Kinetic studies on thermal decomposition of polystyrene peroxide

doi:10.1016/0165-2370(80)80015-5

Journal of Analytical and Applied Pyrolysis

Volume 1, Issue 4, May 1980, Pages 315-322

https://doi.org/10.1016/0165-2370(80)80015-5 Get rights and content

Abstract

Polystyrene peroxide has been synthesized and its decomposition has been studied by thermogravimetry and differential thermal analysis. Polystyrene peroxide has been found to decompose exothermically at about 110°C. The activation energy for the decomposition was estimated to be 30 kcal/mole both by the Jacobs and Kureishy method and by fitting the α versus time curves to the first-order kinetic equation. This suggests that the rate-controlling step in the decomposition of polystyrene peroxide is cleavage of the OO bond.

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Cited by (5)

Detailed mechanistic modeling of poly(styrene peroxide) pyrolysis using kinetic Monte Carlo simulation
2012, Chemical Engineering Science
Citation Excerpt :
The exothermic heat of degradation was thermodynamically calculated to be −50±1 kcal mol−1 (Kishore and Ravindran, 1982). The activation energy for PSP pyrolysis was calculated using DSC and thermogravimetric analysis (TGA) to be between 30 and 32.5 kcal mol−1 (Kishore et al., 1980), which is in agreement with reported values for the bond dissociation energy for peroxide bonds. In another study, a change in reaction order from 2 to 1 was observed during the degradation of PSP, which was attributed to the change in the rate controlling mechanism after a certain extent of decomposition (Kishore, 1981).
Conventional continuum mechanistic models for polymer degradation typically involve thousands of coupled differential-algebraic equations, requiring an efficient solver to solve the complex set of stiff model equations. This can be overcome by formulating the problem in terms of a stochastic simulation procedure, requiring only iterative operations to solve the model. The present work describes the detailed mechanistic modeling of pyrolysis of poly(styrene peroxide) (PSP) using kinetic Monte Carlo (KMC) simulation to predict the product yields and gain a better understanding of the product evolution pathways. The traditionally accepted mechanism of PSP pyrolysis proposed by Mayo and Miller, which involves the key reaction steps of peroxide bond fission, alkoxy radical recombination and disproportionation, and end chain β-scission, was initially tested using the KMC model to predict the peroxide concentration profile and the product yields. This model was only qualitatively able to predict the major products, benzaldehyde and formaldehyde, while the formation of minor products like α-hydroxy acetophenone, phenyl glycol, and phenyl glyoxal was not captured at all. Hence, a new mechanism that also incorporated hydrogen abstraction and β-scission was proposed and implemented in KMC. The final model tracked 949 reactions of 83 species. The rate coefficients for all the reaction steps were based on the existing literature reports, and hence no parameter estimation was done to fit the model against the experimental data. The revised model was quantitatively able to predict all the products of PSP pyrolysis, which was attributed to the stabilization of the alkoxy radicals by hydrogen abstraction, and the subsequent generation of additional alkoxy radicals by β-scission. KMC allowed the dominant pathways for the formation of minor products and dimers to be identified explicitly. Finally, the implications of this study in understanding the effect of trace peroxide bonds on poly(styrene) pyrolysis are outlined.
Effect of temperature, pressure and additives on pyrolysis of polystyrene peroxide
1983, Journal of Analytical and Applied Pyrolysis
Some aspects of the pyrolysis of polystyrene peroxide (PSP) have been examined. Low-temperature decomposition studies at 60°C and 70°C have been carried out to elucidate the ageing behaviour of PSP. The exothermic decomposition was found to be complete in 44 h at 70°C suggesting that all peroxide bonds have broken. Enthalpy measurements of the aged samples were carried out as a function of storage time. Ageing was also followed by infrared spectroscopy, and the intensity of the peroxide absorption around 1050 cm⁻¹ was found to decrease with ageing time. Benzaldehyde formed as a result of PSP pyrolysis is readily converted into benzoic acid, which crystallizes during the ageing process. Pyrolysis—gas chromatographic studies have shown that up to 450°C the basic decomposition mechanism (i.e., the formation of benzaldehyde and formaldehyde as the major products) does not change. No effect of pressure on the decomposition exotherm in differential thermal analysis was observed, suggesting that peroxide composition involves only condensed phase reactions. Hydroquinone, p-aminophenol and cadmium sulphide were found to retard the thermal decomposition of PSP, suggesting that these compounds would be potential antioxidants for polymers.
Thermal degradation of polystyrene-4. Decomposition of oxygen-containing polymers
1982, European Polymer Journal
The thermal decomposition of two polystyrene samples prepared by radical polymerisation in the presence of oxygen was studied in the temperature range 280–300°C where volatile formation is negligible. The energy of activation for chain scission of the oxygen-containing polymers was lower than that of a reference sample prepared under vacuum. All three polymers contained the same proportion of weak bonds and it was therefore concluded that these structures are not copolymerised peroxide groups.
Distribution changes during thermal degradation of poly(styrene peroxide) by pairing tree-based kinetic monte carlo and artificial intelligence tools
2021, Industrial and Engineering Chemistry Research
Physicochemical behaviour of polyperoxides
1991, Current Science

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Kinetic studies on thermal decomposition of polystyrene peroxide

Abstract

J. Amer. Chem. Soc.

J. Amer. Chem. Soc.

J. Amer. Chem. Soc.

Vysokomol. Soedin., Ser B

C.A.

J. Amer. Chem. Soc.