Reaction of a Thiuram and Sulfur

1955 ◽  
Vol 28 (3) ◽  
pp. 804-807
Author(s):  
G. A. Blokh ◽  
L. P. Sazonova
Keyword(s):  
Chemical Reactions ◽  
Chemical Structure ◽  
Elemental Sulfur ◽  
Practical Interest ◽  
Previous Article ◽  
Tetramethylthiuram Disulfide ◽  
Mercapto Group ◽  
Cable Industry ◽  
Isotopic Method ◽  
Vulcanize Rubber

Abstract In a previous article the occurrence of an intensive interchange between atoms of elemental sulfur when present as vulcanizing agent and the sulfur atoms of the mercapto group of mercaptobenzothiazole as accelerator was shown by the isotopic method, i.e., by the application of tagged atoms of radioactive sulfur. Thus, the existence of a reaction between the accelerator and the vulcanizing agent during the vulcanization of rubber was established. The application of isotopes as tagged atoms is an effective new method of investigating the chemical structure of substances, their reactivities, and the mechanism of chemical reactions in which they take part. This method is being successfully developed in our country, particularly by the work of Brodskii˘ and his pupils. The present study is devoted to the problem of the reaction of tetramethylthiuram disulfide (hereafter called thiuram) and elemental sulfur. Studies in this field are of great scientific and practical interest, since the mechanism of the accelerating action of thiuram is not yet clear. We assume that the chemistry of the reaction is as follows. Thiuram is decomposed during vulcanization, with the formation of a dithiocarbamate and free active sulfur. Because of this, the thiuram can vulcanize rubber without the addition of elemental sulfur to the mixture. Such vulcanizates are particularly widely used in the cable industry.

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.

Infrared Study of Some Structural Changes in Natural Rubber during Vulcanization

1958 ◽  
Vol 31 (4) ◽  
pp. 719-736 ◽  
Author(s):  
Frederic J. Linnig ◽  
James E. Stewart
Keyword(s):  
Double Bond ◽  
Gamma Rays ◽  
Structural Changes ◽  
Elemental Sulfur ◽  
Carboxyl Groups ◽  
Double Bonds ◽  
Infrared Study ◽  
Tetramethylthiuram Disulfide ◽  
Vulcanized Rubber ◽  
Double Bond Shift

Abstract A knowledge of the structure of vulcanized rubber is essential to the interpretation of vulcanization and oxidation studies and the physical properties of the material. In the present work an infrared study has been made of structures resulting from a number of different methods of vulcanization. Sulfur vulcanizates show the presence of a shifted double bond, originally observed by Sheppard and Sutherland. The presence of conjugated double bonds is also indicated. Accelerators such as tetramethylthiuram disulfide and zinc dibutyl dithiocarbamate increase the rate of the double-bond shift and reduce the amount of conjugated double bonds. Neither the double-bond shift nor conjugation is observed as a result of vulcanization with tetramethylthiuram disulfide alone, hydrogen sulfide and sulfur dioxide (Peachey process), a peroxide, or gamma rays. These result in a possible decrease in carbonyl structures, and in the case of the last three, possible increased absorption due to OH and ionized carboxyl groups. Apparently, the double-bond shift and conjugation are primarily phenomena related to the use of elemental sulfur. The other vulcanization systems studied evidently involve different mechanisms. An implication of the present work is that there may be a relationship between the reported ease of oxidation of sulfur vulcanizates, accelerated vulcanizates, and sulfurless vulcanizates (tetramethylthiuram disulfide alone), which decreases in the order named, and the probable amount of conjugation in the compound, which decreases in the same order.

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.

scholarly journals Anionic Copolymerization of Styrene Sulfide with Elemental Sulfur (S8)

Materials ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2597
Author(s):  
Jakub Wręczycki ◽  
Dariusz M. Bieliński ◽  
Marcin Kozanecki ◽  
Paulina Maczugowska ◽  
Grzegorz Mlostoń
Keyword(s):  
Thermal Stability ◽  
Raman Spectroscopy ◽  
Ring Opening ◽  
Chemical Structure ◽  
Elemental Sulfur ◽  
Ring Opening Polymerization ◽  
Spectroscopic Methods ◽  
Initial Ratio ◽  
Anionic Copolymerization ◽  
Thermal Stability Of

The superior ability of thiiranes (episulfides) to undergo ring-opening polymerization (ROP) in the presence of anionic initiators allows the preparation of chemically stable polysulfide homopolymers. Incorporation of elemental sulfur (S8) by copolymerization below the floor temperature of S8 permits the placement of a large quantity of sulfur atoms in the polysulfide mainchain. The utility of styrene sulfide (2-phenylthiirane; StS) for copolymerization with elemental sulfur is reported here. A few polysulfides differing depending on the initial ratio of S8 to StS and copolymerization time were synthesized. Various spectroscopic methods (1H NMR, 13C NMR, Raman spectroscopy and FTIR spectroscopy) were applied to characterize the chemical structure of the copolymers. Additionally, the phase structure and thermal stability of the synthesized polysulfides were investigated using DSC and TGA, respectively. The successful anionic copolymerization of styrene sulfide and elemental sulfur has been demonstrated.

A Scheme for Accelerator Classification

1928 ◽  
Vol 1 (3) ◽  
pp. 410-421 ◽  
Author(s):  
R. P. Dinsmore ◽  
W. W. Vogt
Keyword(s):  
Chemical Structure ◽  
Practical Interest ◽  
Chemical Behavior ◽  
The Mind

Abstract MUCH has been written about the constitution and chemical behavior of vulcanization accelerators. Theories have been advanced regarding the mechanism of vulcanization effected with their aid. Yet even the authors of such papers—presumably best qualified to interpret their contents—would hesitate to predict, from chemical structure, many of those features which are of practical interest to the rubber manufacturer. Nevertheless, an increasing number and variety of organic accelerators are being offered on the market, and it is not strange that the mind of the average rubber man is confused by the excess at his command and the conflicting claims of the distributors. In these circumstances it is natural to hesitate to undertake the somewhat formidable task of sorting and classifying. Fortunately, however, it is not necessary to do all the work of classification on a factory scale. Certain laboratory helps are available and can be used to reduce considerably the arduousness of the task. It is believed that an outline of such methods, a discussion of their significance, and a table of results, may be helpful to many in the industry, and it is for this purpose that this paper has been written.

The Reliability of Pesticide Determinations Using near Infrared Spectroscopy and the Dry-Extract System for Infrared (DESIR) Technique

2007 ◽  
Vol 15 (4) ◽  
pp. 227-236 ◽  
Author(s):  
Sirinnapa Saranwong ◽  
Sumio Kawano ◽  
Keyword(s):  
Dipole Moment ◽  
Chemical Structure ◽  
Near Infrared ◽  
Collaborative Study ◽  
Control Level ◽  
Previous Article ◽  
Dry Extract ◽  
Sample Extract ◽  
Sample Presentation ◽  
Strong Dipole

In a previous article, a pesticide determination system using near infrared (NIR) spectroscopy and the dry-extract system for infrared (DESIR) technique had been developed. In order to evaluate system reliability, a number of tests had been conducted. To reduce time and labour needed for pesticide assays by gas chromatography, artificial solutions of each pesticide in acetone were used in place of sample extract that was used in the previous article. Effects of several factors, such as chemical structure, interference of another reagent in the solution and sample presentation, on the system accuracy were evaluated. A tentative collaborative study was conducted to evaluate the possibility of large scale utilisation. To test the influence of chemical structure, three pesticides— acephate, dichlofluanid and tetrachloro-isophthalonitrile (TPN)—having different numbers of functional groups with strong dipole moment were used. From the range of 0 ppm to 50 ppm active ingredient in acetone, the SEPs obtained were 2.1, 5.3 and 9.3 ppm for acephate, dichlofluanid and TPN, respectively. These results corresponded to the number of strong dipole moment groups in the chemical structure which were four for acephate, two for dichlofluanid and none for TPN. In the case where two kinds of pesticide were presented in the system, the SEP became larger compared to the single pesticide results. The degree of interference differed depending on the relative absorptivity between the target pesticide and the interference. Using the system developed and acephate solution, a tentative collaborative study was conducted using three laboratories and four technicians. The almost similar SEPs of 2.8, 2.8, 3.0 and 2.5 ppm were obtained by the four technicians, indicating that even if the NIR instruments used and the degree of professional skill differed between technicians, satisfactory results could be obtained after a few hours of training and a proper bias correction. Finally, to simplify the system, three kinds of sample presentation were used to develop a calibration equation for acephate. The SEPs obtained differed only minutely. It could be concluded that when using NIR analysis the operator may choose between the highly precise system which requires more time and labour because of the sample preparation involved or a slightly less precise system with simple sample presentation. Based on the Japanese pesticide control level, the developed system could be used for the monitoring of some pesticides in fruits and vegetables.

Radiotracer Studies of Carbon Black Surface Interactions with Organic Systems. II. Use of Sulfur-35 in Initial Studies on the Reactivity of “Bound” Surface Sulfur

1970 ◽  
Vol 43 (2) ◽  
pp. 449-463 ◽  
Author(s):  
J. E. Lewis ◽  
M. L. Deviney ◽  
C. F. McNabb
Keyword(s):  
Carbon Black ◽  
Pilot Plant ◽  
Elemental Sulfur ◽  
Chemical Reactivity ◽  
Phosphorus Compounds ◽  
Tetramethylthiuram Disulfide ◽  
Organic Systems ◽  
Physical Testing ◽  
Carbon Black Surface ◽  
Black Surface

Abstract A broad investigation has been undertaken, using primarily radiochemical techniques, of the reactivity of the insoluble or “bound” sulfur on the surface of carbon blacks. The carbon black samples used in this study were prepared in small pilot plant reactors from sulfur-free commercial feedstocks to which had been added, in separate experiments, sulfur-35 tagged elemental sulfur, dibenzothiophene-S-35 and dibenzyl disulfide-S-35. After careful extraction-purification of the blacks, “chemical probe” studies were undertaken to gain knowledge of the nature of the surface sulfur complexes or functional groups, using reagents such as LiAlH4, trivalent phosphorus compounds, tetramethylthiuram disulfide, and hydrogen. These experiments demonstrated that bound surface sulfur possesses a considerable amount of chemical reactivity. Experiments were next designed to determine whether or not bound surface sulfur becomes involved in vulcanization reactions by, for example, exchange with added curing sulfur or accelerator. In radiotracer studies with SBR, natural rubber, and cis-polybutadiene vulcanizates, the results demonstrated that bound surface sulfur enters into the rubber phase during vulcanization. Finally, results from preliminary rubber physical testing and practical vulcanization studies involving pilot plant blacks (2% wt. sulfur) indicate that surface sulfur has little effect upon the vulcanization or final physical properties of SBR and NR.

Metabolism of Fungicides by Plants and Micro-Organisms

1964 ◽  
Vol 4 (3) ◽  
pp. 119-125 ◽  
Author(s):  
A. Kaars Sijpesteijn ◽  
J. Kaslander
Keyword(s):  
Chemical Reactions ◽  
Practical Interest ◽  
Metabolic Fate ◽  
Present Contribution ◽  
Systemic Activity ◽  
Micro Organisms

The metabolic fate of pesticides and herbicides in plants and animals is a topic of practical interest both to research workers who are striving to reduce the risk of toxic residues and to those looking for chemicals that possess systemic activity. Typical of this kind of investigation is the present contribution from Utrecht that illustrates how foreign substances may become embroiled in the intimate chemical reactions of organisms.

scholarly journals Strong Reachability of Reactions with Reversible Steps

2018 ◽  
Vol 46 (2) ◽  
pp. 19-25
Author(s):  
Eszter Virágh ◽  
Bálint Kiss
Keyword(s):  
Ambient Temperature ◽  
Chemical Reactions ◽  
Chemical Industry ◽  
Input Signal ◽  
Practical Interest ◽  
Efficient Production ◽  
Dynamical Models ◽  
Great Practical Interest

Abstract The controllability of reactions is an important issue in the chemical industry. The control of reactions is of great practical interest in order to ensure the energy- and time-efficient production of compounds. This paper studies the dynamical models of some chemical reactions in order to verify their controllability with regard to a candidate input signal, namely the change in the ambient temperature of a reaction.

scholarly journals Toughening Hydrogels Through Force-triggered Chemical Reactions that Lengthen Polymer Strands

2021 ◽  
Author(s):  
Zi Wang ◽  
Xu Jun Zheng ◽  
Tetsu Ouchi ◽  
Tatiana Kouznetsova ◽  
Haley Beech ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Chemical Reactions ◽  
Chemical Structure ◽  
Polymer Networks ◽  
Breaking Point ◽  
Network Architectures ◽  
Material Synthesis ◽  
Double Network ◽  
Cross Links ◽  
Coupled Reactions

<p>The utility and lifetime of materials made from polymer networks, including hydrogels, depend on their capacity to stretch and resist tearing. In gels and elastomers, those mechanical properties are often limited by the covalent chemical structure of the polymer strands between cross-links, which is typically fixed during the material synthesis. Here, we report polymer networks in which the constituent strands lengthen through force-coupled reactions that are triggered as the strands reach their nominal breaking point. Reactive strand extensions of up to 40% lead to hydrogels that stretch 40-50% further than, and exhibit tear energies twice that of, networks made from analogous control strands. The enhancements are synergistic with those provided by double network architectures, and complement other existing toughening strategies. </p>

Sign in / Sign up

Export Citation Format

Share Document