Reactions of Accelerators during Vulcanization - VI. Organic Acids and Inorganic Accelorators

Bedford, C. W.; Winkelmann, H. A.

doi:10.1021/ie50169a013

Cited by 5 publications

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“…The rubber and pigments were standardized in regard to chemical and physical properties and the various compounds prepared under the same milling conditions. Uncured compounds were studied microscopically Note-In general, this consisted of breaking down 400 grams of rubber for 4 minutes on 12-inch (30-cm.) laboratory mills, adding the pigments and sulfur as quickly as possible, and then sheeting off to 100 gage.…”

Section: Methodsmentioning

confidence: 99%

Dispersion of Pigments in Rubber¹: I—Microscopical Studies of Agglomeration and Flocculation

Grenquist¹

1928

Ind. Eng. Chem.

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Section: Methodsmentioning

confidence: 99%

Dispersion of Pigments in Rubber¹: I—Microscopical Studies of Agglomeration and Flocculation

Grenquist¹

1928

Ind. Eng. Chem.

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“…Basic Industries-Basic industries whose raw material is, for the most part, not processed and whose products in the main are the raw materials for other industries must, to succeed, locate near cheap fuel or cheap power. It is true that major raw materials must be obtainable (1) advantageously as to quality and price, or at least (2) on a competitive basis with the same industries in other localities; but these two factors alone will not serve to establish a basic industry, for basic industries demand cheap fuel and advantageous raw materials in order to compete in the national market. It is…”

Section: Inmentioning

confidence: 99%

Stearic Acid in Litharge-Cured Rubber Compounds

Sheppard¹

1929

Ind. Eng. Chem.

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provement. This has been found to be true. In compounds containing substantial amounts of alkali process reclaim, a low sulfur and a high accelerator ratio, there is sometimes a rapid reversion causing blowing after the proper cure has been reached. Compounds containing stearic acid show less tendency to reversion under these conditions than compounds containing other softeners. Conclusions1-Stearic acid does not compare with other softeners in plasticizing efficiency when used in contact with vulcanized rubber scrap during devulcanization.2-Stearic acid when added as a softener to devulcanized scrap on the mill prior to refining imparts properties which are very desirable. (a) Makes the reclaim batch more plastic, (b) improves tubing and calendering properties, (c) reduces nerve without production of excess tack, (d) improves curing properties (higher tensile strength, higher modulus, and improved molding properties) of reclaimed rubber, ( e ) when pigments are added it gives better dispersion with improved physical properties.3-Stearic acid when used in compounds containing reclaimed rubber improves the curing properties of these compounds.T HAS been known at least since 1912 that the resins present in crude rubber are essential to vulcanization with litharge. I n that year Weber ( 4 ) reported that deresinated rubber mill not cure and concluded that "resins play an active part in the vulcanization;" but he formulated no theory of the way in which they function. At that time the composition of the rubber resins was not so well known as now. I n 1916 Stevens (3) verified Weber's conclusions, but believed his findings supported the Esch and Auerbach ( 2 ) theory that litharge accelerated vulcanization through the rise in temperature occasioned by an exothermal reaction.It is now well understood that resins promote vulcanization through their content of organic acid. It was proposed by Bedford and Winkelmann (1) in 1924 that litharge vulcanization proreeds by the following steps: (a) reaction of lead oxide with an organic acid (naturally present in the resin or added during the mixing) to form a rubber-soluble soap; (b) reaction of the lead soap with hydrogen sulfide to form a hydrosulfide salt or a hydrosulfide; (c) reaction of the latter with sulfur to form a disulfide and then a polysulfide; (d) decomposition of the (unstable) polysulfide to yield a very active form of sulfur-the ultimate vulcanizer. The polysulfide theory has been generally accepted as accounting adequately for the known facts.It is clear, then, that the efficiency of litharge as an accelerator is absolutely dependent upon the existence of an organic acid in the rubber as mixed. The mere statement of this general principle, however, by no means gives the compounder all the information he desires in the matter of organic acids as related to litharge curing. Various questions of practical importance arise. I n the present paper an attempt will be made not comprehensively or systematically to survey all these numerous questions, but only to illus...

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“…According to the systems usually in vogue the water is treated very much after the fashion of the Oberlin plant so far as the addition of the chemicals is concerned. But the usual method, and the one used in Oberlin for several years, is to leave the treated water in a settling basin for about 18 hours and then run it directly onto the sand filters. This method, however, caused considerable trouble.…”

Section: After-precipitationmentioning

confidence: 99%

“…This suggested that there might be present in the acetone extract a very minute amount of a 1' British Patent 260,001 (1926). 18 J. Chem. Soc.…”

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confidence: 99%

Water-Softening as Practiced at Oberlin, Ohio

Chapin¹

1927

Ind. Eng. Chem.

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Table II shows the toxic concentration of pyridine and quinoline when added to western yellow pine sawdust to be 2.45 and 1.08 per cent, respectively.It is evident that pyridine is much less toxic to Fomes annosus than quinoline. Owing to the low boiling point of pyridine, its high volatility, and low toxicity, it is obvious that this particular substance can play no important part in influencing the preservative properties of shale oil. Quinoline, on the other hand, owing to its high boiling point, low degree of volatility, and high toxicity, will undoubtedly influence the toxicity of shale oil to a high degree.

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Reactions of Accelerators during Vulcanization - VI. Organic Acids and Inorganic Accelorators

Abstract: leather of pH = 9 gained 13.8 per cent in weight even though it lost some tannin, showing a very pronounced oxidation of the alcohol followed by aldehyde tannage.

Cited by 5 publications

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Dispersion of Pigments in Rubber¹: I—Microscopical Studies of Agglomeration and Flocculation

Dispersion of Pigments in Rubber¹: I—Microscopical Studies of Agglomeration and Flocculation

Stearic Acid in Litharge-Cured Rubber Compounds

Water-Softening as Practiced at Oberlin, Ohio

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Reactions of Accelerators during Vulcanization - VI. Organic Acids and Inorganic Accelorators

Abstract: leather of pH = 9 gained 13.8 per cent in weight even though it lost some tannin, showing a very pronounced oxidation of the alcohol followed by aldehyde tannage.

Cited by 5 publications

References 0 publications

Dispersion of Pigments in Rubber1: I—Microscopical Studies of Agglomeration and Flocculation

Dispersion of Pigments in Rubber1: I—Microscopical Studies of Agglomeration and Flocculation

Stearic Acid in Litharge-Cured Rubber Compounds

Water-Softening as Practiced at Oberlin, Ohio

Contact Info

Product

Resources

About

Dispersion of Pigments in Rubber¹: I—Microscopical Studies of Agglomeration and Flocculation

Dispersion of Pigments in Rubber¹: I—Microscopical Studies of Agglomeration and Flocculation