Styrene block copolymers
Elastomers TPE > Blocks
Styrene block copolymers (SBC) | ||||||||
The styrene block copolymers (SBC), which combine the properties of a thermoplastic resin and those of an elastomer, are based on block copolymers having an elastomeric center segment and end segments of polystyrene. There are many possible block configurations of SBC styrene block copolymers. The common vernacular industry includes diblock materials (polystyrene-elastomer), polystyrene-elastomer center-segment-polystyrene linear structures, as well as a variety of branched configurations. SBS - Poly (styrene-butadiene-styrene) SIS - Poly (styrene-isoprene-styrene) SEBS - Poly (styrene-ethylene / buty-butylene) SEPS - and Poly (styrene-ethylene / propylene-styrene) This report follows the industry convention and includes diblock, linear and multi-block styrenic block copolymers that can be classified as thermoplastic elastomers. Of these different types of SBC, linear materials are still the most common. | ||||||||
Symbols | Formula | |||||||
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Types | ||||||||
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The structure of SBC makes an unusual combination of properties | ||||||||
The polystyrene end segments form separate regions or domains of the elastomeric center segments. At room temperature, the polystyrene segments act as physical bonds to tie the elastomeric segments. in a network similar to that of conventional vulcanized rubber. At higher temperatures, the end segments soften and the material can flow under tension. Styrenic block copolymers are an important family of materials in the thermoplastic elastomer (TPE) category. These materials have many of the properties of vulcanized rubbers, but they can be molded and extruded in conventional thermoplastic processing equipment. This gives them productivity advantages compared to vulcanized rubbers, which are thermostable and are processed by slow and costly curing processes. | ||||||||
Unsaturated and saturated | ||||||||
Los SBC insaturados (SBS y SIS) son suaves y flexibles con excelentes propiedades de adherencia y adhesivo. Por lo tanto, tienden a encontrar uso en adhesivos (especialmente SIS), selladores y aplicaciones de modificación de betún; mientras en el calzado se usa SBS sobre la base de su suavidad y bajo coste. Los materiales hidrogenados, SEBS, y SEPS, han mejorado la resistencia a la intemperie y la resistencia a los rayos UV, y por lo tanto, encuentran uso en compuestos para productos duraderos, aunque a veces también se usan en formulaciones adhesivas. Tanto los materiales insaturados como los saturados encuentran uso como modificadores de polímeros o capas de unión dependiendo del producto final requisitos. | ||||||||
Process | ||||||||
The regular production process for SBS, SIS and subsequently SEBS or SEPS by hydrogenation. The technology is very flexible and allows plants to produce not only SBS, SIS and SEBS / SEPS, but also, in some cases, SB Rubbers of the more conventional type. The plants are usually multi-flow can produce several degrees in parallel. This reflects the fragmented and differentiated nature of the product and its markets. The operation is an interesting balance between discontinuous (copolymerization) and continuous processes (recovery of polymers and solvents). The SBS and SIS polymers can be prepared by four different processes, each with a unique technology features: Difunctional initiating process Sequential addition process of three stages. Coupling process Tapered block process The linear block copolymers A-B-A can be produced by the use of difunctional initiators (for example, sodium naphthalene of dilithium compounds). | ||||||||