Complexation of the Vulcanization Accelerator Tetramethylthiuram Disulfide and Related Molecules with Zinc Compounds Including Zinc Oxide Clusters (Zn4O4)

2008 ◽  
Vol 14 (3) ◽  
pp. 919-932 ◽  
Author(s):  
Ralf Steudel ◽  
Yana Steudel ◽  
Ming Wah Wong
Keyword(s):  
Zinc Oxide ◽  
Tetramethylthiuram Disulfide ◽  
Zinc Compounds ◽  
Vulcanization Accelerator

The Interaction of Sulfur and Sulfur Compounds with Olefinic Substances. VII. Low-Temperature Sulfuration of Trialkylethylenes with Hydrogen Sulfide-Sulfur Dioxide and with a Sulfur-Zinc Dithiocarbamate System

1955 ◽  
Vol 28 (2) ◽  
pp. 470-479
Author(s):  
E. H. Farmer ◽  
J. F. Ford ◽  
J. A. Lyons
Keyword(s):  
Zinc Oxide ◽  
Hydrogen Sulfide ◽  
Sulfur Dioxide ◽  
Low Temperature ◽  
Room Temperature ◽  
Cross Linking ◽  
Sulfide Sulfur ◽  
Tetramethylthiuram Disulfide ◽  
Zinc Compounds ◽  
Low Concentrations

Abstract The sulfuration of trialkylethylenes with hydrogen sulfide-sulfur dioxide at 0° C (Peachey process) results in disubstitutive cross-linking of the olefins, yielding dialkenyl tetrasulfides. At higher temperatures, substitutive-additive cross-linking occurs, and alkyl alkenyl polysulfides are formed. Dialkenyl tetrasulfides are similarly formed by causing the olefin to react with sulfur at room temperature in the presence of zinc oxide and zinc dibutyldithiocarbamate, low concentrations of hydrogen sulfide acting as a catalyst for this reaction. At higher temperatures, the reaction is also exclusively disubstitutive, a feature connected with the function of zinc compounds in influencing the cross-linking reaction. The sulfuration of olefins with tetramethylthiuram disulfide at 140° C shows a similar influence of zinc compounds.

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.

Tetramethylthiuram Disulfide Vulcanization of Extracted Rubber. II. Structure of Radioactive Tetramethylthiuram Disulfide

1951 ◽  
Vol 24 (2) ◽  
pp. 262-265
Author(s):  
David Craig ◽  
W. L. Davidson ◽  
A. E. Juve ◽  
I. G. Geib
Keyword(s):  
Zinc Oxide ◽  
Pyrolysis Products ◽  
Tetramethylthiuram Disulfide ◽  
Theoretical Yield ◽  
Other Substances ◽  
Vulcanize Rubber

Abstract Tetra-substituted thiuram polysulfides are notable because of their action as “accelerators” in rubber vulcanization and also because of their ability to vulcanize rubber without added sulfur, especially in the presence of zinc oxide, which leads to the formation of zinc dimethyldithiocarbamate (ZnDMDC) and other substances. A study of the structure of tetramethylthiuram disulfide (TMTD) is reported in this paper. This has involved the introduction of radioactive sulfur. A corollary has been the similar study of ZnDMDC, which is an “accelerator” but not a vulcanizing agent. The synthesis of radioactive TMTD (i.e., TMTD*) was accomplished by heating 4.16 grams (0.02 mole) of tetramethylthiuram monosulfide (TMTM) and 1.28 grams (0.04 atom) of radiosulfur (S*8) to 120° in a stream of nitrogen for 30 minutes. By extraction with hot alcohol and benzene, a series of crystalline fractions was secured which totaled 3.38 grams, a yield of 70 per cent. This material melted at 150–156° C, with decomposition. The excess S*8 was recovered in a second experiment. Pyrolysis of the TMTD* prepared in the above manner was carried out at 160–230° C in a modified Claisen flask. There were produced S8*, tetramethylthiourea*, and CS2* in nearly theoretical yield. The radioactivities of the thiuram disulfide and of the pyrolysis products (the CS2* being converted to phenylhydrazinium phenyldithiocarbazate* or to 1-phenylthiosemicarbazide* for study), which are recorded in Table I, show that the tracer sulfur atoms distributed themselves uniformly throughout the various molecules.

The Crosslinks in TMTD-Zinc Oxide-Natural Rubber Vulcanizates

1960 ◽  
Vol 33 (2) ◽  
pp. 394-397 ◽  
Author(s):  
C. G. Moore
Keyword(s):  
Zinc Oxide ◽  
Natural Rubber ◽  
Appreciable Amount ◽  
Dicumyl Peroxide ◽  
Swelling Properties ◽  
Tetramethylthiuram Disulfide ◽  
Chemical Studies ◽  
The Subject ◽  
Natural Rubber Vulcanizates ◽  
Recent Experimental Work

Abstract The mechanism of vulcanization of natural rubber (NR) by means of tetramethylthiuram disulfide (TMTD) and zinc oxide has been the subject of much recent experimental work and speculation. While such studies have clarified the kinetics and stoichiometry of TMTD decomposition and zinc dimethyldithiocarbamate formation, they have not directly aided our knowledge of the nature of the crosslinks in the resultant vulcanizate. It was earlier suggested that the vulcanizate contained only C—C crosslinks, comparable with those formed by means of di-tert-alkyl (and aralkyl) peroxides, while more recently, disulfide crosslinks have been proposed. However, neither of these views has been confirmed by direct chemical studies of the vulcanizate. Evidence is now presented which shows that there can be no appreciable amount of C—C crosslinking by the TMTD-ZnO combination, and this is consistent with the view that sulfur crosslinks predominate. This conclusion is based on the respective swelling properties in n-decane of dicumyl peroxide vulcanizates (containing only C—C crosslinks) and TMTD-ZnO vulcanizates, which have been treated with methyl iodide in vacuo at 80° C. This reagent is known to cause the fission of C—S and S—S bonds in variously constituted organic mono- and polysulfides and should therefore cause the fission of sulfur crosslinks in a vulcanizate with consequent degradation of the network (cf. Ref. 8), whereas there is no evidence that di-allylic C—C crosslinks can be similarly degraded.

Mechanism of Formation of Zinc Dimethyldithiocarbamate (ZnDMDC) in Tetramethylthiuram Disulfide (TMTD) Vulcanization

1956 ◽  
Vol 29 (3) ◽  
pp. 944-945 ◽  
Author(s):  
David Craig
Keyword(s):  
Zinc Oxide ◽  
Mechanism Of Formation ◽  
Tetramethylthiuram Disulfide ◽  
Rate Law ◽  
First Order ◽  
Order Rate ◽  
Excess Zinc

Abstract Scheele and Bielstein recently have commented at length on the copolymerization (CP) theory of vulcanization which we proposed. They find the theory untenable with respect to TMTD vulcanization as well as with that using equivalent amounts of tetramethylthiuram monosulfide (TMTM) and sulfur. They feel that our presentation lacked in clarity and, therefore, that they did not understand it fully. Scheele and coworkers report that 66 per cent of the TMTD, or of the mixture of equivalent amounts of TMTM and sulfur, reacts to form ZnDMDC according to the first-order rate law during vulcanization in the presence of excess zinc oxide. This finding is a notable contribution. In particular, it suggests the possibility of sulfur-oxygen interchange as a feature of the overall reaction, which we may write:

Field-effect transistor performance of zinc oxide thin films derived from molecular based alkoxyalkyl zinc compounds

2011 ◽  
Vol 208 (7) ◽  
pp. 1708-1713 ◽  
Author(s):  
Rudolf C. Hoffmann ◽  
Stefan Dilfer ◽  
Alexander Issanin ◽  
Jörg J. Schneider
Keyword(s):  
Thin Films ◽  
Zinc Oxide ◽  
Field Effect ◽  
Field Effect Transistor ◽  
Oxide Thin Films ◽  
Zinc Compounds ◽  
Effect Transistor

Tetramethylthiuram Disulfide Vulcanization of Extracted Rubber. I. Introduction and Compounding

1951 ◽  
Vol 24 (2) ◽  
pp. 254-262 ◽  
Author(s):  
David Craig ◽  
A. E. Juve ◽  
W. L. Davidson
Keyword(s):  
Zinc Oxide ◽  
Palmitic Acid ◽  
Zinc Sulfide ◽  
Main Product ◽  
Tetramethylthiuram Disulfide ◽  
Effective Activator

Abstract (1) Large dosages of TMTM inhibit TMTD vulcanization or vulcanization with sulfur. (2) The desirability of up to about 1.5 phr zinc oxide for TMTD vulcanization was confirmed. If an unusually large amount of TMTD (10 phr) is used, a well vulcanized stock may be obtained without zinc activation. (3) Palmitic acid displays only a mild activating effect on TMTD vulcanization. (4) Zinc dimethyldithiocarbamate, a main product of TMTD vulcanization, is not an activator for a TMTD-zinc oxide recipe. (5) Dimethylammonium dimethyldithiocarbamate does not activate TMTD-zinc oxide formulations. (6) Zinc sulfide is an effective activator for TMTD vulcanization.

Acceleration by Thiourea and Related Compounds of the Tetramethylthiuram Disulfide Vulcanization of Natural Rubber

1961 ◽  
Vol 34 (3) ◽  
pp. 795-797 ◽  
Author(s):  
C. G. Moore ◽  
B. Saville ◽  
A. A. Watson
Keyword(s):  
Zinc Oxide ◽  
Natural Rubber ◽  
Tetramethylthiuram Disulfide ◽  
Reasonable Explanation ◽  
Vulcanization Process ◽  
Related Compounds ◽  
Curing Systems

Abstract It has recently been discovered that thiourea and certain of its N-derivatives and chemically related compounds, accelerate the vulcanization of natural rubber (NR) by tetramethylthiuram disulfide (TMTD)-zinc oxide combinations to such an extent that excellent vulcanizates can be produced at 100° C or lower. A reasonable explanation of this acceleration is now offered, based on a theory of vulcanization by TMTI) and related “sulfurless” curing systems currently being developed here. This theory recognizes the importance of polysulfidic intermediates (I, m>2), formed during the vulcanization process, which subsequently react with the polyisoprene to yield further intermediates (II) which finally react to yield sulfurated crosslinks. The process is broadly schematized as follows:

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