The Compounding of Hard GR-S

Morris, Ross E.; Mitton, Philip; Seegman, Irvin P.; Werkenthin, Theodore A.

doi:10.5254/1.3546687

Cited by 2 publications

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“…Plasticizers known to be efficient in lowering the brittle point of other elastomers and resins were used in most instances. II) were obtained from the manufacturer and literature (4,19) or determined experimentally.…”

Section: Methodsmentioning

confidence: 99%

Lactoprene EV Elastomer - Effects of Plasticizers

Mast¹,

Fisher²

1949

Ind. Eng. Chem.

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The films, after orientation, are anisotropic with regard to their mechanical properties. An oriented film has a higher modulus of elasticity along the axis of orientation than perpendicular to this axis. At an intermediate angle, the modulus has an intermediate value.It is, of course, well known that plasticized polyvinyl chloride becomes somewhat anisotropic in certain forming operations such as calendering, extrusion, etc. However, in such operations there is ordinarily an opportunity for a considerable amount of the orientation to relax before the structure is frozen in, so that only a residual effect is observed. Much larger variations in mechanical properties can be achieyed by temperature and stress sequences such as those used here. It is not unlikely that such recrystallization operations could find industrial application.A set of experiments was carried out to study the recrystailization under constant load in some detail. The plasticized films were first subjected to a stress at 30.0°C. After 60 minutes the samples were slowly heated to 90.0°C .; the heating cycle was 2 hours. On reaching 90.0°C ., the samples were cooled to 35.0°C. This cycle being completed, the samples were reheated to 90.0 °C. and the resulting contraction, due to melting of the crystalline structure, was followed. A typical diagram of the compliance (strain per unit stress) as a function of temperature, is presented in Figure 4. Here it is noted that process A, the initial upheat, is nonreversible. On cooling, curve B results. Process B, the cook ing process, on the other hand, is essentially reversible, since, on reheating, curve C results. There is some hysteresis during this process, but it is small. This curve is typical of the curves obtained with all the samples examined. If the load is removed at a low temperature-for example, 30°or 40°C .-only a small amount of recovery occurs.The samples retain their elongated, oriented form permanently, as far as-these experiments can show. (Samples stored for 6 weeks showed no signs of further recovery.) Of course, if the oriented samples are heated to a temperature of 90°C ., slow recovery to the original, unstressed length will take place, and the anisotropic properties will disappear. SUMMARY AND CONCLUSIONSPlasticized polyvinyl chloride and plasticized Vinylite VYNW exhibit a three-dimensional gel structure, the cross links of which are crystallites. The mechanical properties of a given formulation can be markedly altered by suitable recrystallization procedures.

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Section: Methodsmentioning

confidence: 99%

Lactoprene EV Elastomer - Effects of Plasticizers

Mast¹,

Fisher²

1949

Ind. Eng. Chem.

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“…GR-S compounding studies made by Morris, Mitt.on, Seegman, and Werkenthin (16) indicated that 50 parts of sulfur gave optimum physical results, and that by the proper choice of pigments, softeners, and accelerators, the time of cure could be shortened and ease of processing could be improved. It appeared difficult, however, to improve the physical properties beyond that of the base stock containing only GR-S and sulfur.…”

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Cellular Ebonites from Nitrile-Type Synthetic Rubbers

Clark¹,

Cheyney²

1949

Ind. Eng. Chem.

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Compounding studies are presented, showing the effect of several variables on the compression properties of cellular ebonites cured at 325°F ., including choice of nitrile-tvpe rubber, amounts of sulfur, diazoaminobenzene (blowing agent), and several selected plasticizers, pigments, and accelerators.Effects of some of these variables on the exothermic heat of vulcanization were also briefly studied . ACELLULAR ebonite is an expanded hard rubber, produced by combining the techniques for producing a hard rubber product with those for "blowing" a soft rubber or plastic sponge or foam. Cellular ebonite was made from natural rubber as early as 1931, when Beckmann (1) reported on the electrical properties of accumulator separator diaphragms made from "mieroporous" hard rubber. Little technical information has been published on the application of nitrile-type synthetic rubbers to the production of cellular ebonites, although such products have been used for radomes, flotation material, thermal insulation, and Sandwich-type structures.

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The Compounding of Hard GR-S

Cited by 2 publications

References 0 publications

Lactoprene EV Elastomer - Effects of Plasticizers

Lactoprene EV Elastomer - Effects of Plasticizers

Cellular Ebonites from Nitrile-Type Synthetic Rubbers

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