Elastomers butadiene

Butadiene—Methacrylic Acid Ionomers. Carboxyl groups can readily be introduced into butadiene elastomers by copolymerization, and the effects of partial neutralization have been reported (63—66). The ionized polymers exhibit some degree of fluidity at elevated temperatures, but are not thermoplastic elastomers, and are very deficient in key elastomer properties such as compression set resistance. 

Sodium is a catalyst for many polymerizations the two most familiar are the polymerization of 1,2-butadiene (the Buna process) and the copolymerization of styrene—butadiene mixtures (the modified GRS process). The alfin catalysts, made from sodium, give extremely rapid or unusual polymerizations of some dienes and of styrene (qv) (133—137) (see Butadiene Elastomers, synthetic Styrene plastics). 

Styrene—butadiene elastomers, emulsion and solution types combined, are reported to be the largest-volume synthetic mbber, with 28.7% of the world consumption of all synthetic mbber in 1994 (38). This percentage has decreased steadily since 1973 when SBR s market share was 57% (39). The decline has been attributed to the switch to radial tires (longer milage) and the growth of other synthetic polymers, such as polyethylene, polypropylene, polyester, and polystyrene. Since 1985, production of SBR has been flat (Table 3). 

FIGURE 16.12 Mooney viscosity at 175°C of butadiene elastomer mill mixed with 50 phr of N-234 10 phr of naphthenic oil with the labeled loading of a commercial peptizer (diphenyl dibenzamido-disulfide). 

Previous studies have demonstrated that QDI improves the formation of bound rubber. From the previous discussion of free-radical chemistry, the formation of bound mbber in butadiene elastomer compounds would be expected to occur at a higher rate than in NR. 

James, H. L., Gaylor, V. F., Anthony, N. R., "The Use of Liquid Exclusion Chromatography for Rapid Measurement of Gel in Styrene-Butadiene Elastomers," presented at the 1975 Gel Permeation Chromatography Seminar, Pittsburg, Pennsylvania (October, 1975). 

Polymers with solubility parameters differing from those of the solvent by at least 2.0 H, will not dissolve in the solvent at room temperature. Thus although unvulcanized natural rubber (NR), unvulcanized styrene-butadiene elastomer (SBR), unvulcanized butyl rubber, and EPDM dissolve in gasoline or benzene, the vulcanized (cross-linked) polymers are swollen but will not dissolve due to the presence of the crosslinks. 

Landel and Fedors (53, 54) have recently explored the usefulness of extreme value statistics applied to the statistical distribution of rupture in various unfilled polymer specimens. Both breaking stress and breaking strain of natural rubber (47) and styrene butadiene elastomers (53, 54) may be described by the double exponential distribution... 

The network of the Styrene-Butadiene Elastomers is based on a second principle which, again, differs from the covalent cross-links of typical theromsets. The three-dimensional structure in this case is... 

The Polyurethanes, the third group of polymers which will be discussed in this paper, represent a much broader scope than either the ionomers or the styrene- butadiene elastomers. Because of the large number of possible monomers which can be used for the preparation of polyurethanes and their respective combinations, the... 

IonomerM Polyurethane[Pg.44]

Shell Chemical Company, Styrene—butadiene-Elastomers Technical Bul-... 

Physically, vegetable oils and their methyl and ethyl esters are very similar to diesel fuel. There has been no indication that any of the metals currently used in the distribution, storage, dispensing, or onboard fuel systems for diesel fuel would not be compatible with vegetable oil fuels. However, there are reports of some signs of incompatibilities with fuel transfer hoses [3.15], and nitrile and butadiene elastomers [3.16] with methyl esters. Elastomers with high fluorine... 

Acrylonitrile-Butadiene Elastomers. These polymers, the so-called nitrile rubbers , are used dissolved in ketone or other highly polar solvents. When they are compounded with thermosetting phenolic resins it is possible to obtain good resistance to elevated temperatures. 

TABLE 2. Physical properties of styrene-butadiene elastomers initiated with selected thioacetals and terminated with vulcanization agents. 

Modification of macromolecular material properties by hydrogen bond formation has been demonstrated at the example of thermoreversible networks Stadler modified poly(butadiene) elastomers with urazole groups to introduce hydrogen-bonded cross-links into the system. In fact, thermoreversible cross-linking appeared due to the urazol-urazole molecular recognition, causing intermolecular cross-links [408,467]. The group of Meijer expanded the approach by the synthesis of two... 

Prior to 1941, Germany had a major technical and industrial lead over the USA, having already established an industrial styrene monomer production process, a styrene-butadiene elastomer process and a mass styrene polymerization process [6]. Figure 1.2 shows the polymerization vessels at I. G. Farben in 1940. Figure 1.3 shows a bank of polymerization kettles. The Germans began the first technical production of polystyrene in 1930 while the first production of polystyrene in the USA was some 8 years later by Dow in 1938. 

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