SBS thermoplastic elastomer

Closely related to these but thermoplastic rather than rubber-like in character are the K-resins developed hy Phillips. These resins comprise star-shaped butadiene-styrene block copolymers containing about 75% styrene and, like SBS thermoplastic elastomers, are produced by sequential anionic polymerisation (see Chapter 2). 

Polymers with blocks containing different tactcities can be produced, e.g., atactic PP (amorphous)/isotactic PP (semi-crystalline) can be made using metallocene catalysts. They behave in a manner similar to SBS thermoplastic elastomers. 

Thermoplastic elastomers are materials which exhibit elastomeric behaviour at room temperature, but which can be processed as thermoplastics. Before one can understand the performance of these materials an understanding of how they can give their unique properties of elasticity and thermoplasticity is required this is best done by considering the styrene-butadiene-styrene (SBS) thermoplastic elastomers. 

Stabilization of Styrene-Butadiene-Styrene (SBS) Thermoplastic Elastomers (Styrene Butadiene Styrene Block Copolymer)... 

Figure 3.11 Three-dimensional SBS thermoplastic elastomer network. (From Vonk W.C. and G. Van Gooswilligen, Improvement of paving grade bitumens with SBS polymers. Proceedings of the 4th Eurobitume, Vol. I, p. 299. Madrid, 1989.)...

Elexar Triblock SEES or SBS thermoplastic elastomers Shell Chem. 

Over 60% of butadiene output is used by the rubber industry. About 30% of the butadiene is used in SBR production, 25% in BR production, 4% in CR production, and 2% in NBR production. Some butadiene goes into producing SBS thermoplastic elastomers. 

Anionic polymerization requires a type of monomer that contains an electron-withdrawing substituent such as phenyl, carboxyl, nitrile, and diene. Successful industrial examples are some styrenic products such as styrene-butadiene mbber (SBR) and styrene-butadiene-styrene (SBS) thermoplastic elastomer resins. Commonly used industrial catalysts are ethyl lithium (C2H5li) and sodium naphthalide (CioHgNa), which quickly dissolves and dissociates in a proper solvent. The primary anion R" reacts with monomer and initiates chain growth through successive propagation steps ... 

SBS thermoplastic elastomers are used as pressure-sensitive adhesives and in all fields of application of elastomers with processing techniques usually intended for thermoplastics. 

Modified Bitumen Membranes. These membranes were developed in Europe during the late 1950s and have been used in the United States since the late 1970s. There are two basic types of modified asphalts and two types of reinforcement used in the membranes. The two polymeric modifiers used are atactic polypropylene (APP) and styrene—butadiene—styrene (SBS). APP is a thermoplastic polymer, whereas SBS is an elastomer (see Elastomers, thermoplastic elastomers). These modified asphalts have very different physical properties that affect the reinforcements used. 

With these polymers hard blocks with T s well above normal ambient temperature are separated by soft bloeks which in the mass are rubbery in nature. This is very reminiscent of the SBS triblock elastomers discussed in Chapter 11 and even more closely related to the polyether-ester thermoplastic elastomers of the Hytrel type deseribed in Chapter 25. 

SBS (linear or star) Polystyrene Polybutadiene Polystyrene Polyethylene Thermoplastic elastomer... 

Currently, important TPE s include blends of semicrystalline thermoplastic polyolefins such as propylene copolymers, with ethylene-propylene terepolymer elastomer. Block copolymers of styrene with other monomers such as butadiene, isoprene, and ethylene or ethylene/propy-lene are the most widely used TPE s. Styrene-butadiene-styrene (SBS) accounted for 70% of global styrene block copolymers (SBC). Currently, global capacity of SBC is approximately 1.1 million tons. Polyurethane thermoplastic elastomers are relatively more expensive then other TPE s. However, they are noted for their flexibility, strength, toughness, and abrasion and chemical resistance. Blends of polyvinyl chloride with elastomers such as butyl are widely used in Japan. ... 

Thermoplastic elastomers (TPEs) are either block copolymers (SBS, SEES, SEPS, TPU, COPA, COPE) or blends, such as TPO (elastomer/hard thermoplastic, also referred to as thermoplastic olefin) and TPV (fhermoplastic vul-canizafe, blend of a vulcanized elastomer and a hard fhermoplastic). These types represent the majority of fhe TPEs other types are either specialty or small-volume materials. 

The hydrogenation of the centre block of SBS copolymer produced oxidation stable thermoplastic elastomer. This product was commercialized by the Shell Development Company under the trade name of Kraton G. The field of thermoplastic elastomers based on styrene, 1-3-butadiene or isoprene has expanded so much in the last 10 years that the synthetic rubber chemist produced more of these polymers than the market could handle. However, the anionically prepared thermoplastic system is still the leader in this field, since it produced the best TPR s with the best physical properties. These TPR s can accommodate more filler, which reduces the cost. For example, the SBS Kraton type copolymer varies the monomer of the middle block to produce polyisoprene at various combinations, then, followed... 

Thermoplastic elastomers (TPE s) are characterized by the exceptional property that, without vulcanization, they behave as cross-linked rubbers. They are block-copolymers, in which blocks of the same nature assemble in hard domains, acting as cross-links between the rubbery parts of the chain. These hard domains lose their function when they reach their softening temperature, so that the material can then be processed as a thermoplast. One of the oldest member of the family of TPE s is SBS (styrene-butadiene-styrene block copolymer), but several other TPE s have been developed, i.a. on the basis of polyesters, polyurethanes and polyolefins. In their properties these polymers cover a broad range between conventional rubbers and soft thermoplastics. 

The above thermal analysis studies demonstrated the enhanced thermal stability of POSS materials, and suggested that there is potential to improve the flammability properties of polymers when compounded with these macromers. In a typical example of their application as flame retardants, a U.S. patent39 described the use of preceramic materials, namely, polycarbosilanes (PCS), polysilanes (PS), polysilsesquioxane (PSS) resins, and POSS (structures are shown in Figure 8.6) to improve the flammability properties of thermoplastic polymers such as, polypropylene and thermoplastic elastomers such as Kraton (polystyrene-polybutadiene-polystyrene, SBS) and Pebax (polyether block-polyamide copolymer). 

Styrene-Diene. These ( styrenic ) thermoplastic elastomers are block copolymers of styrene with butadiene (SBS) or isoprene (SIS) in about 30/70 monomer ratio. 

Triblock copolymers have a central B block joined by A blocks at the end. A commercially important ABA-triblock copolymer is polystyrene-bloc/j-polybutadiene-bZoc/z-polystyrne (SBS) a thermoplastic elastomer. 

Thermoplastic elastomers (TPE) Styrene-butadiene-styrene (SBS) and styrene-isoprene-styrene (SIS) block copolymers represent primary materials for other hotmelt adhesives. They are characterized by long open times, high elasticity levels, good spring qualities and a lasting stickiness, so that precoated surfaces always retain some of the qualities of PSAs. The melting temperatures of these adhesives are particularly low at about 65°C, so that they can be used for thermally sensitive materials (foams, fleeces, thin films). 

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