On the mechanism of sulfur behavior in rubber compounds

Jurkowski, B.; Jurkowska, Barbara

doi:10.1080/00222349808220461

Cited by 18 publications

(30 citation statements)

References 11 publications

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“…In summary, several reaction schemes that lead to the formation of MBTS from MBS, as well as a series of exchange reactions that lead to MBTPs have been proposed. The reaction of MBTS with elemental sulfur, as will be discussed subsequently can also produce MBTPs; thus, the presence of MBTPs as shown in Figure 4 does not necessarily require the occurrence of exchange reactions R.12, R. 13 47,52 (R. 17) Although the unsymmetrical cleavage as shown below is also possible, it is not as likely, since it requires breaking of the more stable C-S bond.…”

Section: Sulfur Vulcanizaton Of Natural Rubber For Benzothiazole 603mentioning

confidence: 99%

“…Several kinetic models have been proposed that address limited aspects of the underlying chemistry and physics, but do not acknowledge all the mechanistic details of vulcanization given in Figure 1. Jurkowska and Jurkoswski 17 propose that vulcanization chemistry may be modeled by a set of nine reactions, which includes formation, rearrangement, transformation and degradation of the different crosslinks. However, their set of reactions does not describe the initial accelerator chemistry or the crosslinking chemistry; rather, they only describe the evolution of the polysulfidic crosslinks that are already formed.…”

Section: B Empirical and Other Limited Kinetic Modelsmentioning

confidence: 99%

“…However, polysulfidic crosslinks are thermally labile and may degrade into dead ends. The differential balance on monosulfides is therefore: (17) whereas for polysulfides, the PBE is: The PBEs for the accelerator-terminated polysulfidic radicals E * x will now be developed. These radicals are formed in R.42 by precursor fragmentation and R.53 by persulfenyl radical quenching; and, the radicals are consumed in R.16 by radical recombination, in R.19 by pickingup S 8 , and in R.49 by reacting with allylic hydrogen in rubber to give crosslink precursors.…”

mentioning

confidence: 99%

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Sulfur Vulcanization of Natural Rubber for Benzothiazole Accelerated Formulations: From Reaction Mechanisms to a Rational Kinetic Model

Ghosh

Katare

Patkar

et al. 2003

Rubber Chemistry and Technology

211

228

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The chemistry of accelerated sulfur vulcanization is reviewed and a fundamental kinetic model for the vulcanization process is developed. The vulcanization of natural rubber by the benzothiazolesulfenamide class of accelerators is studied, where 2-(morpholinothio) benzothiazole (MBS) has been chosen as the representative accelerator. The reaction mechanisms that have been proposed for the different steps in vulcanization chemistry are critically evaluated with the objective of developing a holistic description of the governing chemistry, where the mechanisms are consistent for all reaction steps in the vulcanization process. A fundamental kinetic model has been developed for accelerated sulfur vulcanization, using population balance methods that explicitly acknowledge the polysulfidic nature of the crosslinks and various reactive intermediates. The kinetic model can accurately describe the complete cure response including the scorch delay, curing and the reversion for a wide range of compositions, using a single set of rate constants. In addition, the concentration profiles of all the reaction intermediates as a function of polysulfidic lengths are predicted. This detailed information obtained from the population balance model is used to critically examine various mechanisms that have been proposed to describe accelerated sulfur vulcanization. The population balance model provides a quantitative framework for explicitly incorporating mechanistically reasonable chemistry of the vulcanization process.

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Section: Sulfur Vulcanizaton Of Natural Rubber For Benzothiazole 603mentioning

confidence: 99%

Section: B Empirical and Other Limited Kinetic Modelsmentioning

confidence: 99%

mentioning

confidence: 99%

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Sulfur Vulcanization of Natural Rubber for Benzothiazole Accelerated Formulations: From Reaction Mechanisms to a Rational Kinetic Model

Ghosh

Katare

Patkar

et al. 2003

Rubber Chemistry and Technology

211

228

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“…That is, if the amount of certain component in vulcanization formulation is changed, the fitted parameters no longer apply, since the concentrations of individual components are not directly incorporated into the model. Consequently, Monte-Carlo simulations, [4] reaction schemes [5][6][7][8][9][10][11][12][13] and mechanistic models were developed in an attempt to treat a variety of species present in vulcanization compound individually. The first and the most widely recognized reaction scheme was proposed by Coran.…”

Section: Introductionmentioning

confidence: 99%

Modeling the Vulcanization of Rubber Blends

Likozar

Krajnc

2006

Macromolecular Symposia

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Summary: Kinetics and heat transfer during vulcanization of various blends of polybutadiene (BR) and polyisoprene (NR) were studied simultaneously using mechanistic approach for description of reaction kinetics. Fourier transform infrared spectroscopy (FTIR) was used to study the kinetics of accelerator and retarder chemistry. Differential scanning calorimetry (DSC) and dynamic rheometry were applied in order to retrieve the data for heat transfer modeling during induction period and kinetic modeling throughout the process. Model reaction scheme was based on one of the best possible proposed individual reaction mechanisms. Molecular modeling was applied to differentiate between the reactions of chemically similar species. Physical and chemical model parameters were calculated from the experimental data. A minimum of average rubber heat transfer coefficient was found to be at equal BR and NR weight fractions in the blend while activation energies of crosslinking and reversion reactions increased linearly with increasing BR weight fraction.

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“…During the last 20 years, it is the polymer blends that have been very popular as a new group of polymer materials with interesting and sometimes very specific properties [1][2][3]. The reason for polymer blends manufacturing is the will to eliminate or to diminish the drawbacks that characterize the polymers and also desire to drop the price of the expensive polymers with specific properties by mixing them with the cheaper ones, without significant deterioration in these precious properties.…”

Section: Introductionmentioning

confidence: 99%