Chemical kinetics on thermal decompositions of dicumyl peroxide studied by calorimetry

Duh, Yih-Shing; Chen-San, Kao; William, Lee Wen-Lian

doi:10.1007/s10973-016-5797-8

Cited by 23 publications

(5 citation statements)

References 29 publications

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“…The activation energy is associated to the amount of energy necessary to reach the optimum cure time, which is also associated to the amount of energy necessary to decompose the dicumylperoxide molecules as stated in the chemical equation i in Section 3.2 . Thus, the value of 115 kJ mol

is in accordance with the values reported in the literature [ 43 , 44 ] for DCP decomposition, and with the activation energy values that will be presented further in the crosslinking kinetics discussion. The exponent for the dicumylperoxide concentration has a negative value due to the decrease of the optimum cure time with the peroxide concentration and is less than 1 possibly due to its limitation in crosslinking the polymer, which will also be further explained.…”

Section: Resultssupporting

confidence: 89%

“…Duh et al [ 43 ] reported an activation energy for dicumylperoxide thermal decomposition of 110–150 kJ mol

, while Lv et al [ 44 ] reported values between 150 and 200 kJ mol

, which agree with the activation energy determined in the present study, i.e., varying between 85 and 140 kJ mol

.…”

Section: Resultssupporting

confidence: 89%

“…The curing rate is enhanced by temperature, as the cure curves, for all dicumylperoxide concentrations, become steeper for higher curing temperatures. Dicumylperoxide decomposition kinetics is favoured by temperature [ 43 , 44 ], leading to a faster crosslinking reaction for the PDMS/DCP systems as well. Crosslinking velocity is also promoted by higher concentrations of dicumylperoxide, due to the higher concentration of radicals and the autocatalytic nature of this process.…”

Section: Resultsmentioning

confidence: 99%

See 2 more Smart Citations

Peroxide-Based Crosslinking of Solid Silicone Rubber, Part I: Insights into the Influence of Dicumylperoxide Concentration on the Curing Kinetics and Thermodynamics Determined by a Rheological Approach

et al. 2022

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Predicting the curing behaviour of industrially employed elastomeric compounds under typical processing conditions in a reliable and scientifically driven way is important for rubber processing simulation routines, such as injection moulding. Herein, a rubber process analyser was employed to study the crosslinking kinetics of solid silicone rubber based on the concentration of dicumylperoxide. A model was proposed to describe the optimal cure time variation with peroxide concentration and temperature, based on the analysis of processing parameters applying kinetic and thermodynamic judgments. Additionally, the conversion rate was described with the aid of a phenomenological model, and the effect of dicumylperoxide concentration on the final crosslink state was investigated using kinetic and thermodynamic explanations. Optimal curing time was affected both by temperature and dicumylperoxide concentration. However, the effects were less pronounced for high temperatures (>170 ∘C) and high concentrations (>0.70 phr). A limit on the crosslink state was detected, meaning that the dicumylperoxide capacity to crosslink the silicone network is restricted by the curing mechanism. Curing restrictions were presumed to be primarily thermodynamic, based on the proton abstraction mechanism that drives the crosslinking reaction. In addition to providing more realistic crosslinking models for rubber injection moulding simulation routines, the results of this study may also explain the chemical behaviour of organic peroxides widely used for silicone crosslinking.

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Section: Resultssupporting

confidence: 89%

“…Duh et al [ 43 ] reported an activation energy for dicumylperoxide thermal decomposition of 110–150 kJ mol

, while Lv et al [ 44 ] reported values between 150 and 200 kJ mol

, which agree with the activation energy determined in the present study, i.e., varying between 85 and 140 kJ mol

.…”

Section: Resultssupporting

confidence: 89%

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Peroxide-Based Crosslinking of Solid Silicone Rubber, Part I: Insights into the Influence of Dicumylperoxide Concentration on the Curing Kinetics and Thermodynamics Determined by a Rheological Approach

et al. 2022

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“…Alkoxyl radicals play crucial roles in various fields of chemistry, such as autoxidation in chemical industry and DNA damage caused by intracellular lipid peroxidation. , Alkoxyl radicals can be generated through thermal decomposition and the Fenton reaction of peroxides. The photochemical generation of alkoxyl radicals from di- tert -butyl peroxide ( I ) has been frequently used in the initiation of radical reactions for organic synthesis.…”

Section: Introductionmentioning

confidence: 99%

Reactivity and Product Analysis of a Pair of Cumyloxyl and tert-Butoxyl Radicals Generated in Photolysis of tert-Butyl Cumyl Peroxide

Oyama

Abe

2020

J. Org. Chem.

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Alkoxyl radicals play important roles in various fields of chemistry. Understanding their reactivity is essential to applying their chemistry for industrial and biological purposes. Hydrogen-atom transfer and C−C β-scission reactions have been reported from alkoxyl radicals. The ratios of these two processes were investigated using cumyloxyl (CumO • ) and tert-butoxyl radicals (t-BuO • ), respectively. However, the products generated from the pair of radicals have not been investigated in detail. In this study, CumO • and t-BuO • were simultaneously generated from the photolysis of tert-butyl cumyl peroxide to understand the chemical behavior of the pair of radicals by analyzing the products and their distribution. Electron paramagnetic resonance and/or transient absorption spectroscopy analyses of radicals, including CumO • and t-BuO • , provide more information about the radicals generated during the photolysis of tert-butyl cumyl peroxide. Furthermore, the photoproducts of (3-(tert-butylperoxy)pentane-3yl)benzene demonstrated that the ether products were formed in in-cage reactions. The triplet-sensitized reaction induced by acetophenone, which is produced from CumO • , clarified that the spin state did not affect the product distribution.

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“…Photochemical decomposition of dicumyl peroxide and cumene hydroperoxide have been the subject of numerous studies in the past. − While both are known to decompose to the transient cumyloxy radical, the radical can theoretically decompose via two pathways: (i) to phenyl radical and acetone (eq ) or (ii) to acetophenone and a methyl radical (eq 6). …”

Section: Results and Discussionmentioning

confidence: 99%

Energy Landscapes in Photochemical Dissociation of Small Peroxides

et al. 2019

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Organic peroxides are known to have important roles in many chemical and biochemical processes such as intermediates in the oxidation of various hydrocarbons, as initiators of free-radical polymerization and cross-linking agents, etc. Consequently, the study of the organic peroxides and their radicals are of fundamental interest and importance. Although several reaction pathways after dissociation of organic peroxides have been successfully identified using time-resolved optical absorption spectroscopy, interpretation of the data can be complicated due to spectral overlap of parent molecules, intermediates, and products. Therefore, a reliable theoretical framework is necessary in case of complex or less studied systems. In this study, we investigated the plausible thermal dissociation pathways of diethyl peroxide, ditert butyl peroxide, and dicumyl peroxide by density functional theory with M06-2X hybrid functional and compared its results to coupled cluster single double and perturbative triple, CCSD(T), level energies. Our results indicate that methyl radical elimination is the main dissociation mechanism for all of the studied peroxides after O−O bond cleavage which has been also observed in experiments. The resulting relative energies of the M06-2X functional were found to have reasonable accuracy in comparison with the CCSD(T) method. We also show that time-dependent density functional theory (TD-DFT) with the M06-2X functional provides a suitable guide for interpretation of time-resolved optical absorption spectra of peroxides. The experimental transient absorption spectra of dicumyl peroxide are interpreted using the theoretically predicted pathways and transient radical species. Both results agree within experimental resolution and accuracy. We propose that the traditionally assigned visible absorption is not due to the cumuloxyl radical and the photodissociation of dicumyl peroxide involves other pathways with extremely short-lived radicals.

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Chemical kinetics on thermal decompositions of dicumyl peroxide studied by calorimetry

Cited by 23 publications

References 29 publications

Peroxide-Based Crosslinking of Solid Silicone Rubber, Part I: Insights into the Influence of Dicumylperoxide Concentration on the Curing Kinetics and Thermodynamics Determined by a Rheological Approach

Peroxide-Based Crosslinking of Solid Silicone Rubber, Part I: Insights into the Influence of Dicumylperoxide Concentration on the Curing Kinetics and Thermodynamics Determined by a Rheological Approach

Reactivity and Product Analysis of a Pair of Cumyloxyl and tert-Butoxyl Radicals Generated in Photolysis of tert-Butyl Cumyl Peroxide

Energy Landscapes in Photochemical Dissociation of Small Peroxides

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