Oxidation of crystalline polyethylene

Oluwoye, Ibukun; Altarawneh, Mohammednoor; Gore, Jeff; Dlugogorski, Bogdan Z.

doi:10.1016/j.combustflame.2015.07.007

Cited by 39 publications

(35 citation statements)

References 53 publications

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“…However, complementary to the low‐temperature oxidation by triplet oxygen, the presence of singlet O 2 can initiate photochemical or enhanced‐thermal reaction pathways. These classes of low‐temperature reaction have found practical applications in remediating organic pollutants in wastewater [31,148] and atmospheric degradation of the biogenic (naturally occurring) volatile organic compounds (BVOC), [232,234] as they are kinetically more favourable than some other oxidative channels [235–238] . Moreover, recent studies have shown the combustion application of singlet oxygen treating halogenated pollutants such as polychlorinated biphenyls (PCBs) polychlorinated dibenzodioxins (PCDDs) and furans (PCDFs) [239,240] .…”

Section: Implications Of Singlet Oxygen In Combustion and Advanced Oxmentioning

confidence: 99%

Review of Chemical Reactivity of Singlet Oxygen with Organic Fuels and Contaminants

Al-Nu’airat

Oluwoye

Zeinali

et al. 2020

The Chemical Record

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Singlet oxygen represents a form of reactive oxygen species (ROS), produced by electronic excitation of molecular triplet oxygen. In general, highly reactive oxygen‐bearing molecules remain the backbone of diverse ground‐breaking technologies, driving the waves of scientific development in environmental, biotechnology, materials, medical and defence sciences. Singlet oxygen has a relatively high energy of about 94 kJ/mol compared to the ground state molecular O2 and therefore initiates low‐temperature oxidation of electron‐rich hydrocarbons. Such reactivity of singlet oxygen has inspired a wide array of emerging applications in chemical, biochemical and combustion phenomena. This paper reviews the intrinsic properties of singlet oxygen, emphasising the physical aspects of its natural occurrences, production techniques, as well as chemical reactivity with organic fuels and contaminants. The review assembles critical scientific studies on the implications of singlet oxygen in initiating chemical reactions, identifying, and quantitating the consequential effects on combustion, fire safety, as well as on the low‐temperature treatment of organic wastes and contaminants. Moreover, the content of this review appraises computational efforts, such as DFT quantum mechanical modelling, in developing mechanistic (i. e., both thermodynamic and kinetic) insights into the reaction of singlet oxygen with hydrocarbons.

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Section: Implications Of Singlet Oxygen In Combustion and Advanced Oxmentioning

confidence: 99%

Review of Chemical Reactivity of Singlet Oxygen with Organic Fuels and Contaminants

Al-Nu’airat

Oluwoye

Zeinali

et al. 2020

The Chemical Record

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“…In the last decade, the idea of investigating the elementary mechanisms of PE degradation using ab initio calculations has emerged. Although kinetic constants and activation energies have been generally deduced from experiments by indirectly measuring the concentration of the products and assuming Arrhenius behaviour, there are reactions and processes which are difficult to probe experimentally such as H diffusion, abstraction, or parameters like transition ring size; the corresponding (free) energy barriers can be predicted by first principles calculations [ 28 , 29 , 30 , 31 , 32 , 33 ]. Especially, calculations have focused on the activation energy of reactions, because it crucially controls kinetic rate constants.…”

Section: Introductionmentioning

confidence: 99%

Atomic Scale Mechanisms Controlling the Oxidation of Polyethylene: A First Principles Study

2021

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Understanding the degradation mechanisms of aliphatic polymers by thermal oxidation and radio-oxidation is very important in order to assess their lifetime in a variety of industrial applications. We focus here on polyethylene as a prototypical aliphatic polymer. Kinetic models describing the time evolution of the concentration of chain defects and radicals species in the material identify a relevant step in the formation and subsequent decomposition of transient hydroperoxides species, finally leading to carbonyl defects, in particular ketones. In this paper, we first summarize the most relevant mechanistic paths proposed in the literature for hydroperoxide formation and decomposition and, second, revisit them using first principles calculations based on Density Functional Theory (DFT). Our results partially confirm commonly accepted reaction energies, but also propose alternative, more favourable, reaction paths. We highlight the influence of the environment—crystalline or not—on the outcome of some of the studied chemical reactions. A remarkable result of our calculations is that hydroxyl radicals play an important role in the decomposition of hydroperoxides. Based on our findings, it should be possible to improve the set of equations and parameters used in current kinetic simulations of polyethylene radio-oxidation.

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“…More oxidation is expected in XLPE samples in general when compared to LDPE samples based on its lower crystallinity, and explains the differences found there as well. [33] The averages of each of the three peaks were found to match up with each of the proposed origins. Observed energies for conduction and charge injection are around 1 eV, matching the average observed here.…”

Section: Tsdc Procedures and Parametersmentioning

confidence: 99%

“…More oxidation is expected in XLPE samples in general when compared to LDPE samples based on its lower crystallinity, and explains the differences found there as well. [ 33 ]…”

Section: Tsdc Spectra Of D‐xlpe and Degassed Ldpementioning

confidence: 99%

Thermally stimulated depolarization current spectra of cross‐linked polyethylene and the influence of cross‐linking byproducts

Walker

Hamedi

Woodward³

et al. 2020

Journal of Polymer Science

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Cross-linked polyethylene (XLPE) is notable for its use as power cable insulation. Its longevity is limited by space charge buildup linked to impurities such as the byproducts left behind by the cross-linking agent dicumyl peroxide (DCP). The goal of this work is to determine the impacts of these byproducts on charge trapping and detrapping in XLPE using the thermally stimulated depolarization current technique. XLPE with byproducts has one source of trapped charge, which originates from the byproducts. XLPE that was thermally treated via degassing exhibits two other sources of trapped charge, which are charge injection and dipolar relaxations. Oxidation from degassing was shown to control the trapping from these sources, which is useful knowledge for processing this material prior to its use. Reintroducing acetophenone, one of the major byproducts of DCP, suppresses those two peaks once more, showing that it controls the overall space charge buildup characteristics in XLPE.

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Oxidation of crystalline polyethylene

Cited by 39 publications

References 53 publications

Review of Chemical Reactivity of Singlet Oxygen with Organic Fuels and Contaminants

Review of Chemical Reactivity of Singlet Oxygen with Organic Fuels and Contaminants

Atomic Scale Mechanisms Controlling the Oxidation of Polyethylene: A First Principles Study

Thermally stimulated depolarization current spectra of cross‐linked polyethylene and the influence of cross‐linking byproducts

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