Complexes of tetramethylthiuram disulfide with zinc dialkyldithiocarbamates and their role in the sulfur vulcanization of natural rubber

1979 ◽  
Vol 23 (7) ◽  
pp. 2065-2071 ◽  
Author(s):  
V. Ducháček ◽  
R. Frenkel
Keyword(s):  
Natural Rubber ◽  
Tetramethylthiuram Disulfide ◽  
Sulfur Vulcanization

Effect of Sulfur and Dicumyl Peroxide on Vulcanization of Natural Rubber with Tetramethylthiuram Disulfide and Zinc Oxide

1970 ◽  
Vol 43 (6) ◽  
pp. 1294-1310 ◽  
Author(s):  
S. P. Manik ◽  
S. Banerjee
Keyword(s):  
Zinc Oxide ◽  
Stearic Acid ◽  
Natural Rubber ◽  
Reaction Mechanisms ◽  
Elemental Sulfur ◽  
Initial Rate ◽  
Dicumyl Peroxide ◽  
Tetramethylthiuram Disulfide ◽  
Sulfur Vulcanization ◽  
Salient Features

Abstract The salient features of both non-elemental sulfur vulcanization by TMTD and elemental sulfur vulcanization promoted by TMTD both in presence and absence of ZnO and stearic acid have been studied. TMTD increases the rate of DCP decomposition and lowers the crosslinking maxima due to DCP depending on its concentration. However, with higher amounts of TMTD the initial rate of crosslinking is increased with the increased amount of TMTD, while crosslinking maxima are still lowered due to reversion. ZnO or ZnO-stearic acid, however, seems to alter the entire course of the reaction. Both the crosslink formation and TMTD decomposition are much higher in presence of ZnO or ZnO-stearic acid, but stearic acid seems to have no effect. The reaction mechanisms for TMTD accelerated sulfuration in absence and presence of ZnO have also been studied.

EFFECT OF BENZOTHIAZOLOYLTHIAZOLES AS SECONDARY ACCELERATORS IN THE SULFUR VULCANIZATION OF NATURAL RUBBER

2011 ◽  
Vol 84 (1) ◽  
pp. 88-100 ◽  
Author(s):  
R. Reshmy ◽  
R. Nirmal ◽  
S. Prasanthkumar ◽  
K. Kurien Thomas ◽  
Molice Thomas ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Natural Rubber ◽  
Chemical Method ◽  
Binary Systems ◽  
Minimal Amount ◽  
Tetramethylthiuram Disulfide ◽  
Solvent Free Conditions ◽  
Sulfur Vulcanization ◽  
Cure Time

Abstract The vulcanization of natural rubber and a blend of natural rubber and reclaimed rubber by using binary accelerator systems containing a novel series of benzothiazoloylthiazole as secondary accelerator (SA) has been studied. These secondary accelerators were synthesized by a green chemical method under solvent-free conditions, by the irradiation of microwaves (180 W). The synergistic effect of the SA with N-Cyclohexyl-2-benzothiazolsulfenamide as primary accelerator was studied at 150 °C. These binary systems were effective in reducing the cure time and improving the rheometric and mechanical properties. These SAs were found to be effective in reducing the cure time with a minimal amount of 0.5 phr, but commercially available SAs such as thioureas and tetramethylthiuram disulfide were reported to show reduction in cure time only by increasing the amount of SA. Mechanical properties such as hardness, abrasion loss, tensile strength, percentage strain at break, and modulus at different elongations 100, 200, and 300% were evaluated and found to be immensely improved. The improved mechanical properties were also shown to be at par with crosslink densities (1/2Mc) of different mixes.

Structural Characterization of Vulcan-Izates. XII. Efficient Vulcanization Using a Sulfenamide-Thiuram Disulfide Accelerator System

1972 ◽  
Vol 45 (5) ◽  
pp. 1366-1371 ◽  
Author(s):  
D. S. Campbell
Keyword(s):  
Natural Rubber ◽  
Structural Characterization ◽  
High Ratio ◽  
Mixed System ◽  
Tetramethylthiuram Disulfide ◽  
Sulfur Vulcanization ◽  
Cure Time ◽  
Accelerator System ◽  
Cyclic Sulfide

Abstract Vulcanizates obtained from the sulfur vulcanization of natural rubber using a combination of the accelerators N-cyclohexyl-2-benzothiazole sulfenamide (CBS) and tetramethylthiuram disulfide (TMTD) have been analyzed in terms of the numbers of poly-, di-, and monosulfide crosslinks, network-bound accelerator residues, and cyclic sulfide chain modifications as a function of cure time. The vulcanization system produced mainly monosulfide crosslinks at optimum cure, although there were differences in detail between this mixed system and a previously reported efficient sulfur vulcanization (EV) system using a high ratio of CBS to sulfur.

EFFECT OF ZINC DITHIOCARBAMATES AND THIAZOLE-BASED ACCELERATORS ON THE VULCANIZATION OF NATURAL RUBBER

2012 ◽  
Vol 85 (1) ◽  
pp. 120-131 ◽  
Author(s):  
Md. Najib Alam ◽  
Swapan Kumar Mandal ◽  
Subhas Chandra Debnath
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
Reaction Mechanism ◽  
Natural Rubber ◽  
High Performance ◽  
Binary Systems ◽  
Synergistic Activity ◽  
Tetramethylthiuram Disulfide

Abstract Several zinc dithiocarbamates (ZDCs) as accelerator derived from safe amine has been exclusively studied in the presence of thiazole-based accelerators to introduce safe dithiocarbamate in the vulcanization of natural rubber. Comparison has been made between conventional unsafe zinc dimethyldithiocarbamate (ZDMC) with safe novel ZDC combined with thizole-based accelerators in the light of mechanical properties. The study reveals that thiuram disulfide and 2-mercaptobenzothiazole (MBT) are always formed from the reaction either between ZDC and dibenzothiazyledisulfide (MBTS) or between ZDC and N-cyclohexyl-2-benzothiazole sulfenamide (CBS). It has been conclusively proved that MBT generated from MBTS or CBS reacts with ZDC and produces tetramethylthiuram disulfide. The observed synergistic activity has been discussed based on the cure and physical data and explained through the results based on high-performance liquid chromatography and a reaction mechanism. Synergistic activity is observed in all binary systems studied. The highest tensile strength is observed in the zinc (N-benzyl piperazino) dithiocarbamate-accelerated system at 3:6 mM ratios. In respect of tensile strength and modulus value, unsafe ZDMC can be successfully replaced by safe ZDCs in combination with thiazole group containing accelerator.

Sulfur Vulcanization of Simple Model Olefins, Part V: Double Bond Isomerization during Accelerated Sulfur Vulcanization as Studied by Model Olefins

1997 ◽  
Vol 70 (1) ◽  
pp. 106-119 ◽  
Author(s):  
P. Versloot ◽  
J. G. Haasnoot ◽  
P. J. Nieuwenhuizen ◽  
J. Reedijk ◽  
M. van Duin ◽  
...  
Keyword(s):  
Double Bond ◽  
Isomerization Reaction ◽  
Radical Mechanism ◽  
Formation Mechanisms ◽  
Molecular Models ◽  
Tetramethylthiuram Disulfide ◽  
Alkyl Substitution ◽  
Sulfur Vulcanization ◽  
The One ◽  
Vulcanization Process

Abstract The sulfur vulcanization of unsaturated rubber has been studied with the use of various olefins as simple, low-molecular models. By treatment of these olefins with a mixture of zinc oxide, sulfur, and tetramethylthiuram disulfide (TMTD) at 140 °C, a mixture of dialkenyl sulfides is obtained mimicking crosslinked rubber. Isomerization of the double bond may take place during this reaction, depending on the olefin used. The position of the double bond is on the one hand determined by crosslink formation mechanisms, and on the other hand by isomerization, which takes place at higher temperatures. The position of the equilibrium between isomeric alkenyl sulfides is determined by the increased stability of the sulfide which in itself results from an increased degree of alkyl substitution at the unsaturation. Due to the isomerization reaction, at higher temperatures no mechanism for crosslink formation can be discerned. At room temperature, however, a radical mechanism appears to be predominant during the vulcanization process.

Role of geopolymer as a cure activator in sulfur vulcanization of epoxidized natural rubber

2019 ◽  
Vol 137 (17) ◽  
pp. 48624
Author(s):  
Hassarutai Yangthong ◽  
Skulrat Pichaiyut ◽  
Suwaluk Wisunthorn ◽  
Claudia Kummerlöwe ◽  
Norbert Vennemann ◽  
...  
Keyword(s):  
Natural Rubber ◽  
Epoxidized Natural Rubber ◽  
Sulfur Vulcanization ◽  
Cure Activator

The Formation of Crosslink Precursors in the Sulfur Vulcanization of Natural Rubber

1984 ◽  
Vol 57 (1) ◽  
pp. 97-103 ◽  
Author(s):  
N. J. Morrison
Keyword(s):  
Natural Rubber ◽  
Zinc Complexes ◽  
Accelerator Complex ◽  
Sulfur Vulcanization ◽  
Rapid Formation

Abstract With the accelerator MDB and with MBTS-sulfur, the addition of a relatively small amount of the zinc-accelerator complex (1) caused rapid formation of model crosslinks in 2-methyl-2-pentene under conditions in which neither model crosslink precursors nor model crosslinks were formed appreciably in its absence. In the accelerated sulfur vulcanization of natural rubber, zinc complexes promote both the formation and subsequent reactions of crosslink precursors. At 140°C, the reaction of MBTS-sulfur with 2-methyl-2-pentene gives a disulfidic model crosslink precursor derived by substitution entirely at the methylene site. At 150°C, or in the presence of the zinc-accelerator complex (1) at 130–140°C, precursors are derived by substitution at methylene and methyl sites.

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