Effect of CMCS on Vulcanization Kinetics of Natural Rubber

2012 ◽  
Vol 535-537 ◽  
pp. 1214-1217
Author(s):  
Yong Zhou Wang ◽  
Hong Xing Gui ◽  
Tao Chen ◽  
Hong Hai Huang ◽  
Fu Quan Zhang ◽  
...  
Keyword(s):  
Activation Energy ◽  
Natural Rubber ◽  
Induction Period ◽  
Rate Constants ◽  
Carboxymethyl Chitosan ◽  
Curing Period ◽  
Vulcanization Kinetics ◽  
Kinetics Of ◽  
Work Effect

In this work, effect of carboxymethyl chitosan (CMCS) on vulcanization kinetics of natural rubber was studied using the Rheometer MDR2000.The results showed that both the rate constants of induction period and curing period of natural rubber (K-N) was greater than that of natural rubber added CMCS and the dosage is 0.05% of fresh latex (CMCS-1), but less than that of natural rubber added CMCS and the dosage is 0.1% of fresh latex (CMCS-2), and the activation energy 100.8kJ/mol of induction period of K-N is greater than the activation energy 96.7kJ/mol, 93.7kJ/mol of induction period of CMCS-1, CMCS-2, respectively and that the activation energy 104.4 kJ/mol of curing period of K-N is less than the activation energy111.9kJ/mol of curing period of CMCS-1, and bigger than the activation energy 103.4 of CMCS-2 at the same temperature.

Vulcanization Kinetics of Starch Xanthate /Natural Rubber Composite

2013 ◽  
Vol 690-693 ◽  
pp. 363-367 ◽  
Author(s):  
Wen Jie Luo ◽  
Si Dong Li ◽  
Zhi Fen Wang ◽  
Lin Fang ◽  
Hua Lin ◽  
...  
Keyword(s):  
Activation Energy ◽  
Natural Rubber ◽  
Process Analysis ◽  
Modified Starch ◽  
Curing Period ◽  
Rubber Composite ◽  
Carbon Bisulfide ◽  
Vulcanization Kinetics ◽  
Starch Paste ◽  
Kinetics Of

The starch xanthate/natural rubber (SX/NR) composite was prepared by directly mixing and co-coagulating NR latex and the modified starch paste with carbon bisulfide. The vulcanization kinetics of NR and SX/NR composite were investigated by using a rubber process analysis (RPA). The mechanism of SX/NR composite vulcanization was similar to that of pure NR. The values t0and tdisof XS/NR composite were shorter than that of NR, and the activation energy E1for the induction period was smaller. The activation energies E2and E3for the curing period were smaller than that of NR.

Vulcanization of Elastomers. 40. Vulcanization of Natural Rubber and Synthetic Rubber with Sulfur in Presence of Sulfenamides. III

1965 ◽  
Vol 38 (1) ◽  
pp. 189-203 ◽  
Author(s):  
W. Scheele ◽  
J. Helberg
Keyword(s):  
Activation Energy ◽  
Reaction Mechanism ◽  
Natural Rubber ◽  
Rate Constants ◽  
Sulfur Concentration ◽  
Kcal Mole ◽  
Synthetic Rubber ◽  
Chemical Constitution ◽  
Induction Times ◽  
Kinetics Of

Abstract Vulcanization of natural rubber with sulfur was studied in presence of six sulfenamides, to determine the effect of the chemical constitution of the sulfenamide on sulfur decrease and on crosslinking. The results can be condensed as follows: (1) The kinetics of sulfur disappearance is in every respect qualitatively independent of the chemical constitution of the sulfenamide. (2) For the sulfenamides investigated, the smallest and largest rate constants for sulfur decrease differed only by a factor of two. (3) Greater differences are encountered in the induction times for sulfur decrease and for crosslinking. The latter are notably longer than those for sulfur disappearance. (4) The same activation energy, 23 kcal/mole, is derived from the temperature dependence of the induction times for all the sulfenamides. (5) The dissociation of sulfenamides in solution and their reaction with mercaptobenzothiazole were investigated further. The results provide the basis for a proposed reaction mechanism, which is presented in detail and can account for a number of the features typical of sulfenamide-accelerated vulcanization. (6) The drop in sulfur concentration goes at practically the same rate, if one introduces, instead of N, N-dicyclohexyl-2-benzothiazolesulfenamide, the corresponding ammonium mercaptide in equimolar concentration.

Investigations in the Field of Rubber Vulcanization. VII. Influence of Organic Accelerators on the Kinetics of Vulcanization and the Properties of Natural-Rubber Vulcanizates

1950 ◽  
Vol 23 (3) ◽  
pp. 563-575
Author(s):  
B. Dogadkin ◽  
B. Karmin ◽  
A. Dobromyslova ◽  
L. Sapozhkova
Keyword(s):  
Activation Energy ◽  
Natural Rubber ◽  
Oxidative Destruction ◽  
Tetramethylthiuram Disulfide ◽  
Vulcanization Kinetics ◽  
Strength Curve ◽  
Increasing Temperature ◽  
Low Sulfur ◽  
Natural Rubber Vulcanizates ◽  
Kinetics Of

Abstract 1. Vulcanization accelerators change all parameters of the kinetic strength curve during the vulcanization of natural-rubber mixtures with low sulfur contents. 2. Calculation of the kinetic constants of the fundamental vulcanization equation proposed by Dogadkin, Karmin, and Gol'berg shows that vulcanization accelerators affect both the kinetics of the interaction of rubber with sulfur and the kinetics of the interaction of rubber with oxygen. 3. Direct experiments on the oxidation of rubber have shown that tetramethylthiuram disulfide and diphenylguanidine retard the process of addition of oxygen to rubber, while mercaptobenzothiazole accelerates this process. 4. Data on the rate of plasticization and change in viscosity of rubber solutions during oxidation indicate that tetramethylthiuram disulfide and diphenylguanidine promote the disintegration of molecular chains of rubber during the oxidative destruction of the latter. 5. The activation energy of the process of oxidation of rubber in the presence of mercaptobenzothiazole corresponds to the activation energy calculated from the fundamental vulcanization reaction for the process of oxidative destruction. This provides additional proof of the participation of oxygen in the vulcanization process. 6. It has been established with the aid of the methyl iodide reaction that accelerators increase the bridge-sulfur content of the vulcanizate, which is present in the form of monosulfides, with one sulfur atom connected to an allyl type radical. 7. With increasing temperature, the tensile strength at the vulcanization optimum increases in mixtures containing tetramethylthiuram disulfide, decreases in mixtures containing mercaptobenzothiazole, and remains unchanged in mixtures containing diphenylguanidine. The limiting strength decreases in all cases with increasing temperature. This phenomenon is explained on the basis of the proposed concepts of the character of vulcanization kinetics and of the nature of the vulcanization optimum.

Vulcanization of Elastomers. 12. Perbunan with Thiuram Monosulfide and Sulfur. I

1959 ◽  
Vol 32 (1) ◽  
pp. 128-138 ◽  
Author(s):  
Walter Scheele ◽  
Horst-Eckart Toussaint
Keyword(s):  
Activation Energy ◽  
Natural Rubber ◽  
Temperature Dependence ◽  
Induction Period ◽  
Rate Constants ◽  
The Other ◽  
Tetramethylthiuram Disulfide ◽  
First Order ◽  
The One ◽  
Limiting Value

Abstract The vulcanization of Perbunan 2818 by tetramethylthiuram monsulfide plus sulfur (1 mole monosulfide per gram-atom S) was thoroughly studied. The following results were shown: The limiting value for dithiocarbamate formation is 66 mole per cent of the initial thiuram monosulfide, indicating a two-thirds transformation. The limiting value is practically independent of temperature. The formation of dithiocarbamate can be described as a reaction of the first order. The formation of dithiocarbamate is characterized by an induction period which grows longer with lowering of the temperature, and at 100° C it amounts to about 100 minutes. The rate constants for dithiocarbamate formation were calculated, and it was shown that they were practically the same as those for the vulcanization of Perbunan with tetramethylthiuram disulfide. The activation energies as derived from the temperature dependence of the rate constants for dithiocarbamate formation in the vulcanization of Perbunan by thiuram monosulfide plus sulfur on the one hand and with thiuram disulfide on the other, are only very slightly different and are practically the same as the activation energy for dithiocarbamate formation during the vulcanization of natural rubber with thiuram monosulfide plus sulfur. The results were thoroughly discussed in light of the present conceptions of the course of thiuram vulcanizations.

Vulcanization Kinetics of Natural Rubber Coagulated by Microorganisms with Use of a Vulcameter

2010 ◽  
Vol 160-162 ◽  
pp. 1181-1186 ◽  
Author(s):  
Zhi Feng Wang ◽  
Si Dong Li ◽  
Xiao Dong She
Keyword(s):  
Activation Energy ◽  
Natural Rubber ◽  
Rate Constants ◽  
Order Reaction ◽  
First Order Reaction ◽  
First Order ◽  
Second Stage ◽  
End Stage ◽  
Two Stages ◽  
Kinetics Of

Kinetics of vulcanization of natural rubber coagulated by microorganisms (NR-m) was studied with the use of a vulcameter. In the induction period of vulcanization, the time t0 of NR-m is shorter than that of natural rubber coagulated by acid (NR-a), and the rate constant k1/a of NR-m are greater than that of NR-a. Both the curing periods of NR-m and NR-a consist of two stages. The first stage follows first-order reaction. The rate constants k2 of NR-m in the first stage are greater than that of NR-a at the same temperature, and so are the activation energy E2. The second stage (end stage of the curing period) does not follow first-order reaction, and the calculated reaction order n of NR-m is in the range of 0.82-0.85, and that of NR-a is in the range of 0.64-0.72. The rate constants k3 of the second stage for NR -m are greater than that of NR-a at the same temperature, and so is the activation energy E3.

Vulcanization kinetics of natural rubber-organoclay nanocomposites

2003 ◽  
Vol 89 (1) ◽  
pp. 1-15 ◽  
Author(s):  
M. A. López-Manchado ◽  
M. Arroyo ◽  
B. Herrero ◽  
J. Biagiotti
Keyword(s):  
Natural Rubber ◽  
Vulcanization Kinetics ◽  
Kinetics Of

scholarly journals The Kinetics of Peroxynitrite on Insulin Nitration Damage

2020 ◽  
Author(s):  
Congxiao Zhang ◽  
Fusheng Sun ◽  
Congjiang Zhang ◽  
Yunjing Luo
Keyword(s):  
Activation Energy ◽  
Biological Activity ◽  
Glucose Metabolism ◽  
Rate Constants ◽  
The Body ◽  
Stopped Flow ◽  
Tyrosine Nitration ◽  
Protein Nitration ◽  
Physiological Conditions ◽  
Kinetics Of

Abstract Background: Insulin is one of the most important versatile hormones that is central to regulating the energy and glucose metabolism in the body. There has been accumulating evidence supporting that diabetes was associated with peroxynitrite and protein nitration, and insulin nitration induced by peroxynitrite affected its biological activity. Methods: In this paper, the kinetics of insulin nitration by peroxynitrite in physiological conditions was studied by the stopped flow technique. Results: We determined the values of the reactive rate constants of peroxynitrite decomposition and peroxynitrite-induced tyrosine nitration in the presence of insulin. The activation energy of peroxynitrite decomposition and 3-nitrotyrosine yield in the presence of insulin is 48.8 kJ·mol−1 and 42.7 kJ·mol−1 respectively. Conclusions: It is inferred that the glutamate residue of insulin accelerated peroxynitrite decomposition and tyrosine nitration by reducing the activation energy of reactions. The results could be beneficial for exploring the molecular mechanism of diabetes and offering a new target for diabetes therapies.

Study on vulcanization kinetics of constant viscosity natural rubber by using a rheometer MDR2000

2013 ◽  
Vol 130 (1) ◽  
pp. 47-53 ◽  
Author(s):  
Zhang Bei-Long ◽  
Wang Yong-Zhou ◽  
Wang Ping-Yue ◽  
Huang Hong-Hai
Keyword(s):  
Natural Rubber ◽  
Vulcanization Kinetics ◽  
Constant Viscosity ◽  
Kinetics Of

Kinetics of Peroxide Vulcanization of Natural Rubber

2012 ◽  
Vol 28 (4) ◽  
pp. 201-220 ◽  
Author(s):  
Rejitha Rajan ◽  
Siby Varghese ◽  
K.E. George
Keyword(s):  
Mechanical Properties ◽  
Natural Rubber ◽  
Crosslinking Agent ◽  
Decomposition Reaction ◽  
Dominant Factor ◽  
Compression Set ◽  
Cure Time ◽  
Minimum Residual ◽  
Vulcanization Kinetics ◽  
Kinetics Of

This study was undertaken to optimize the vulcanization conditions and explore the effect of residual peroxide in the peroxide vulcanization of natural rubber. The study was followed through the kinetics of the vulcanization reaction at various temperatures viz. 150,155,160 and 165°C. Dicumyl peroxide (DCP) was used as the crosslinking agent. The Monsanto Rheometer was used to investigate the different crosslinking stages and vulcanization kinetics. The thermal decomposition of peroxide followed a first order free radical decomposition reaction. Half-lives at various temperatures were determined. The percentage of residual peroxide was calculated from the cure kinetic data. The effect of residual peroxide on mechanical properties was studied at various peroxide levels and also by extending the cure time (from t90 to t95 and then to t100). Mechanical properties such as tensile strength, elongation at break, modulus and compression set (70 and 100°C) were measured. Excess peroxide was found to cause a high compression set at elevated temperature and the cure time was selected to achieve minimum residual peroxide in the product. Results indicate that peroxide concentration is the dominant factor controlling the crosslink density and hence the properties of the vulcanizates.

Kinetics of Crosslinking and Network Changes in Natural Rubber Vulcanizates with a Dithiodimorpholine Based Accelerator System

1980 ◽  
Vol 53 (5) ◽  
pp. 1015-1022 ◽  
Author(s):  
A. K. Bhowmick ◽  
S. K. De
Keyword(s):  
Natural Rubber ◽  
Rate Constants ◽  
Crosslink Density ◽  
Curing Temperature ◽  
Side Reactions ◽  
Filler Surface ◽  
Natural Rubber Vulcanizates ◽  
Kinetics Of ◽  
Accelerator System

Abstract Kinetics of crosslinking and network changes in unfilled and filled natural rubber vulcanizates with a dithiodimorpholine based accelerator system have been studied at 150° and 180°C. Results show that addition of HAF black enhances the polysulfidic crosslinks as well as the total crosslinks. This has been explained with the help of Coran's model wherein HAK black increases the rate constants. It is likely that the filler surface prevents desulfuration and undesirable side reactions involving the crosslink precursors. Increase of curing temperature by 30°C lowers the total crosslink density and increases the sulfur inefficiency.

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