Styrene elastomers

Thermoplastic elastomers are often multiphase compositions in which the phases are intimately dispersed. In many cases, the phases are chemically bonded by block or graft copolymerization. In others, a fine dispersion is apparentiy sufficient. In these multiphase systems, at least one phase consists of a material that is hard at room temperature but becomes fluid upon heating. Another phase consists of a softer material that is mbberlike at RT. A simple stmcture is an A—B—A block copolymer, where A is a hard phase and B an elastomer, eg, poly(styrene- -elastomer- -styrene). 

The macroradicals of natural rubber react with those of the styrene elastomer, due to the presence of the very reactive 1,2 pendent vinyl groups in the latter. This mechanism leads to a structure where the styrene rubber forms a gel network with grafted branches of natural rubber. 

Typical mechanical properties for transparent injection-molded polymers, designated MBAS, having a compositional range of from 11-18%, 1,3-butadiene, 34-39% styrene, and 23-25% each of acrylonitrile and methyl methacrylate are given in Table IV. This polymer is closely akin to the polyblend described previously, differing by containing a butadiene-styrene elastomer backbone, with a terpolymer resin graft consist-... 

The development of highly reinforcing furnace blacks paralleled the creation of the synthetic-rubber industry. Improved cold butadiene-styrene elastomers reinforced with these new blacks give vulcanizates that are superior to natural rubb m tire treads. 

Commercially, the poly(styrene- -elastomer- -styrene) materials are made by anionic polymerization (7,45—47). An alkj thium initiator (RLi) first reacts with styrene [100-42-5] monomer ... 

Butadiene is a petroleum product obtained by catalytic cracking of naphtha or light oil or by dehydrogenation of butene or butane. It is used to produce butadiene-styrene elastomer (for tires), synthetic rubber, thermoplastic elastomers, food wrapping materials, and in the manufacture of adiponitrile. It is also used for the synthesis of organics by Diels-Alder condensation. 

Dow Plastics Dow materials selection guide includes ISO and ASTM database modules for engineering plastics, styrenics, elastomers, and polyolefins, http // www.dow.com/plastics... 

CAS 6683-19-8 EINECS/ELINCS 229-722-6 Uses Antioxidant for polyolefins, styrenics, elastomers, adhesives, lubricants, oils, PP, LDPE, LLDPE, HOPE, HIPS, ABS, polyestet EVA, cellu-losics, nylon, polyester, PS, PVC, acetal, EPDM, PU food-contact pressure-sensitive adhesives, coatings, paper, wood preservatives antioxidant for food-grade polymers... 

In some cases, lack of noticeable influence of electron beam radiation on the values of tensile and Charpy impact strengths of 24-23-21-15-17 LDPE-HDPE-PP-PS-PET blends (based on recycled polymers) compatibilized with 1% trimethylol propane trimethylacrylate (TMPTMA) were found. Zenkiewicz et al. ° explained this lack of influence by the protective action of aromatic rings of PS and PET that hindered cross-linking. In the same article, the addition of 10% of styrene-ethylene/butylene-styrene elastomer grafted with maleic anhydride (SEBS-g-MA) led to the great increase of both tensile and Charpy impact strengths. 

Finaprene, solution polymerized butadiene, butadiene/styrene elastomers, as random and deblock copolymers, are available from Fina Chemicals [83]. 

Historically, a number of different impact-modification technologies have been used. These include various maleated oleflnic rubber such as EB, EP, and so on SBS bromi-nated isobutylene-para-methyl styrene elastomers produced by Exxon and many others. Dow s metallocene-based ethylene-a-olefln elastomers were found to be very effective as well. The rheology of toughened nylon 6,6 is usually directly related to the maleic anhydride graft level of the impact modifier. Rubber particle size averages of greater than 0.25 pm and less than 0.5 pm are required to achieve the required balance of mechanical performance. Optimum particle size varies with the percentage of rubber. 

Electrosol, Antistatic agents, Alframine Corp. Elexar, Styrenic elastomers, wire and cable, Teknor Apex International Elfan, PVC emulsifier, Akzo Nobel Chemicals Inc. 

The systems based on poly(butadiene-co-styrene) elastomer and... 

SEBS Styrene-ethylene-butadiene-styrene elastomer ... 

Commodity resins. Outside the range of phase co-continuity the PO/PS blends need to be compatibilized. There are several methods of compatibilization out of which the addition of styrene-elastomer block copolymers and reactive radical co-grafting are most conunon. For example, PCW comprising 55-75 wt% PO, 5-25 wt% PS, 5-15 wt% PVC, and 0-10 wt% of other thermoplastics, was compatibilized with 3-20 wt% SB, and stabilized by adding 0.1 -0.5 wt% of pentaerythritol ester and tris(2,4-di-tert-butyl phenyl) phosphite at a ratio of 5 1 to 1 5. The recycled mixtures showed good long-term performance [8]. 

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