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.

Tetramethylthiuram Disulfide Vulcanization of Extracted Rubber. V. Low Molecular Products and the Mechanism of Zinc Oxide Activation

1951 ◽  
Vol 24 (2) ◽  
pp. 275-284 ◽  
Author(s):  
David Craig ◽  
W. L. Davidson ◽  
A. E. Juve
Keyword(s):  
Palmitic Acid ◽  
Good Yield ◽  
Main Product ◽  
Complete Removal ◽  
Tetramethylthiuram Disulfide ◽  
Short Path Distillation ◽  
Sulfur Vulcanization ◽  
Identical Part ◽  
Acidic Nature ◽  
Vulcanization Process

Abstract The essential features of TMTD vulcanization, as revealed by compounding tudies, were discussed in Part I of this series. Thus, TMTM, a product of TMTD vulcanization, and an active accelerator of sulfur vulcanization, was found to be an inhibitor, and ZnDMDC, a main product of TMTD vulcanization, in the presence of ZnO was found to be devoid of activating properties. As a replacement of ZnO, which is a potent activator, ZnDMDC displayed only mild activating effects. Zinc palmitate was even more potent than ZnO. Zinc sulfide was somewhat less active than ZnO. Palmitic acid and DMADC had little or no effect on the cure. The second paper reported that TMTD could be prepared in good yield by the reaction of TMTM with sulfur and also, as a result of radiosulfur techniques, that the four sulfur atoms in the TMTD molecule are chemically identical. Part II also reported that ZnO reacted with TMTD to form sulfur and ZnDMDC in good yield. Other reactions of TMTD were discussed. Part III, in presenting a short-path distillation technique for studying vulcanizates, reported that the nearly complete removal of zinc from the TMTD vulcanizate is not accompanied by devulcanization. Part IV reported on the behavior of rubber as an acid. This behavior results in the liberation of palmitic acid from zinc palmitate. From the comparison of the reaction of TMTD with acids and the reaction of rubber with TMTD, it was inferred that rubber is an OH-containing acid. Acids in the work reported were found to react rather slowly with TMTD to form dimethylamides and sulfur in good yield. The acidic nature of rubber did not seem to be great enough to contribute in any fundamental way to the vulcanization process. The present paper describes further studies of the TMTD vulcanization problem.

Tetramethylthiuram Disulfide Vulcanization of Extracted Rubber. IV. Behavior of Rubber as an Acid

1951 ◽  
Vol 24 (2) ◽  
pp. 269-275
Author(s):  
David Craig ◽  
A. E. Juve ◽  
W. L. Davidson
Keyword(s):  
Zinc Oxide ◽  
Organic Acids ◽  
Palmitic Acid ◽  
Present Series ◽  
Tetramethylthiuram Disulfide ◽  
Metallic Oxides ◽  
Retarding Effect ◽  
Acids And Bases

Abstract The retarding effect of organic acids on vulcanization as well as the activating effect of certain acids on certain accelerators is well recognized. The activating and accelerating effects of bases and metallic oxides is also well recognized. In this connection, the mild activating effect of palmitic acid on vulcanization with TMTD in the presence of zinc oxide was described in the first paper of the present series. With the behavior of acids and bases during vulcanization as a background, the study of rubber itself as an acid has been undertaken. This paper sets forth a description of two reactions investigated during the study. These are the reaction of rubber with zinc palmitate and of TMTD with acids.

Low-Temperature Thermal Expansion of Zinc Oxide. Vibrations in Zinc Oxide and Sphalerite Zinc Sulfide

1971 ◽  
Vol 4 (4) ◽  
pp. 1314-1323 ◽  
Author(s):  
B. Yates ◽  
R. F. Cooper ◽  
M. M. Kreitman
Keyword(s):  
Zinc Oxide ◽  
Thermal Expansion ◽  
Low Temperature ◽  
Zinc Sulfide

Scorch Control of Carboxylic Elastomers

1973 ◽  
Vol 46 (1) ◽  
pp. 78-95 ◽  
Author(s):  
V. L. Hallenbeck
Keyword(s):  
Zinc Oxide ◽  
Physical Properties ◽  
Shelf Life ◽  
Zinc Sulfide ◽  
Zinc Phosphate ◽  
Carboxyl Groups ◽  
Carboxyl Group ◽  
Phosphate Coating ◽  
Ionic Bond ◽  
Cure Temperature

Abstract Carboxylic elastomers can be cured by standard compounding recipes utilizing sulfur and zinc oxide. The zinc oxide, besides aiding the sulfur cure, also gives a secondary cure through an ionic bond with the carboxyl groups. However, because of the affinity of the zinc oxide for the carboxyl group, the stocks tend to have an excessive scorch and a short shelf life. To prevent this excessive scorch the zinc oxide must be isolated from the carboxyl group until the desired cure temperature is reached. Three materials may be used to isolate the zinc oxide : 1) zinc sulfide coated zinc oxide, 2) zinc phosphate coated zinc oxide and 3) metallic alkoxide combined with the zinc oxide. The use of any of these gives scorch control without affecting final physical properties. The amount of zinc sulfide coating, zinc phosphate coating, and metallic alkoxide varies with the type of carboxylic elastomer.

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.

Ellipsometric evaluation and morphology of mixed zinc sulfide/zinc oxide and zinc oxide nanostructures synthesized at various temperatures

2020 ◽  
Vol 98 (7) ◽  
pp. 689-694
Author(s):  
Mohammed S. Alqahtani ◽  
S.H. Mohamed ◽  
Z.A. Alrowaili ◽  
N.M.A. Hadia
Keyword(s):  
Zinc Oxide ◽  
Zinc Sulfide ◽  
Optical Constants ◽  
Calculated Data ◽  
Synthesis Temperature ◽  
Vapor Transport ◽  
Zinc Oxide Nanostructures ◽  
Oxide Nanostructures ◽  
Lower Oxygen ◽  
Device Applications

The aim of this work was to carry out systematic studies of how synthesis temperatures affect the morphology and properties of mixed zinc sulfide/zinc oxide (ZnSxOy and ZnO) nanostructures, and to get reliable data on optical constants of ZnSxOy and ZnO nanowires/nanobelts (NW/NB) for the use in device applications. ZnSxOy and ZnO NWs/NBs were fabricated using vapor transport in an open-end tube. Mixed ZnS0.47O0.62NWs was obtained at the synthesis temperature of 850 °C. The sulfur content disappeared as the temperature increased to 950 °C and 1050 °C and the morphology changed to a mixture of NW/NB. The NW prepared at 850 °C were indexed as mixed phases of hexagonal ZnS and hexagonal ZnO structures. The NW/NB prepared at 950 °C and 1050 °C were indexed as pure hexagonal ZnO structures. The thickness, surface roughness, and optical constants of the synthesized nanostructured samples were extracted from measurements of spectroscopic ellipsometry. A two-layers model was proposed to fit the calculated data to the measured ellipsometric spectra. The estimated band gap values of the prepared nanostructures lay 0.66–0.79 eV below the bulk ZnO value due to the lower oxygen content present in the samples and the stresses built in the samples during preparation.

An experimental study of anomalous x-ray scattering by zinc sulfide and zinc oxide

1959 ◽  
Vol 112 (1-6) ◽  
pp. 150-160 ◽  
Author(s):  
J. R. Townsend ◽  
G. A. Jeffrey ◽  
G. N. Panagis
Keyword(s):  
Experimental Study ◽  
Zinc Oxide ◽  
Zinc Sulfide ◽  
X Ray ◽  
X Ray Scattering ◽  
Ray Scattering
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