Thermal degradation of vinyl polymers II—The synthesis and degradation of polystyrene containing thermally weak bonds

Richards, D. H.; Salter, David A.

doi:10.1016/0032-3861(67)90018-3

Cited by 27 publications

(8 citation statements)

References 11 publications

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“…Similarly, there are references in the literature which have confirmed the contribution of weak links in early decomposition in some plastics. Richards and Salter in their study evaluated thermal degradation of PS by using poly(α‐methylstyrene) as a radical producing agent and confirmed the contribution of these weak links in initiating the degradation at otherwise stable temperatures.…”

Section: Resultsmentioning

confidence: 87%

Temperature‐dependent pyrolytic product evolution profile for polyethylene terephthalate

Hujuri

Ghoshal

Gumma

2013

J of Applied Polymer Sci

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In this study, a detailed gas chromatographic study of pyrolysis products of polyethylene terephthalate (PET) has been carried out over a wide range of temperature (200-600 C). At low pyrolysis temperatures (200-300 C), yield of lighter hydrocarbons (C5-C10) is low; this gradually increases until maximum decomposition temperature (435 C) and decreases thereafter. At low temperature, PET essentially decomposes by ionic mechanism. However, at higher temperature, it may also proceed by radical mechanism. The following reaction types were considered to explain the decomposition mechanism of PET: (a) heterolytic (ionic) main-chain cleavage to form an olefin-end and an acid-end structure; (b) intra-or intermolecular ester-interchange reactions to yield cyclic oligomers; (c) intramolecular hydrogen transfer to form volatile products and regeneration of the acid-ends or, olefinends; (d) decarboxylation and intramolecular elimination of acetaldehyde, and acetylene; and (e) hydrogen abstraction and acetylene addition mechanism for the formation of polycyclic aromatic hydrocarbons.

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Section: Resultsmentioning

confidence: 87%

Temperature‐dependent pyrolytic product evolution profile for polyethylene terephthalate

Hujuri

Ghoshal

Gumma

2013

J of Applied Polymer Sci

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“…A recent major study [14,15,16] of the decomposition of polystyrene utilized poly (a-methylstyrene) [14] as catalyst for the polystyrene degradation, anionically '" prepared polystyrene with specifically formed thermolabile structures [15] and carbon 14 labeled polystyrene [16]. The results of this very extensive experimentation raise many points but the most interesting aspects are: (1) the confirmation of short zip lengths of approximately 3, (2) 1.2 intermolecular transfer steps per radical formed, (3) strong evidence for termination by combination with the possibility that the cage effect may tend to make termination kinetically first order.…”

Section: Introductionmentioning

confidence: 99%

Pyrolysis of anionic and thermally prepared polystyrenes

Wall¹,

Straus²,

Florin³

et al. 1973

J. RES. NATL. BUR. STAN. SECT. A.

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The changes in molecular weights, their distributions, and initial rates have been measured, for a series of polystyrenes prepared by thermal and anionic procedures. The information obtained and previous results can be explained to a very large extent by a kinetic chain decomposition comprised of competing end and random initiation, depropagation, intra-and intermolecular transfer and termination by combination.Key words: Anioni c polysl yre ne; molec ular weight distributions; molecular weights; thermal poly· s t yre :1 e; polymer ; pc ! ys t y !"e~e de g!"2da t!op. ; pyrolys is; thermolys is.

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“…At higher temperatures (600 and 700 • C), increased production of benzene, toluene, ethylbenzene, and α-methyl styrene and decreased production of styrene have been observed, probably due to the predominance of intramolecular hydrogen transfer reactions at this range of temperatures [18]. Concerning termination, some authors propose a mechanism involving the recombination [9,11], or the disproportionation reaction [19] between two radicals; while others suggest the occurrence of depropagation until the end of the polymer molecule [13].Published studies related to the thermal degradation and pyrolysis of polystyrene [13,[20][21][22][23][24][25] have been performed in a variety of reaction systems and sets of conditions, including reaction temperatures, reaction times, and molecular weights of the polystyrene sample, resulting in a broad collection of reaction yields and product distribution. The available reported experimental data fall into three types: chemical nature of the products (that help to elucidate the degradation mechanism), rate of evolution of products, and the change of molecular weight in the residue.Jellinek [22] reported experiments carried out in long open-to-air tubes containing 0.1 to 0.5 g of material, to show the influence of oxygen on the thermal degradation of polystyrene.…”

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confidence: 99%

Thermal Pyrolysis of Polystyrene Aided by a Nitroxide End-Functionality. Experiments and Modeling

2020

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The thermal pyrolysis of polystyrene (PS) is gaining importance as the social pressure for achieving a circular economy is growing; moreover, the recovery of styrene monomer in such a process is especially relevant. In this study, a simple thermal pyrolysis process in the temperature range of 390–450 °C is developed. A working hypothesis is that by using a nitroxide-end functionalized PS (PS-T or dormant polymer), the initiation process for the production of monomer (unzipping) during the PS pyrolysis could be enhanced due to the tendency of the PS-T to activate at the nitroxide end. Two types of PS were used in this work, the first one was synthesized by free-radical polymerization (FRP-dead polymer) and the second by nitroxide-mediated polymerization (NMP) using three levels of nitroxide to initiator ratio: 1.3, 1.1, and 0.9. Analysis of the recovered products of the pyrolysis by gas-mass spectroscopy shows that the yield of styrene increases from ∼33% in the case of dead polymer to ∼38.5% for PS-T. A kinetic and mathematical model for the pyrolysis of dead and dormant polymer is proposed and solved by the method of moments. After a parameter sensitivity study and data fitting, the model is capable of explaining the main experimental trends observed.

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Thermal degradation of vinyl polymers II—The synthesis and degradation of polystyrene containing thermally weak bonds

Cited by 27 publications

References 11 publications

Temperature‐dependent pyrolytic product evolution profile for polyethylene terephthalate

Temperature‐dependent pyrolytic product evolution profile for polyethylene terephthalate

Pyrolysis of anionic and thermally prepared polystyrenes

Thermal Pyrolysis of Polystyrene Aided by a Nitroxide End-Functionality. Experiments and Modeling

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