

Cited by 108 publications

References 16 publications

Degradation behavior of polymer blend of isotactic polypropylenes with and without unsaturated chain end group

Degradation behavior of polymer blend of isotactic polypropylenes with and without unsaturated chain end group

Oxidative degradation of polylactide (PLA) and its effects on physical and mechanical properties

Aging of Organic Matrix Composite Materials

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