Kraton

KRATON Thermoplastic Elastomers bulletins. Shell Chemical Co., Houston, Tex. 

Thermoplastic Elastomers. These represent a whole class of synthetic elastomers, developed siace the 1960s, that ate permanently and reversibly thermoplastic, but behave as cross-linked networks at ambient temperature. One of the first was the triblock copolymer of the polystyrene—polybutadiene—polystyrene type (SheU s Kraton) prepared by anionic polymerization with organoHthium initiator. The stmcture and morphology is shown schematically in Figure 3. The incompatibiHty of the polystyrene and polybutadiene blocks leads to a dispersion of the spherical polystyrene domains (ca 20—30 nm) in the mbbery matrix of polybutadiene. Since each polybutadiene chain is anchored at both ends to a polystyrene domain, a network results. However, at elevated temperatures where the polystyrene softens, the elastomer can be molded like any thermoplastic, yet behaves much like a vulcanized mbber on cooling (see Elastomers, synthetic-thermoplastic elastomers). 

Kraton D and Cariflex Shell General-purpose, soluble linear and branched B oil also compounded products... 

Hydrogenated SBS triblock polymers have become increasingly important (Kraton G by Shell). With the original polybutadiene block comprised of 65% 1,4-and 35% 1,2-structures the elastomeric central block is equivalent to that of a high-ethylene ethylene-butene rubber. 

The final radial polymer [58] recently introduced is Kraton D-KX222C, rep-... 

Kraton Polymers has developed a multiarm SIS (Kraton 1320X [37,46,47,50]) and SBS (Kraton KX-222C, [48,49]) for rapid UV/e-beam cure. Besides heat resistance improvements, plasticizer resistance is also improved in cured rubber-based systems. The dioctyl phthlate plasticizer common in PVC backing films is soluble in the styrenic domains of SBCs. Crosslinking of the mid-block provides cohesion even after plasticizer attack [51]. 

Fig. 20. UV initiated cationic cure of epoxidized block copolymer in the presence of alcohol (Kraton Polymer s EKP-207 and L1203 inono-ol).

An interesting observation arose with the thermoplastic elastomer styrene/ butadiene (S/B) tri-block copolymer (Kraton ). These are made by anionic... 

The pathway and kinetics of the C to S transition have been studied on shear-aligned cylinders of the commercial diblock copolymer of PS and poly(ethylene-co-butylene) (KRATON G 1657 Shell Chemical Company) [143, 144], A complete dissolution of the cylindrical structure before the epitaxial... 

Styrenic SBS/SIS (styrene-isoprene-styrene block copolymers) CariflexTR, Kraton... 

Styrene-ethylene-butylene-styrene block copolymer (SEBS) Kraton G, Elexar... 

DRESSING CHEST WOUND ONE WAY VALVE SELF ADHESIVE KRATON 10/PG 6510014081920 PG 74,67 ... 

It is another well-known problem that classical triblock TEP s, i.e. those of the Kraton-type, are often confined to applications under rather mild conditions, due to the relatively low Tg of the glassy phase, and/or the medium thermal stability of the rubbery phase In principle at least, good answers to that challenge can be offered by the type of synthesis discussed in this section. 

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