Structural Features of Buna S

Kemp, A. R.; Straitiff, W. G.

doi:10.1021/ie50416a009

Cited by 8 publications

(13 citation statements)

References 4 publications

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“…Very few papers have endeavored to evaluate the sulphur diffusion in rubbers prior to the elaboration of radiotracer-methods ( 5 ) . Auerbach and Gehman ( 6 ) succeeded in applying the radioisotope SS5 and in measuring the diffusion coefficient for natural rubber at 40 and 60°C.…”

Section: Diffusion In Rubbermentioning

confidence: 99%

Radiotracer measurements of sulphur diffusion in rubbers

Mozisek¹

1970

Polymer Engineering & Sci

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The object of measurement was the diffusion of elemental sulphur labelled with the radioisotope S35 in typical representatives for various types of rubber. The highest values of diffusion coefficient have been found in cis 1,4 polybutadiene. The lowest measured value was found for butyl rubber. The activation energy, expressing the temperature dependence of the diffusion coefficients, ranges from 4 to 10 kcal mol−1. For some rubbers studied, the activation energy is to a certain degree dependent upon temperature. The values of the diffusion coefficients and the characteristic constants for their temperature dependence are related to the mobility of the macromolecular segments.

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Section: Diffusion In Rubbermentioning

confidence: 99%

Radiotracer measurements of sulphur diffusion in rubbers

Mozisek¹

1970

Polymer Engineering & Sci

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“…1. It is possible for polymerization to occur in the 1,2 as well as in the 1,4 position; branched chains and "pendant" vinyl roups result, which would be expected to affect chemical heavier as well as physical characteristics (1,18). Another contributing fact is the probability that both cis and trans structures exist in the same synthetic polymer.…”

mentioning

confidence: 99%

“…This, together with the presence of branched chains produced by 1,2 polymerization, leads to a high degree of nonsymmetry in the polymer; it probably accounts for the fact that this polymer, unlike natural rubber, does not crystallize on stretching and the probably related fact that pure gum stocks have relatively poor strength. Kemp and Straitiff (18) believe that this lack of structural symmetry may be responsible for inability to cross link and form a desirable structure in the vulcanízate.…”

mentioning

confidence: 99%

mentioning

confidence: 99%

“…The molecular weight is, in general, lower than that of natural rubber (19), and its distribution is quite broad (18). It has been indicated (18) that the presence of the lowest molecular weight polymers is detrimental to the quality of the vulcanizates. Highmolecular-weight fractions, which compare favorably with natural rubber on the basis of molecular weight, tensile, and modulus, are tough and hard to handle on a mill.…”

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confidence: 99%

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Structural Changes in Vulcanization of Buna.

Keck¹,

Cheyney²

1945

Ind. Eng. Chem.

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On the mechanism of ozone degradation of SBR

Delman¹,

Simms²,

Ruff³

1960

J. Polym. Sci.

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The reaction mechanism of the ozone attack of SBR copolymers was studied to obtain information for use in the development of elastomeric materials having improved resistance to deterioration in service. Techniques of ultracentrifugation and viscometry were utilized to follow molecular changes induced by ozone. Chemical changes were investigated by measuring variations in active oxygen group concentration. Results suggest that the autocatalytic degradation of uninhibited SBR was initiated by a random ozone attack at a double bond on the unozonized chain, producing an ozonide which decomposed spontaneously, forming small segments with activated chain‐ends. This primary reaction, in the presence of oxygen, activated an α‐methylenic chain cleavage process which was terminated when the molecules were degraded to a limiting size, where no more R. radicals were formed from α‐methylenic groups. The reaction was also terminated when oxygen was removed from the system.

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Structural Features of Buna S

Cited by 8 publications

References 4 publications

Radiotracer measurements of sulphur diffusion in rubbers

Radiotracer measurements of sulphur diffusion in rubbers

Structural Changes in Vulcanization of Buna.

On the mechanism of ozone degradation of SBR

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