scholarly journals Quantitative Analysis of Free Sulfur Content in the Vulcanized Rubber by HPLC

2008 ◽  
Vol 81 (2) ◽  
pp. 39-43
Author(s):  
Kazumi NAKAYAMA ◽  
Tomoko WATANABE ◽  
Yoshito OHTAKE ◽  
Mutsuhisa Furukawa
Keyword(s):  
Quantitative Analysis ◽  
Sulfur Content ◽  
Vulcanized Rubber ◽  
Free Sulfur

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.

Monitoring Thermal Oxidation of Sulfur Crosslinks in SBR-Elastomers by Quantitative Analysis of Sulfur K-Edge XANES-Spectra

2001 ◽  
Vol 74 (2) ◽  
pp. 281-294 ◽  
Author(s):  
H. Modrow ◽  
J. Hormes ◽  
F. Visel ◽  
R. Zimmer
Keyword(s):  
Quantitative Analysis ◽  
Quantitative Description ◽  
Edge Structure ◽  
X Ray ◽  
Oxidative Aging ◽  
Vulcanized Rubber ◽  
Sample Composition ◽  
Aging Resistance ◽  
Oxidative Processes ◽  
X Ray Absorption

Abstract This paper presents a quantitative description of the processes occurring at the sulfur crosslinks of vulcanized rubber during thermo-oxidative aging. To extract this information in a nondestructive way, sulfur K-edge X-ray absorption near-edge structure (XANES) spectra have been analyzed quantitatively. We find that reversion takes place before the onset of oxidative processes at the sulfur bridges. Parallel to the oxidative processes, the production of cyclic sulfanes takes place. Both the relative and absolute contributions of the different reactions involving the sulfur crosslinks vary strongly with sample composition. Whereas antidegradants delay the thermo-oxidative aging without actually changing the aging resistance of the sulfur bonds, both the amount of S8/TBBS (N-tert-butylbenzothiazole-2-sulfenamide) and the presence of carbon black in the sample enhance this parameter considerably.

The "Free" Sulfur Content of Proteins

1967 ◽  
Vol 37 (11) ◽  
pp. 1004-1004
Author(s):  
C. Earland ◽  
D.J. Raven
Keyword(s):  
Sulfur Content ◽  
Free Sulfur

The Distribution of Combined Sulfur in Vulcanized Rubber and Its Bearing on the Sulfide Linkage Theory of Vulcanization

1939 ◽  
Vol 12 (2) ◽  
pp. 191-199
Author(s):  
I. Williams
Keyword(s):  
Physical Properties ◽  
Direct Evidence ◽  
Cross Linking ◽  
Direct Relation ◽  
Vulcanized Rubber ◽  
Free Sulfur

Abstract No direct evidence exists to support the sulfide linkage theory of vulcanization, which assumes that cross-linking of the molecules with sulfur would retain the elasticity and decrease the plasticity of the rubber. The following facts do not favor the sulfide linkage theory of vulcanization : (1) Vulcanized rubber can be peptized under conditions which do not appear to rupture a sulfide linkage. (2) No direct relation exists between the physical properties of vulcanized rubber and the amount of combined sulfur. (3) No direct relation exists between the ease of peptization and the physical properties of the vulcanizate. (4) Combined sulfur appears to assist the solvation of rubber. Rubber vulcanized with thiuram disulfides in the absence of free sulfur has poor physical properties but peptizes with difficulty. An increase in combined sulfur without a corresponding improvement in physical properties assists solvation. (5) Rubber having the best physical properties is also the most heterogeneous with respect to sulfur. The sulfide linkage theory would suggest that an even distribution of sulfur would produce the best physical properties. (6) Fractions of peptized vulcanizates, on evaporation of their solutions, leave insoluble vulcanized films, which shows that linkage by means of primary forces is unnecessary for producing the vulcanized condition.

The Determination of Free Sulfur in Soft Vulcanized Rubber by a Volumetric Method

1932 ◽  
Vol 5 (3) ◽  
pp. 360-362 ◽  
Author(s):  
W. D. Guppy
Keyword(s):  
Hydrogen Sulfide ◽  
Sulfuric Acid ◽  
Organic Compounds ◽  
Subsequent Oxidation ◽  
Vulcanized Rubber ◽  
Elementary State ◽  
Previously Treated ◽  
Mineral Sulfides ◽  
Free Sulfur

Abstract The methods so far proposed for the determination of the free sulfur in vulcanized rubber depend upon the removal of the sulfur by extraction of the rubber with hot acetone, and subsequent oxidation to sulfuric acid of the sulfur in the extract. The extract is liable however to contain, in addition to sulfur in the elementary state, organic compounds containing sulfur derived from the rubber resins, accelerator, or antioxidant. In the subsequent oxidation this sulfur will be oxidized to sulfuric acid to an extent which depends on the method of oxidation used. In the present work, a method of analysis has been developed which is more rapid than the existing methods, and in which it is considered that the determination of the sulfur present in the elementary state is less likely to be affected by organic compounds containing sulfur. It has been found that when vulcanized rubber placed in contact with a metal, such as tin or aluminum, is boiled in hydrochloric acid, hydrogen sulfide is generated by the action of the nascent hydrogen produced. This reaction occurred with rubber which had been previously treated with acid alone to decompose metallic sulfides, but no hydrogen sulfide was obtained from rubber which had been previously extracted with acetone and was free from metallic sulfides. As these results showed that the reactions were not due to the presence of mineral sulfides, or of sulfur combined with the rubber, it was concluded that the hydrogen sulfide was formed by the reduction of the free sulfur.

New Development in Rubber Reclaiming

1941 ◽  
Vol 14 (3) ◽  
pp. 717-723
Author(s):  
W. G. Essex
Keyword(s):  
Carbon Black ◽  
Milling Time ◽  
Steam Pressure ◽  
Raw Material ◽  
Manufacturing Cost ◽  
Pneumatic Motor ◽  
Vulcanized Rubber ◽  
New Development ◽  
History Of ◽  
Free Sulfur

Abstract The history of rubber reclaiming has been given by Alexander, and it is therefore intended only to make a brief reference to the well-known acid and alkali processes, the latter having proved to be by far the most successful method of reclaiming vulcanized rubber. The alkali process, introduced by Marks in 1899 had the outstanding advantage of simultaneously removing, from the waste, free sulfur, of which from 3 to 5 per cent was present, of destroying the fabric and of plasticizing the waste, this being accomplished by heating in a closed vessel under steam pressure with caustic soda. The acid process destroyed only the fabric, and plasticization by heat was performed in another operation in a separate vessel: by this method little or no free sulfur was removed from the waste. This latter disadvantage has since disappeared, for, with modern rubber compounding, there is little free sulfur left in vulcanized rubber. In recent years there have been widespread changes in the manufacture of rubber goods, particularly in the case of pneumatic motor tires, which are now the main source of raw material for reclaimed rubber. Organic accelerators, anti-oxidants and carbon black have made vulcanized rubber a very tough, resilient article, extremely resistant to aging and to heat, one of the chief agents used in rubber reclaiming. For example, modern motor tire treads, which are heavily reinforced with carbon black, are not so amenable to alkali and heat treatment, and tire treads reclaimed by this process have finally to be plasticized and made homogeneous by a much longer mechanical milling and refining treatment than was formerly necessary; in spite of this the treads still produce a proportion of rough, unrefinable material which has to be separated and rejected from the final reclaim. This increase in milling time, combined with lower finished production due to rejected unrefinable material, has had the effect of greatly increasing the manufacturing cost of the reclaim. Research was therefore started with the object of evolving a process which would successfully offset these difficulties caused by the changes in the properties and characteristics of the initial waste. The result of this work has been the creation of reclaimed rubber from which the disadvantages mentioned have been largely eliminated.

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