Determination of Sulfur in Rubber Vulcanizates

1956 ◽  
Vol 29 (2) ◽  
pp. 612-619 ◽  
Author(s):  
E. W. Zimmerman ◽  
V. E. Hart ◽  
Emanuel Horowitz
Keyword(s):  
Nitric Acid ◽  
Barium Sulfate ◽  
Combustion Method ◽  
Fusion Method ◽  
Total Sulfur ◽  
A Value ◽  
Acid Method ◽  
Barium Compounds ◽  
Good Agreement

Abstract A combustion method for rubber which determines the sulfur evolved at 480° to 500° C is compared with the fusion and the zinc-nitric acid methods. In the combustion method an interaction occurs between sulfur and fillers present in the rubber. The effect of particular fillers with respect to this interaction is discussed. A value representative of the organically bound sulfur in an extracted specimen can be obtained by the combustion method when no reaction takes place between the sulfur and the fillers during combustion. The fusion method yields results in good agreement with the total sulfur added in compounding the rubber samples. Except in the presence of barium compounds, the zinc-nitric acid method likewise determines total sulfur. When barium compounds are present, barium sulfate is formed during the oxidation, and low values are obtained for the total sulfur.

Turbidimetry of inorganic sulfate, ester sulfate, and total sulfur in urine.

1980 ◽  
Vol 26 (8) ◽  
pp. 1178-1181 ◽  
Author(s):  
P Lundquist ◽  
J Mårtensson ◽  
B Sörbo ◽  
S Ohman
Keyword(s):  
Polyethylene Glycol ◽  
Nitric Acid ◽  
Perchloric Acid ◽  
Barium Sulfate ◽  
Wet Oxidation ◽  
Total Sulfur ◽  
Sulfate Ester ◽  
Healthy Persons ◽  
Inorganic Sulfate

Abstract We describe simple and precise methods for the determination of inorganic sulfate, ester sulfate, and total sulfur in urine. The methods are based on turbidimetry of sulfate as barium sulfate in the presence of a small amount of preformed barium sulfate and with polyethylene glycol as a stabilizing agent. Inorganic sulfate is directly determined, whereas ester sulfate is measured after removal of inorganic sulfate, followed by acid hydrolysis. Total sulfur is determined after wet oxidation of the sample with nitric acid and perchloric acid in the presence of vanadate as a catalyst. We also report excretion values for healthy persons on a self-selected diet. Men excrete significantly higher amounts of inorganic sulfate and total sulfur than women, but this sex-related difference becomes insignificant if excretion values are expressed relative to creatinine.

Comparison of the Bromine and Nitric Acid Methods of Estimating Sulfur in Acetone Extracts

1947 ◽  
Vol 20 (1) ◽  
pp. 315-319 ◽  
Author(s):  
J. F. Morley ◽  
J. R. Scott
Keyword(s):  
Nitric Acid ◽  
Sulfur Content ◽  
Elementary Sulfur ◽  
Total Sulfur ◽  
Total Sulfur Content ◽  
Acid Method ◽  
The Difference ◽  
The One ◽  
Acetone Extracts ◽  
Free Sulfur

Abstract From the experiments described, it appears that neither the bromine method nor the nitric acid method is perfectly satisfactory, for the following reasons. (1) Neither method gives the true free sulfur in rubbers containing sulfur-bearing accelerators, as these cause positive errors of anything up to 0.2–0.3 per cent. (2) The nitric acid method does not give the true free sulfur in rubbers, without sulfur-bearing accelerators, because the result includes some of the sulfur combined with the rubber “resins” the tests do not show definitely whether this applies also to the bromine method. (3) Neither method gives the total sulfur in the acetone extract, since some of the sulfur combined with the “resins” is not included in the result; the presence of certain sulfur-bearing accelerators increases the error. The statement previously referred to (loc. cit.), that the bromine method approximates more nearly to the elementary sulfur content and the nitric acid method more nearly to the total sulfur content of the extract, appears to be a correct generalization. In most cases, however, the difference between the results obtained by the two methods would be less than 0.1 per cent. In respect of simplicity and rapidity of working, the bromine method has the advantage over the nitric acid method, and therefore in all ordinary circumstances is the one to be recommended.

Device Modeling of a-Si:H Alloy Solar Cells: Calibration Procedure for Determination of Model Input Parameters

1998 ◽  
Vol 507 ◽  
Author(s):  
M. Zeman ◽  
R.A.C.M.M. Van Swaaij ◽  
E. Schroten ◽  
L.L.A. Vosteen ◽  
J.W. Metselaar
Keyword(s):  
Solar Cell ◽  
Material Properties ◽  
Calibration Procedure ◽  
Model Parameters ◽  
Model Input ◽  
A Value ◽  
Input Parameters ◽  
Simulated Material ◽  
Good Agreement

ABSTRACTA calibration procedure for determining the model input parameters of standard a-Si:H layers, which comprise a single junction a-Si:H solar cell, is presented. The calibration procedure consists of: i) deposition of the separate layers, ii) measurement of the material properties, iii) fitting the model parameters to match the measured properties, iv) simulation of test devices and comparison with experimental results. The inverse modeling procedure was used to extract values of the most influential model parameters by fitting the simulated material properties to the measured ones. In case of doped layers the extracted values of the characteristic energies of exponentially decaying tail states are much higher than the values reported in literature. Using the extracted values of model parameters a good agreement between the measured and calculated characteristics of a reference solar cell was reached. The presented procedure could not solve directly an important issue concerning a value of the mobility gap in a-Si:H alloys.

Measurement of the Isothermal Volume Dilation Accompanying the Unilateral Extension of Rubber

1959 ◽  
Vol 32 (2) ◽  
pp. 428-433
Author(s):  
Fred G. Hewitt ◽  
Robert L. Anthony
Keyword(s):  
Molecular Weight ◽  
Young’S Modulus ◽  
Experimental Results ◽  
Molecular Weights ◽  
Rubber Specimen ◽  
A Value ◽  
Fractional Increase ◽  
Internal Agreement ◽  
Good Agreement

Abstract The fractional increase in volume accompanying the isothermal extension of soft gum rubber was measured for four rubber samples at mean extensions of 14, 33, and 51%. The chain molecular weights Mc of the four samples were 5500, 5100, 4400, and 3000, with an estimated uncertainty of about 10% in each value of Mc. The observed fractional increase in volume ranged from 3.2×10−5 to 142×10−5, the latter value being observed for the sample of lowest chain molecular weight and at the extension of 51%. The experimental results for each sample have been represented by theoretical curves based on Gee's expression for the fractional increase in volume as a function of the sample extension. The theoretical curves exhibit good agreement with those of Gee, Stern, and Treloar. The process of fitting the theoretical curves to the experimental points constituted a determination of Young's modulus E for each rubber specimen. As a check on the experimental results, and also on the theory employed, determinations of E were also made by two additional methods, namely, from rough stess-strain curves, and from the relation E=3γρRT/Mc. With one exception, the internal agreement between the three determinations of E for the four different samples was satisfactory. The exception noted can probably be ascribed to the use of too small a value of Mc for the sample of lowest chain molecular weight.

Determination of ΔHf2980(C6F5Br, g) from studies of the combustion of bromopentafluorobenzene in oxygen and calculation of D[C6F5 — Br]

1977 ◽  
Vol 55 (24) ◽  
pp. 4222-4226 ◽  
Author(s):  
Michael J. Krech ◽  
Stanley James W. Price ◽  
Henry J. Sapiano
Keyword(s):  
Material Balance ◽  
Combustion Method ◽  
Heat Of Formation ◽  
Molar Ratio ◽  
Direct Combustion ◽  
A Value ◽  
Fold Excess

The heat of formation of bromopentafluorobenzene has been determined through the use of the direct combustion method which has been applied to hexafluorobenzene, octafluorotoluene, and iodopentafluorobenzene. While a platinum lined bomb is normally used for these types of compounds a steel bomb had to be adopted in this work. The combustion of bromopentafluorobenzene in the steel bomb yields CO2, CF4, F2, Br2, and BrF3. With a ten-fold excess of oxygen, the average CO2 to CF4 molar ratio is 7.29 ± 0.07. A material balance was obtained for carbon, fluorine, and bromine. The value of ΔHf2980(C6F5Br, g) = −711.6 ± 16.7 kJ mol−1 (−170.1 ± 4.0 kcal mol−1) has been combined with ΔHf2980(C6F5, g) = −387.4 kJ mol−1 (−92.6 kcal mol−1) and ΔHf2980(Br, g) = 111.7 kJ mol−1 (26.7 kcal mol−1) to obtain a value for D[C6F5—Br] of 435.9 kJ mol−1 (104.2 kcal mol−1).

Determination of Forces in a Magnetic Bearing Actuator: Numerical Computation With Comparison to Experiment

1992 ◽  
Vol 114 (4) ◽  
pp. 796-801 ◽  
Author(s):  
J. D. Knight ◽  
Z. Xia ◽  
E. McCaul ◽  
H. Hacker
Keyword(s):  
Relative Permeability ◽  
Free Space ◽  
Flux Distribution ◽  
Magnetic Bearing ◽  
Two Dimensional ◽  
Metal Parts ◽  
A Value ◽  
Axis Of Symmetry ◽  
Good Agreement

Calculations of the forces exerted on a journal by a magnetic bearing actuator are presented, along with comparisons to experimentally measured forces. The calculations are based on two-dimensional solutions for the flux distribution in the metal parts and free space, using finite but constant permeability in the metals. Above a relative permeability of 104 the effects of changes in permeability are negligible, but below 104 decreases in permeability cause significant decreases in the force. The calculated forces are shown to depend on the metal permeability more strongly when the journal is displaced from its centered position. The predicted forces in the principal attractive direction are in good agreement with experiment when a relatively low value of permeability is chosen. The forces measured normal to the axis of symmetry when the journal is displaced from that axis, however, are significantly higher than predicted by theory, even with a value of relative permeability larger than 5000. These results indicate a need for futher work including nonlinear permeability distributions.

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.

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 Extraction and Determination of Various Precipitates in Steel by Cold Nitric Acid Method

1972 ◽  
Vol 58 (14) ◽  
pp. 2067-2077 ◽  
Author(s):  
Kazuo KAWAMURA ◽  
Shiro WATANABE ◽  
Tokio SUZUKI
Keyword(s):  
Nitric Acid ◽  
Acid Method
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