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

2003 ◽  
Vol 76 (3) ◽  
pp. 592-693 ◽  
Author(s):  
Prasenjeet Ghosh ◽  
Santhoji Katare ◽  
Priyan Patkar ◽  
James M. Caruthers ◽  
Venkat Venkatasubramanian ◽  
...  
Keyword(s):  
Kinetic Model ◽  
Natural Rubber ◽  
Reaction Mechanisms ◽  
Population Balance ◽  
Balance Model ◽  
Population Balance Model ◽  
Wide Range ◽  
Sulfur Vulcanization ◽  
Vulcanization Process ◽  
Single Set

Abstract 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.

POPULATION BALANCE MODEL FOR VULCANIZATION OF NATURAL RUBBER WITH DELAYED-ACTION ACCELERATOR AND PREVULCANIZATION INHIBITOR

2012 ◽  
Vol 85 (2) ◽  
pp. 219-243 ◽  
Author(s):  
M Anandhan ◽  
Niket S Kaisare ◽  
K Kannan ◽  
Bijo Varkey
Keyword(s):  
Natural Rubber ◽  
Reaction Mechanisms ◽  
Crosslink Density ◽  
Reaction Path ◽  
Population Balance ◽  
Equation Model ◽  
Balance Model ◽  
Curing Process ◽  
Major Species ◽  
Vulcanization Process

Abstract Our objective is to extend the population balance equation model for vulcanization of natural rubber in the presence of N-t-butylbenzothiazole-2-sulfenamide (TBBS) as an accelerator and N-(cyclohexylthio)phthalimide (CTP) as a retarder. The experiments performed by using the oscillating disk rheometer are used to track the evolution of crosslink density in natural rubber. The model quantitatively predicts the trends observed in the vulcanization mixture at various temperatures, including capturing the effects of changing the initial amounts of TBBS and CTP. This model is able to capture all the key trends involved in the retarder chemistry. Specifically, both experiments and model show that addition of CTP delays the scorching time by a few minutes, without affecting the final crosslink concentration. The model qualitatively predicts trends in the major species reported in the literature. The model can reliably predict and explain the trends of monosulfidic, disulfidic, and polysulfidic crosslinks in a conventional and efficient TBBS-accelerated system. Finally, reaction path analysis is performed for the vulcanization process, which is able to clearly identify the key reaction mechanisms in the induction, crosslinking, and postcrosslink zones during the curing process.

Activators in Accelerated Sulfur Vulcanization

2004 ◽  
Vol 77 (3) ◽  
pp. 512-541 ◽  
Author(s):  
Geert Heideman ◽  
Rabin N. Datta ◽  
Jacques W. M. Noordermeer ◽  
Ben van Baarle
Keyword(s):  
Reaction Mechanisms ◽  
Model Compound ◽  
Background Information ◽  
Zinc Compounds ◽  
Chemical Mechanisms ◽  
Sulfur Vulcanization ◽  
Multifunctional Additives ◽  
Vulcanization Process

Abstract This review provides relevant background information about the vulcanization process, as well as the chemistry of thiuram- and sulfenamide-accelerated sulfur vulcanization with emphasis on the role of activators, to lay a base for further research. It commences with an introduction of sulfur vulcanization and a summary of the reaction mechanisms as described in literature, followed by the role of activators, particularly ZnO. The various possibilities to reduce ZnO levels in rubber compounding, that have been proposed in literature, are reviewed. A totally different approach to reduce ZnO is described in the paragraphs about the various possible roles of multifunctional additives (MFA) in rubber vulcanization. Another paragraph is dedicated to the role of amines in rubber vulcanization, in order to provide some insight in the underlying chemical mechanisms of MFA systems. Furthermore, an overview of Model Compound Vulcanization (MCV) with respect to different models and activator/accelerator systems is given. In the last part of this review, the various functions of ZnO in rubber are summarized. It clearly reveals that the role of ZnO and zinc compounds is very complex and still deserves further clarification.

scholarly journals Study on the regional characteristics during foam flooding by population balance model

2020 ◽  
pp. 014459872098361
Author(s):  
Zhongbao Wu ◽  
Qingjun Du ◽  
Bei Wei ◽  
Jian Hou
Keyword(s):  
Numerical Simulation ◽  
Simulation Model ◽  
Oil Recovery ◽  
Population Balance ◽  
Growth Zone ◽  
Balance Model ◽  
Population Balance Model ◽  
Liquid Ratio ◽  
One Dimensional ◽  
Foam Flooding

Foam flooding is an effective method for enhancing oil recovery in high water-cut reservoirs and unconventional reservoirs. It is a dynamic process that includes foam generation and coalescence when foam flows through porous media. In this study, a foam flooding simulation model was established based on the population balance model. The stabilizing effect of the polymer and the coalescence characteristics when foam encounters oil were considered. The numerical simulation model was fitted and verified through a one-dimensional displacement experiment. The pressure difference across the sand pack in single foam flooding and polymer-enhanced foam flooding both agree well with the simulation results. Based on the numerical simulation, the foam distribution characteristics in different cases were studied. The results show that there are three zones during foam flooding: the foam growth zone, stable zone, and decay zone. These characteristics are mainly influenced by the adsorption of surfactant, the gas–liquid ratio, the injection rate, and the injection scheme. The oil recovery of polymer-enhanced foam flooding is estimated to be 5.85% more than that of single foam flooding. Moreover, the growth zone and decay zone in three dimensions are considerably wider than in the one-dimensional model. In addition, the slug volume influences the oil recovery the most in the foam enhanced foam flooding, followed by the oil viscosity and gas-liquid ratio. The established model can describe the dynamic change process of foam, and can thus track the foam distribution underground and aid in optimization of the injection strategies during foam flooding.

Population balance model for solid state sintering II. Grain growth

2001 ◽  
Vol 27 (1) ◽  
pp. 63-71 ◽  
Author(s):  
S Sivakumar ◽  
Manjunath Subbanna ◽  
Satyam S Sahay ◽  
Vijay Ramakrishnan ◽  
P.C Kapur ◽  
...  
Keyword(s):  
Solid State ◽  
Grain Growth ◽  
Population Balance ◽  
Balance Model ◽  
Population Balance Model ◽  
Solid State Sintering
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