Determination of Free Sulfur in Vulcanized Rubber

1942 ◽  
Vol 15 (2) ◽  
pp. 376-377
Author(s):  
J. G. Mackay ◽  
C. H. J. Avons
Keyword(s):  
Nitric Acid ◽  
Hydrochloric Acid ◽  
Barium Sulfate ◽  
Barium Chloride ◽  
Acetone Extract ◽  
Volumetric Method ◽  
Watch Glass ◽  
Rubber Industry ◽  
Vulcanized Rubber

Abstract The following comments pertain to a paper of the above title by Mackay and Avons, published in Transactions of the Institution of the Rubber Industry, Vol. 16, pages 117–122, October 1940, and reprinted in Rubber Chemistry and Technology, Vol. 14, pages 520–524, April 1941. H. P. Stevens draws attention to the penultimate paragraph on p. 522 in which it is pointed out that the bromine method of oxidation is tedious and the reagent unhealthful, whereas perchloric acid may be dangerous. As a result of many years experience he is of the opinion that neither reagent is necessary. After adding nitric acid to the acetone extract in the flask, which should be covered with a watch glass, and when the reaction has subsided, about 0.5 gram of potassium chlorate is added and the mixture kept warm at 50 to 60° C. The top of a water oven is convenient; but the heating must be limited, as the yellow oxides of chlorine are rapidly driven off near 100°, and the liquid changes back from yellow to orange. The flask can be left to itself for an hour or two, but further addition of chlorate may be necessary to complete the oxidation. The contents are evaporated to dryness and taken up twice with concentrated hydrochloric acid preparatory to precipitation with barium chloride. A volumetric method may be preferable when a large number of routine tests have to be made, otherwise the final estimation can be made as barium sulfate.

The Determination of Free Sulfur by a Volumetric Method Part II

1933 ◽  
Vol 6 (4) ◽  
pp. 512-517
Author(s):  
W. D. Guppy
Keyword(s):  
Hydrogen Sulfide ◽  
Organic Compounds ◽  
Sulfur Compounds ◽  
Acetone Extract ◽  
Volumetric Method ◽  
Organic Sulfur Compounds ◽  
Vulcanized Rubber ◽  
Volumetric Determination ◽  
Free Sulfur

Abstract 1. The method previously described for the volumetric determination of free sulfur in vulcanized rubber has been compared with the older gravimetric methods in cases where other organic compounds containing sulfur are present in the vulcanizate. 2. The volumetric method gave lower results than the methods involving oxidation of the acetone extract in the case of vulcanized rubber containing aldehydeamine condensation products of thiouram disulfide compounds. This indicated that the sulfur combined with some organic compounds was not reduced by the reagents used. 3. The results with the accelerator tetraethylthiouram disulfide showed that in some cases part of the sulfur in organic compounds was reduced under the conditions of the reaction. 4. The acetone-soluble and the acetone-insoluble portions of brown substitute contain organic sulfur compounds. Part of the sulfur in these compounds was reduced to hydrogen sulfide by the action of nascent hydrogen. 5. The sulfur compounds present in white substitute were stable toward the reducing agents used in the estimation of free sulfur. 6. The sulfur compounds formed by the vulcanization of ebonite were in part reduced to hydrogen sulfide with tin and acid. Variations in the composition of the mixing and in the vulcanizing conditions altered the amount of these reducible compounds. 7. The volumetric method previously described cannot be used for the determination of the free sulfur in ebonite, brown substitute or in vulcanized rubber containing brown substitute. In the case of vulcanized rubber containing brown substitute or of ebonite the method can be used to determine the amount of sulfur in the acetone extract. 8. The volumetric method can be employed for the determination of the free sulfur in soft vulcanized rubber containing white substitute and in reclaimed rubber.

Determination of Free Sulfur in Vulcanized Rubber

1941 ◽  
Vol 14 (2) ◽  
pp. 520-524
Author(s):  
J. G. Mackay ◽  
C. H. J. Avons
Keyword(s):  
Barium Chloride ◽  
American Chemical Society ◽  
Chemical Society ◽  
Acetone Extract ◽  
Vulcanized Rubber ◽  
Factory Production ◽  
Usual Manner ◽  
Physical And Chemical ◽  
Free Sulfur

Abstract In a rubber laboratory controlling uniformity of factory production by physical and chemical testing, free sulfur is perhaps the most important determination. In this investigation recently described methods for determining free sulfur have been compared. A previous examination by one of the present authors of various methods of estimating free sulfur led to the adoption of a procedure comprising oxidation of the dried acetone extract by a mixture of nitric acid, perchloric acid and bromine, followed by evaporation with sodium chloride and hydrochloric acid before precipitation of sulfate in the usual manner with barium chloride. In the Avon laboratories considerable use has also been made of the method recommended by the Rubber Division of the American Chemical Society, in which bromine alone is used to oxidize the acetone extract, and the sulfate so produced is estimated gravimetrically as the barium salt. Both methods are accurate, but they are not sufficiently quick for effective factory control. Meantime there had been published several new methods of determining free sulfur which were claimed to be quicker than the older procedures. With the aim, therefore, of finding a rapid method more suited to the requirements of a control laboratory, the following methods have been compared. Methods 1 and 2 below were included as controls. As test-samples, 22 different general rubber products selected from factory production were used. Each product contained at least one sulfur-bearing ingredient in addition to the sulfur added to effect vulcanization.

DETERMINATION OF TRACE AMOUNTS OF SILVER IN GALENA ORES

1960 ◽  
Vol 38 (9) ◽  
pp. 1488-1494 ◽  
Author(s):  
E. J. Bounsall ◽  
W. A. E. McBryde
Keyword(s):  
Aqueous Solution ◽  
Nitric Acid ◽  
Sodium Chloride ◽  
Hydrochloric Acid ◽  
Chloride Solution ◽  
Sodium Chloride Solution ◽  
Silver Content ◽  
Aqueous Sodium Chloride Solution ◽  
Aqueous Sodium

An analytical method is described for the determination of microgram amounts of silver in galena ores, based on the "reversion" of silver dithizonate. Silver is separated from relatively large amounts of lead by extraction as dithizonate into chloroform from an aqueous 1:99 nitric acid solution. Separation from mercury, which is also extracted under these conditions and would, if present, interfere in the analysis, is achieved by reverting the dithizonate solution with a 5% aqueous sodium chloride solution which is also 0.015 molar in hydrochloric acid. Following dilution of this aqueous solution and adjustment of pH, silver is again extracted into chloroform as the dithizonate, and determined absorptiometrically. Analyses of a number of galena ore samples showed a precision of within 3% for a silver content ranging from 0.03 to 0.4%.Some other methods for isolating silver from these samples, which were tried but found unsatisfactory, are discussed.

The Effects of Acidic Medium on the Sodium Contents Determination by FAAS

2020 ◽  
Vol 1001 ◽  
pp. 139-144
Author(s):  
Ying Li ◽  
Ben Tao Li ◽  
Guang Yu Sun ◽  
Hui Huang ◽  
Chen Gong ◽  
...  
Keyword(s):  
Nitric Acid ◽  
Hydrochloric Acid ◽  
Atomic Absorption Spectrometry ◽  
Flame Atomic Absorption Spectrometry ◽  
Perchloric Acid ◽  
Acidic Medium ◽  
Absorption Spectrometry ◽  
Flame Atomic Absorption ◽  
Acid Effect

The influence of different acidic medium, including hydrochloric acid, nitric acid and perchloric acid on the absorbance of sodium by flame atomic absorption spectrometry was studied. The results showed that the effects of acidic medium and water on the determination of sodium were as follows: hydrochloric acid > perchloric acid > nitric acid > water. Acid effect changed with the increase of acid concentration, however, the absorbance value of sodium element decreased when the concentration of acid was higher than 1%~2%. This effect was more obvious for high content of sodium. The detection limits, repeatability and recovery of the samples under the three acidic medium were compared. The optimum acid conditions were determined and the sensitivity of the method was improved.

Determination of Sulfur in Rubber Compounds. I. Precipitation of Barium Sulfate in the Presence of Picric Acid

1936 ◽  
Vol 9 (4) ◽  
pp. 648-660
Author(s):  
C. Herbert Lindsly
Keyword(s):  
Barium Sulfate ◽  
General Procedure ◽  
Picric Acid ◽  
Barium Chloride ◽  
Sulfate Solution ◽  
Rubber Compounds ◽  
Precipitation Procedure ◽  
Barium Chloride Solution ◽  
Made In

Abstract THERE is probably no single operation in analytical chemistry that has received more attention from investigators than that of precipitation of barium sulfate by means of a soluble barium salt for the determination of sulfate or of barium. The literature on this subject is voluminous and the conclusions reached by different investigators as to the proper procedure to employ in order to obtain a precipitate which will be filterable and reasonably pure are highly contradictory. The procedure which seems to be in most general use at present for the determination of sulfate is that of adding the barium chloride solution to the hot sulfate solution very slowly, stirring vigorously meanwhile, then allowing the whole to digest at an elevated temperature for several hours before filtering. The diversity of opinion as to the proper procedure arises, the author believes, from the fact that the barium sulfate precipitate is exceedingly sensitive to its environment and that a very slight change in the amount or kind of impurities present in the solutions during precipitation has a profound effect upon the crystal size and shape of the precipitated particles as well as upon their purity. Kolthoff and Vogelenzang (2) have stated that it is impossible to prescribe a general procedure for the accurate precipitation of sulfate in arbitrary mixtures. In other words, a precipitation procedure which gives satisfactory results in the determination of sulfur in copper ores, for instance, may not yield a satisfactory precipitate when applied to the determination of total sulfur in hard rubber dust, and a study of each type of determination, with due consideration for the amount and kind of impurities present, must be made in order to find the conditions necessary to obtain a precipitate which is pure and easily filterable.

Determination of Total Sulfur in Vulcanized Rubber Mixtures

1952 ◽  
Vol 25 (2) ◽  
pp. 371-374 ◽  
Author(s):  
Horst Frey
Keyword(s):  
Iron Oxide ◽  
Ion Exchange ◽  
Barium Sulfate ◽  
Aqueous Sodium Hydroxide ◽  
Total Sulfur ◽  
Aqueous Sodium ◽  
Vulcanized Rubber ◽  
Exchange Agent ◽  
Volumetric Methods

Abstract A method is described, which, by means of a resin ion-exchange agent, makes possible the elimination of the disturbing effects of foreign cations, particularly iron and chromium, in the determination of the total sulfur in vulcanized rubber mixtures. By this procedure, rapid volumetric methods for determining sulfate, even in the analysis of mixtures containing iron oxide or chromium oxide pigments, can be utilized. The procedure involves precipitation of the sulfate by benzidine and determination by titration with aqueous sodium hydroxide. The method is more rapid and more reliable than ordinary gravimetric methods involving precipitation of barium sulfate.

The Polarographic Determination of Organic Accelerators of Vulcanization

1941 ◽  
Vol 14 (4) ◽  
pp. 914-919 ◽  
Author(s):  
Gerard Proske
Keyword(s):  
Double Bond ◽  
Organic Compounds ◽  
Analytical Determination ◽  
Polarographic Method ◽  
Rubber Industry ◽  
Vulcanized Rubber ◽  
Color Reactions ◽  
Analytical Utility ◽  
Kjeldahl Nitrogen

Abstract In spite of the great importance which vulcanization accelerators have attained in the rubber industry, there is still an almost complete lack of analytical methods, both for determining the accelerator contents of rubber mixtures and for identifying accelerators in vulcanized rubber. Apart from the wholly unsatisfactory and uncertain method of deciding the existence of organic accelerators in vulcanized rubber by a Kjeldahl nitrogen determination, there is little of value in the literature. Twiss and Martin have described a few qualitative reactions of accelerators. Recently Shimada described some color reactions of accelerators with cobalt oleate, but the analytical utility of these reactions is very doubtful. Of far more promise than these is the polarographic method, the value of which in the analytical determination of a series of important accelerators was proved in an investigation which will be described in the present paper. It had already been proved in earlier polarographic investigations that organic compounds containing nitrogen with a double bond can be reduced electrolytically, provided groups with a tendency to rupture are close to the double bond. Shikata and Tachi have shown this to be true of azobenzene, and Winkel and Proske of dimethylquinoxaline.

Determination of Free Carbon in Rubber. The Cresol Method

1941 ◽  
Vol 14 (1) ◽  
pp. 241-248 ◽  
Author(s):  
J. B. Roberts
Keyword(s):  
United States ◽  
Nitric Acid ◽  
Carbon Content ◽  
Accurate Method ◽  
The United States ◽  
Free Carbon ◽  
Simple Apparatus ◽  
Vulcanized Rubber ◽  
Acid Method

Abstract A simple, accurate method for the determination of free carbon in either raw or vulcanized rubber is presented. It has replaced the nitric acid method entirely in the laboratory of the United States Rubber Company, Detroit, Michigan. A study of the effects of interfering substances, and numerous comparisons of results by the cresol and the nitric acid methods, are given. Results by the cresol method, in the absence of interfering substances, are within 1 per cent of the calculated free carbon content. The method requires only simple apparatus readily available.

scholarly journals A volumetric method for the determination of tetranitromethane in concentrated nitric acid

1957 ◽  
Vol 6 (10) ◽  
pp. 626-630
Author(s):  
Isamu SAKAMAKI ◽  
Hajime ISHIKAWA ◽  
Rikio NAKAMURA
Keyword(s):  
Nitric Acid ◽  
Volumetric Method
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