Kinetic studies in the chemistry of rubber and related materials. II. The kinetics of oxidation of unconjugated olefins

Bolland, J. L.; Gee, Geoffrey

doi:10.1039/tf9464200236

Cited by 487 publications

(166 citation statements)

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“…[48,49] After the rate determining step of bond dissociation, radicals are formed that can react with themselves (leading to crosslinking or via disproportionation to the formation of C=C double bonds). However, in the presence of oxygen, the radicals readily react to form hydroperoxy compounds.…”

Section: Colour Measurementsmentioning

confidence: 99%

Contaminant release from aged microplastic

et al. 2017

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Environmental context. Increasing global plastic production adds plastic debris to the environment. We show that potentially harmful additives present in plastic particles are released to water at an increased rate when material properties change by aging due to exposure to high temperature and especially to UV radiation. For risk assessment of such plastic additives, more information on their degradation products and their toxicity is needed.Abstract. Recycled plastic granules of high-density polyethylene, polyvinyl chloride and polystyrene the size of microplastics were exposed to artificial aging conditions (2000 h; photooxidative and thermo-oxidative) to simulate their fate outdoors. Their potential to leach into water during the aging process was investigated using column percolation tests. Aging-related changes on the surface of the material were characterised by IR measurements indicating oxidation reactions with the formation of new adsorption bands (C=O, C-O and OH), especially in the case of photooxidative aging. These findings were confirmed by the identification of leachable organic compounds. Leaching of total organic carbon, Cl, Ca, Cu and Zn is clearly affected by changes due to aging, and their release is increased after photooxidative aging. In general, exposure to photooxidative conditions shows a greater influence on aging and thus on leaching and seems to be the more important mechanism for the aging of microplastic in the environment. Comparison with the total content of inorganic species revealed that, for most elements, less than 3% of the total content is released after 2000 h of photooxidative aging.

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Section: Colour Measurementsmentioning

confidence: 99%

Contaminant release from aged microplastic

et al. 2017

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“…10 the reciprocal rate of double bond consumption has been plotted against reciprocal O 2 pressure. When propagation occurs only by hydrogen abstraction, it has been demonstrated a long time ago [18] that under certain conditions (stationary state, no POOH decomposition, long kinetic chains, k 5 2 ¼ 4k 4 k 6 ) the dependence must be linear [19]. It has been shown many times, later, that this relationship remains linear even when the validity conditions are not obeyed, but this is the first time, to our knowledge that this relationship has been applied to a case of dual propagation, revealing its universality.…”

Section: Effect Of Oxygen Pressurementioning

confidence: 99%

Oxidation of unvulcanized, unstabilized polychloroprene: A kinetic study

Gac

Roux

Verdú

et al. 2014

Polymer Degradation and Stability

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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. Thermal oxidation in air at atmospheric pressure, in the 80e140 C temperature range and in oxygen at 100 C in the 0.02e3 MPa pressure range, of unvulcanized, unstabilized, unfilled polychloroprene (CR) has been characterized using FTIR and chlorine concentration measurement. The kinetic analysis was focused on double bond consumption. A mechanistic scheme involving unimolecular and bimolecular hydroperoxide decomposition, oxygen addition to alkyl radicals, hydrogen abstraction on allylic methylenes, alkyl and peroxyl additions to double bonds and terminations involving alkyl and peroxy radicals was elaborated. The corresponding rate constants were partly extracted from the literature and partly determined from experimental data using the kinetic model derived from the mechanistic scheme in an inverse approach. Among the specificities of polychloroprene, the following were revealed: The rate of double bond consumption is a hyperbolic function of oxygen pressure that allows a law previously established for the oxidation of saturated substrates to be generalized. CR oxidation is characterized by the absence of an induction period that reveals the instability of hydroperoxides. The kinetic analysis also reveals that peroxyl addition is faster than hydrogen abstraction but slower in CR than in common hydrocarbon polydienes.

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“…as enhancement factor, the definition of which is (31) where K£ and KL are the overall liquid phase mass transfer coefficients with and without chemical reaction respectively. t may also be expressed in terms of KG and KG if the gas phase resistance is considerable.…”

Section: Enhancement Factormentioning

confidence: 99%