Vulcanization of GR-S by the Peachey Process

1947 ◽  
Vol 20 (1) ◽  
pp. 182-183
Author(s):  
Archibald T. McPherson
Keyword(s):  
Hydrogen Sulfide ◽  
Sulfur Dioxide ◽  
Natural Rubber ◽  
Glass Tube ◽  
The Other ◽  
Curing Process ◽  
Sulfide Sulfur ◽  
Simple Apparatus ◽  
Synthetic Rubber

Abstract It has been found possible to vulcanize GR-S synthetic rubber by subjecting it alternately to hydrogen sulfide and sulfur dioxide gases. This method for curing, known as the Peachey process, was used for natural rubber as long ago as 1921. A simple apparatus was constructed, in which strips of thinly milled rubber were placed on a screen inside a glass tube. One end of this tube was attached to valves connecting it to tanks of hydrogen sulfide, sulfur dioxide, and air, respectively. The other end of the tube led to a series of traps containing solutions which absorbed or destroyed the gases. For each test performed, natural rubber samples were placed inside the tube along with the GR-S samples for comparison. Each strip was weighed before it was inserted in the apparatus. Hydrogen sulfide was first slowly passed over the samples for a period of five minutes. Then air was blown through for a few seconds—just long enough to free the surroundings from the sulfide gas, but not long enough for the gas to be lost from solution in the rubber. Sulfur dioxide gas was next admitted and allowed to pass over the samples for five minutes. A subsequent short sweep of air through the tube completed one cycle of the curing process.

Studies of the Vulcanization of Rubber. X. The Vulcanization of Natural Rubber with a Mixture of Sulfur Dioxide and Hydrogen Sulfide

1953 ◽  
Vol 26 (3) ◽  
pp. 559-566 ◽  
Author(s):  
B. A. Dogadkin ◽  
F. Keifetz
Keyword(s):  
Tensile Strength ◽  
Hydrogen Sulfide ◽  
Sulfur Dioxide ◽  
Natural Rubber ◽  
Sulfur Content ◽  
Spatial Network ◽  
Smooth Curves ◽  
Multiple Cycles

Abstract 1. The dynamics of the changes of the properties of rubber during vulcanization by a mixture of sulfur dioxide and hydrogen sulfide, in distinction from conventional vulcanization by sulfur, is expressed by smooth curves. No vulcanization optimum is observed. 2. With multiple cycles of vulcanization, the increase of bound sulfur content above 3 per cent results in a decrease of tensile strength. 3. Changes of tensile strength of the vulcanizate dependent on changes of sulfur content are attributable to the influence of the density of the spatial network on the orientation processes during deformation.

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.

scholarly journals Water vapor inhibits hydrogen sulfide detection in pulsed fluorescence sulfur monitors

2016 ◽  
Vol 9 (6) ◽  
pp. 2669-2673 ◽  
Author(s):  
Anders B. Bluhme ◽  
Jonas L. Ingemar ◽  
Carl Meusinger ◽  
Matthew S. Johnson
Keyword(s):  
Hydrogen Sulfide ◽  
Water Vapor ◽  
Sulfur Dioxide ◽  
Relative Humidity ◽  
Pollution Control ◽  
Sulfide Sulfur ◽  
Molybdenum Catalyst ◽  
Air Stream ◽  
Ambient Concentrations ◽  
Converter Unit

Abstract. The Thermo Scientific 450 Hydrogen Sulfide–Sulfur Dioxide Analyzer measures both hydrogen sulfide (H2S) and sulfur dioxide (SO2). Sulfur dioxide is measured by pulsed fluorescence, while H2S is converted to SO2 with a molybdenum catalyst prior to detection. The 450 is widely used to measure ambient concentrations, e.g., for emissions monitoring and pollution control. An air stream with a constant H2S concentration was generated and the output of the analyzer recorded as a function of relative humidity (RH). The analyzer underreported H2S as soon as the relative humidity was increased. The fraction of undetected H2S increased from 8.3 at 5.3 % RH (294 K) to over 34 % at RH  >  80 %. Hydrogen sulfide mole fractions of 573, 1142, and 5145 ppb were tested. The findings indicate that previous results obtained with instruments using similar catalysts should be re-evaluated to correct for interference from water vapor. It is suspected that water decreases the efficiency of the converter unit and thereby reduces the measured H2S concentration.

scholarly journals Water Vapor Inhibits Hydrogen Sulfide Detection in Pulsed Fluorescence Sulfur Monitors

2016 ◽  
Author(s):  
Anders B. Bluhme ◽  
Jonas L. Ingemar ◽  
Carl Meusinger ◽  
Matthew S. Johnson
Keyword(s):  
Hydrogen Sulfide ◽  
Water Vapor ◽  
Sulfur Dioxide ◽  
Relative Humidity ◽  
Pollution Control ◽  
Sulfide Sulfur ◽  
Molybdenum Catalyst ◽  
Air Stream ◽  
Ambient Concentrations ◽  
Converter Unit

Abstract. The Thermo Scientific 450 Hydrogen Sulfide - Sulfur Dioxide Analyzer measures both H2S and SO2. SO2 is measured by pulsed fluorescence, while H2S is converted to SO2 with a molybdenum catalyst prior to detection. The 450 is widely used to measure ambient concentrations, e.g. for emissions monitoring and pollution control. An air stream with a constant H2S concentration was generated and the output of the analyzer recorded as a function of relative humidity. The analyzer under-reported H2S as soon as the relative humidity was increased. The fraction of undetected H2S increased from 8.3 % at 5.3 % RH (294 K) to over 34 % at RH > 80 %. H2S mole fractions of 573, 1142, and 5145 ppb were tested. The findings indicate that previous results obtained with instruments using similar catalysts should be re-evaluated to correct for interference from water vapor. It is suspected that water decreases the efficiency of the converter unit and thereby reduces the measured H2S concentration.

Vistanex Polybutene—Rubber Blends

1941 ◽  
Vol 14 (2) ◽  
pp. 386-397 ◽  
Author(s):  
S. Longman
Keyword(s):  
Natural Rubber ◽  
Raw Materials ◽  
Petroleum Products ◽  
The Other ◽  
Partial Substitution ◽  
Manufacturing Equipment ◽  
Rubber Industry ◽  
Rubber Blends ◽  
Synthetic Rubber

Abstract From the foregoing data on blends of Vistanex Polybutene and rubber, it is evident that these two materials complement one another. Each has properties which the other lacks, and blends of the two can be made to emphasize the more desirable properties of either one. Extreme flexibility in compounding these blends is possible, since they are perfectly compatible in milled compounds. Therefore, great latitude is given in compounding of these blends to secure any range or degree of properties possible with either of the components. Vistanex Polybutenes should not be considered as synthetic rubber, because they will not vulcanize, and they lack certain characteristics of vulcanized natural rubber. More properly Vistanex Polybutenes should be considered as modifying agents for partial substitution of natural rubber. In many cases, this substitution of a part of the natural rubber in a compound by Vistanex Polybutene confers definite advantages and improves qualities of such compounds for special uses. Therefore, Polybutenes, even in normal times, have a very definite field of usefulness and, in the event that imports of natural rubber become restricted, the availability of the Vistanex Polybutenes in quantity will be of increasing importance to the rubber industry. Since the raw materials for the manufacture of Vistanex Polybutene are petroleum products, the availability of raw materials is a source of no difficulty in this country. Likewise, the manufacturing equipment is not excessively expensive, and, with expanded production, lowered prices may confidently be expected.

The Formation of Sulfur from Hydrogen Sulfide and Sulfur Dioxide. A Contribution to the Vulcanization Process of Peachey

1934 ◽  
Vol 7 (4) ◽  
pp. 637-640
Author(s):  
Lothar Hock ◽  
Hans Schmidt
Keyword(s):  
Hydrogen Sulfide ◽  
Sulfur Dioxide ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Decisive Role ◽  
The Other ◽  
General Reaction ◽  
Series Of Experiments ◽  
Vulcanization Process ◽  
Insight Into

Abstract In the reduction of sulfur dioxide by hydrogen sulfide, the course of the reaction depends wholly upon whether water is present or the gases are dry. With water present, there is a ready separation of sulfur, even at room temperature, according to the general reaction: SO2+2H2S→3S+2H2O, though accompanied by more complicated reactions involving the formation of polythionic acids. On the contrary at room temperature the dried gases do not react, and only at elevated temperatures do they give rise to sulfur and water vapor, in which case because the reaction is exothermic the equilibrium is displaced more and more toward the original sulfur dioxide and hydrogen sulfide. Conversely then, the formation of free sulfur is favored by lowering the temperature. The heat of activation of the reaction is however so great, even at room temperature, that the rate of the reaction is imperceptibly small, and accordingly no reaction is observable. In the presence of rubber, on the other hand, conditions are extremely favorable for activation, because the rubber hydrocarbon plays the part of an acceptor of the liberated sulfur and is vulcanized by it, as Peachey and Skipsey were able to show in their well-known work. The question then arises whether, in this form of vulcanization, the water which is already present or which is formed plays a decisive role in starting and continuing the reaction (in which case the formation of polythionic acids might also play a part), or whether the essential reaction takes place between the two gases in the dry state, in which case the reaction progresses in a much more unrestrained way than in the absence of substances which activate the reaction. In view of this, two series of experiments were planned with the object of obtaining a better insight into the reaction. In one series the rate of the reaction with both gases in the dry state was studied by some trial measurements only; in the other series the part played by moisture in vulcanization by the Peachey process and in the vulcanization of rubber swollen in benzene was investigated.

Destructive Hydrogenation of High-Molecular-Weight Polymers. Isobutene Polymer, Butadiene Polymer, and Natural Rubber

1940 ◽  
Vol 13 (4) ◽  
pp. 849-855
Author(s):  
Vladimir N. Ipatieff ◽  
Raymond E. Schaad
Keyword(s):  
Molecular Weight ◽  
Natural Rubber ◽  
Nickel Oxide ◽  
The Other ◽  
Large Molecules ◽  
Synthetic Rubber ◽  
Destructive Hydrogenation ◽  
Future Publication ◽  
Proper Interpretation ◽  
Naphthenic Hydrocarbons

Abstract Destructive hydrogenation under pressure in the presence of nickel oxide and molybdenum oxide has been used to show the presence of naphthenic hydrocarbons in high-boiling olefin polymer. It was of interest to apply this tool to other hydrocarbons having large molecules, especially rubber and synthetic rubber like polymers. The destructive hydrogenation of isobutene polymer yielded only paraffinic hydrocarbons, including isobutane in the gases. Butadiene polymer, on the other hand, gave only naphthenic products, chiefly ethylcyclohexane and a dicyclic hydrocarbon. Similarly, natural rubber yielded only naphthenes, with p-methylisopropylcyclohexane as the major component of the lower boiling portion of the product. Isoprene, under the conditions used for the destructive hydrogenation of the rubber, yielded isopentane and an unsaturated naphthene, i. e., a hydropolymer of isoprene, which was converted into p-methylisopropylcyclohexane by further hydrogenation. Discussion of the relation of these results to the structures of the polymeric substances hydrogenated is reserved for a future publication of further work now in progress undertaken to aid in the proper interpretation of the above indicated experiments.

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