The Nature of Vulcanization Part IV

1929 ◽  
Vol 2 (3) ◽  
pp. 421-430
Author(s):  
H. P. Stevens ◽  
W. H. Stevens
Keyword(s):  
Zinc Oxide ◽  
Hydrogen Sulfide ◽  
Hydrochloric Acid ◽  
Zinc Sulfide ◽  
Low Temperatures ◽  
Sulfur Compounds ◽  
Zinc Salt ◽  
Acetone Vapor ◽  
Volatile Sulfur Compounds ◽  
Ether Mixture

Abstract (1) At low temperatures by means of accelerators it is possible to produce vulcanites containing “combined sulfur” considerably in excess of that required for the formula C5H8S. Such vulcanites may be obtained by vulcanizing at 100° with a variety of ultra-accelerators with and without zinc oxide as an activator. If zinc oxide or a zinc salt is used the excess coefficient cannot be explained by the presence of the zinc sulfide in the vulcanite. (2) The amount of sulfur combined with the rubber, given sufficient heating and presence of accelerator, is mainly dependent on the excess of sulfur present. (3) Extraction of the vulcanite with hydrochloric acid-ether mixture removes a part of the “combined” sulfur. A considerable amount is removed when the amount of combined sulfur is very large, but even then the amount of sulfur remaining is considerably in excess of that required by the formula C5H8S. (4) Vulcanization at low temperatures in solution in accordance with Whitby's procedure with the aid of accelerators also yields vulcanites with coefficients in excess of that required for the formula C5H8S. (5) The result of vulcanization at low temperatures is approximately the same, whether the rubber contains all the protein and serum ingredients, the usual proportion, or very little. (6) Extraction of sulfur from vulcanite with hot acetone vapor is not complete after 1210 hrs. (7) Having regard to the hydrogen sulfide and other volatile sulfur compounds evolved in appreciable quantities during vulcanization, it is evident that part of the combined sulfur results from substitution of hydrogen by sulfur. This substituted product is decomposed by the hydrochloric acid-ether mixture. It may not be possible to decompose the whole in this manner. Consequently, any “combined” sulfur in excess of that required by the formula C5H8S may result from substitution in the molecule.

The loss of volatile sulfur from sheep

1982 ◽  
Vol 33 (3) ◽  
pp. 585 ◽  
Author(s):  
K Kandylis ◽  
AC Bray
Keyword(s):  
Hydrogen Sulfide ◽  
Flow Rate ◽  
Sodium Sulfate ◽  
Sulfur Compounds ◽  
Volatile Sulfur Compounds ◽  
Gas Tight ◽  
Sulfur Balance ◽  
Volatile Sulfur

The losses of volatile sulfur compounds from sheep were investigated with sheep maintained on a high sulfur ration. The sheep were kept in metabolism cages in a 1-m3 gas-tight chamber with air drawn through the chamber and a trapping bath at a flow rate of 15 l/min. After the intraruminal administration of [35S]sodium sulfate, only minor quantities of 35S were found in the trapping bath over the following 8 h. It was concluded that volatile sulfur loss by eructation is negligible in the overall sulfur balance of the sheep. When [35S]hydrogen sulfide was released in the chamber, 50-80% of the 35S was recovered in the trapping bath in the subsequent 6 h.

Effect of Nitrogen Supplementation and Saccharomyces Species on Hydrogen Sulfide and Other Volatile Sulfur Compounds in Shiraz Fermentation and Wine

2009 ◽  
Vol 57 (11) ◽  
pp. 4948-4955 ◽  
Author(s):  
Maurizio Ugliano ◽  
Bruno Fedrizzi ◽  
Tracey Siebert ◽  
Brooke Travis ◽  
Franco Magno ◽  
...  
Keyword(s):  
Hydrogen Sulfide ◽  
Sulfur Compounds ◽  
Nitrogen Supplementation ◽  
Volatile Sulfur Compounds ◽  
Volatile Sulfur

Reactions between Compounding Ingredients during Vulcanization of Rubber

1941 ◽  
Vol 14 (1) ◽  
pp. 45-51
Author(s):  
E. C. B. Bott
Keyword(s):  
Zinc Oxide ◽  
Free Energy ◽  
Hydrogen Sulfide ◽  
Zinc Sulfide ◽  
Accelerated Aging ◽  
Lead Sulfate ◽  
Large Decrease ◽  
The Right

Abstract The calculations indicate that reactions (1), (3), and (5) can take place and proceed to virtual completion, whereas reactions (2) and (4) are not possible. They indicate also that the addition of extra sulfur to mixes containing litharge is necessary, and is in accordance with a custom long established empirically. It is evident that oxygen or nascent oxygen is not formed by any of these reactions; therefore no accelerated aging can take place by reactions between sulfur and litharge or zinc oxide. One peculiarity is that, although sulfur will react with litharge according to reaction (1), it appears that no oxygen is evolved by reaction (2), one possible reason being that the formation of lead sulfate takes place with a large decrease in free energy and is therefore readily formed. A possible explanation of the reaction between litharge and sulfur is that reaction (2), a possible first stage in reaction (1), is made to proceed to the right by the readiness with which lead sulfate can be formed. With respect to the reactions of zinc oxide, the assumption that zinc sulfide is formed by the action of hydrogen sulfide appears to be true.

The Reaction of Sulfur and Sulfur Compounds with Olefinic Substances. V. Rubber Vulcanization

1948 ◽  
Vol 21 (3) ◽  
pp. 543-552
Author(s):  
G. F. Bloomfield
Keyword(s):  
Zinc Oxide ◽  
Hydrogen Sulfide ◽  
Double Bond ◽  
Sulfur Atom ◽  
Small Proportion ◽  
Sulfur Compounds ◽  
Cross Linking ◽  
Inhibiting Effect ◽  
Mercapto Groups ◽  
Soluble Zinc

Abstract Data presented for a range of vulcanized rubbers prepared under different conditions show that, while olefinic unsaturation becomes reduced by vulcanization in the proportion of one double bond for each sulfur atom combined with a C5H8 unit, the original H/C ratio of 8/5 is not altered. The loss of unsaturation is somewhat modified when zinc oxide or certain accelerators also are present. Oxygen has a slight inhibiting effect on vulcanization; hydrogen sulfide and thiols markedly catalyse the vulcanization reaction without, apparently, affecting the efficiency of the sulfur cross-linking reaction. In confirmation of the results of Hull, Olsen, and France, a small proportion of zinc oxide or a soluble zinc soap promotes a reaction between sulfur and mercapto groups whereby di- and polysulfides are formed with liberation of hydrogen sulfide. The same type of activity is shown by some of the nitrogenous accelerators commonly used in rubber vulcanization. Substantial conversion of mercapto groups into polysulfide linkages is, therefore, to be expected when vulcanization is conducted in the presence of these auxiliary substances.

Stability of Volatile Sulfur Compounds (VSCs) in sampling bags – impact of temperature

2013 ◽  
Vol 68 (8) ◽  
pp. 1880-1887 ◽  
Author(s):  
H. Le ◽  
E. C. Sivret ◽  
G. Parcsi ◽  
R. M. Stuetz
Keyword(s):  
Hydrogen Sulfide ◽  
Waste Management ◽  
Dimethyl Sulfide ◽  
Agricultural Practices ◽  
Dimethyl Disulfide ◽  
Sulfur Compounds ◽  
Volatile Sulfur Compounds ◽  
Local Populations ◽  
And Storage ◽  
Volatile Sulfur

Volatile sulfur compounds (VSCs) are a major component of odorous emissions that can cause annoyance to local populations surrounding wastewater, waste management and agricultural practices. Odour collection and storage using sample bags can result in VSC losses due to sorption and leakage. Stability within 72 hour storage of VSC samples in three sampling bag materials (Tedlar, Mylar, Nalophan) was studied at three temperatures: 5, 20, and 30 °C. The VSC samples consisted of hydrogen sulfide (H2S), methanethiol (MeSH), ethanethiol (EtSH), dimethyl sulfide (DMS), tert-butanethiol (t-BuSH), ethylmethyl sulfide (EMS), 1-butanethiol (1-BuSH), dimethyl disulfide (DMDS), diethyl disulfide (DEDS), and dimethyl trisulfide (DMTS). The results for H2S showed that higher loss trend was clearly observed (46–50% at 24 hours) at 30 °C compared to the loss at 5 °C or 20 °C (of up to 27% at 24 hours) in all three bag materials. The same phenomenon was obtained for other thiols with the relative recoveries after a 24 hour period of 76–78% at 30 °C and 80–93% at 5 and 20 °C for MeSH; 77–80% at 30 °C and 79–95% at 5 and 20 °C for EtSH; 87–89% at 30 °C and 82–98% at 5 and 20 °C for t-BuSH; 61–73% at 30 °C and 76–98% at 5 and 20 °C for 1-BuSH. Results for other sulfides and disulfides (DMS, EMS, DMDS, DEDS) indicated stable relative recoveries with little dependency on temperature (83–103% after 24 hours). DMTS had clear loss trends (with relative recoveries of 74–87% in the three bag types after 24 hours) but showed minor differences in relative recoveries at 5, 20, and 30 °C.

Organic Sulfides and Polysulfides. VI. Reactions of Metallic Oxides with Polysulfide Rubbers

1958 ◽  
Vol 31 (3) ◽  
pp. 624-630
Author(s):  
Yuji Minoura
Keyword(s):  
Zinc Oxide ◽  
Hydrogen Sulfide ◽  
Zinc Sulfide ◽  
Lead Sulfide ◽  
Lead Oxide ◽  
High Polymer ◽  
Metallic Oxide ◽  
Metallic Oxides ◽  
Organic Sulfides

Abstract 1. Both mercaptides and disulfides were obtained by the reactions between benzyl mercaptan or tolyl mercaptan with zinc oxide or lead oxide. Qualitatively, mercaptides were formed from benzyl mercaptan easier than from tolyl mercaptan, and lead oxide reacted with mercaptan easier than zinc oxide with mercaptan. From the fact that no metallic sulfide was present, disulfides were likely formed from the oxidation of mercaptans by air. 2. The mono- or disulfides of the benzyl and tolyl series did not react with zinc oxide or lead oxide. 3. Neither tolyl tri- nor tetrasulfide reacted with zinc oxide, but benzyl tri- and tetrasulfide reacted with zinc oxide to give zinc sulfide. In the case of benzyl trisulfide, hydrogen sulfide, stilbene and benzaldehyde were formed, and in the case of tetrasulfide, we found the formation of hydrogen sulfide, stilbene, benzaldehyde and sulfur. 4. The tri- and tetrasulfide of both the benzyl and tolyl series reacted with lead oxide and they gave lead sulfide and organic disulfide. That is, they were desulfurized by lead oxide. In these reactions the benzyl series was more reactive than the tolyl series and the tetrasulfide was more reactive than trisulfide in the same series. 5. Lead oxide reacted with polysulfide easier than zinc oxide. 6. From the results of reactions between metallic oxide with mercaptan or other sulfide, it was concluded that the vulcanization mechanism of polysulfide rubber by metallic oxide is the reaction represented by Equations (1) to (4), the products being converted to high polymer without formation of a network of polysulfides.

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