Styrene-butadiene rubbers sequences

Order-disorder transitions and spinodals were computed for linear multi block copolymers with differing sequence distributions by Fredrickson et al. (1992). This type of copolymer includes polyurethanes, styrene-butadiene rubber, high impact polystyrene (HIPS) and acrylonitrile-butadiene-styrene (ABS) block copolymers. Thus the theory is applicable to a broad range of industrial thermoplastic elastomers and polyurethanes. The parameter... 

Synthetic rubbers now constitute about two thirds of the rubber that is used worldwide. The major synthetic rubber, called styrene-butadiene rubber, or SBR, is a copolymer formed by radical polymerization of a mixture of 25% styrene and 75% 1,3-butadiene. The monomers add in a random sequence. The incorporation of each... 

Both addition and condensation polymerization can be carried out with mixtures of two or more types of monomers present in the reaction mixture. The result is a random copolymer that incorporates both types of monomers in an irregular sequence along the chain. For example, a 1 6 molar ratio of styrene to butadiene monomers is used to make styrene-butadiene rubber (SBR) for automobile tires, and a 2 1 ratio gives a copolymer that is an ingredient in latex paints. 

Example 5 (Batch pipeline sequencing). Suppose a one-to-one serial pipeline that connects two chemical sites. The provider site prodtices the raw and intermediate materials for the consumer site. Suppose that the consumer site produces Styrene-based chemicals such as Polystyrene and Styrene-Butadiene rubber. Raw materials for Styrene production are Benzene and Ethylene. Among others, a steam cracker provides Ethylene and Pygas, which is subsequently refined to Benzene. It is assumed that the capacities of these plants are unbalanced such that the deficit of Pygas and Benzene has to be imported. Additionally, the cracker feed, Naphtha, has to be imported. 

Characterization of Styrene Sequence Distribution in Solution Styrene-Butadiene Rubbers by Anionic Polymerization... 

The broad range of control of solution polymer structure and macrostructure of styrene-butadiene rubbers that is only possible using lithium catalysts was discussed in Section 2. We have seen how the microstructure of the butadiene units in the chain and comonomer sequence distribution can be controlled with the addition of polar modifiers and/or variations in pol5onerization process variables. Additionally, the unique control of macrostructure features and the new possibilities offered by reactive functional groups were discussed as part of the molecular engineering capabilities of solution anionic polymerizations. 

ABS Three-component copolymer of acrylonitrile, butadiene, and styrene, alloy Rubber-toughened materials in which the matrix can be a mixture of polymer tyrpes. alternation copolymer Ordered copolymer in which every other building is a different mer. azeotropic copolymer Copolymer in which the feet and composition of the copolymer are the same, blends Mixtures of different polymers on a molecular level may exist in one or two phases, block copolymer Copolymer that contains long sequences or runs of one mer or both mers. 

When simple crosslinked elastomers are stretched and held at. high elongation, two consecutive phenomena occur (1) a smooth relaxation period, and (2) sudden failure. This sequence is depicted in Figure 1.22 for poly-(styrene-co-butadiene) rubber (Rodriguez, 1970, Chapter 9 Scott, 1967 Smith, 1964 Smith and Stedry, 1960). 

Early results with cryomicrotomes were described by Cobbold and Mendelson [80]. Polyurethane elastomer, a blend of crystalline and noncrystalline polymers, showed spherulitic textures after sectioning at about -70°C. Injection molded polypropylene (PP) was also sectioned at about -70°C, while polytetrafluoroethylene (PTFE) was sectioned at much lower temperatures. The authors concluded that the technique, though difficult, had potential. Extruded styrene-butadiene-styrene (SBS) copolymer was prepared by cryosectioning with a diamond knife in liquid air at —85 to —115°C, followed by osmium tetroxide vapor staining for one hour [81]. This method revealed the alternating sequence of the polystyrene and polybutadiene lamellae. Odell et al. [82] prepared extruded triblock copolymer by first chemically hardening the polybutadiene, with osmium tetroxide, followed by cryoultramicrotomy to produce 30 nm thick sections which showed fine structure details. Parallel polystyrene rods were observed in the SBS copolymer. Ultramicrotomy and selective staining with osmium tetroxide was also used in the preparation of a binary blend of PP and thermoplastic rubber [83]. 

Other commercial copolymers which are typically random are those of vinyl chloride and vinyl acetate (Vinylite), isobutylene and isoprene (butyl rubber), styrene and butadiene (SBR), and acrylonitrile and butadiene (NBR). The accepted nomenclature is illustrated by EP, which is designated poly-ethylene-co-propylene the co designating that the polymer is a copolymer. When the copolymers are arranged in a regular sequence in the chains, i.e., ABAB, the copolymer is called an alternating copolymer. A copolymer consisting of styrene and maleic anhydride (SMA) is a typical alternating copolymer. 

Government Rubber Styrene. General-purpose synthetic rubbers that were originally produced in government owned plants as GR-S. They are copolymers obtained by the polymerization of butadiene and styrene in a ratio of approx 3 1. The chains contain a random sequence of the two monomers. Very similar in composition to Buna S, bra ton, Sol-p re pie, Stereon. Review P. Schneider el at., in Ullmann,... 

When the sequences making up the segments are random copolymers, the prefix CO may be introduced, with the major component monomer preceding the minor constituent. A backbone polymer of butadiene-styrene rubber grafted with styrene containing a small percentage of acrylic acid would be described as poly[(butadiene-co-styrene)-(styrene-co-acrylic acid)] and could be schematically represented as... 

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