Styrene block polymer

Fig. 4. MiceUular gelation mechanism. A shows micelle nuclei, highly cross-linked B, boundary where micelle growth terminates in styrene block polymers.

Radial styrenic block polymers, PholUps (Solprene)... 

Several attempts have been made to superimpose creep and stress-relaxation data obtained at different temperatures on styrcne-butadiene-styrene block polymers. Shen and Kaelble (258) found that Williams-Landel-Ferry (WLF) (27) shift factors held around each of the glass transition temperatures of the polystyrene and the poly butadiene, but at intermediate temperatures a different type of shift factor had to be used to make a master curve. However, on very similar block polymers, Lim et ai. (25 )) found that a WLF shift factor held only below 15°C in the region between the glass transitions, and at higher temperatures an Arrhenius type of shift factor held. The reason for this difference in the shift factors is not known. Master curves have been made from creep and stress-relaxation data on partially miscible graft polymers of poly(ethyl acrylate) and poly(mcthyl methacrylate) (260). WLF shift factors held approximately, but the master curves covered 20 to 25 decades of time rather than the 10 to 15 decades for normal one-phase polymers. 

Blends of butadiene-styrene block polymers with polyolefins, particularly polypropylene are mentioned in literature to improve the impact strength of the latter. Since similar improvements can be realized from the use of polyolefin block polymers, the blends have not gained much recognition. However, butadiene-styrene radial teleblock polymers are blended into polyethylene film, to increase the tear resistance and tensile impact. ... 

A relatively new development which promises to gain in importance in the future is the modification of asphalt by butadiene-styrene block polymers.44 The block polymers help reduce the low temperature brittleness and impart resistance to flow at elevated temperatures. Applications in mastics, automobile body undercoatings and waterproofing materials such as high quality roofing membranes are envisaged. 

Fig. 4. Micellular gelation mechanism. A shows micelle nuclei, highly cross-linked B, boundary where micelle growth terminates in styrene block polymers. Styryl free radicals simultaneously initiate micelle nuclei at points of high fumarate concentration. The micelles continue to expand, interacting with free styrene until the fumarate groups are depleted. The micelles eventually overlap at the boundaries that contain higher levels of terminal styrene...

The first workable capping agents for controlled radical polymerization were discovered by Rizzardo et al. [77, 78] who used nitroxides. The nitroxide reacts reversibly with radical chain ends but itself does not initiate the monomer. They called their new system Stable Free Radical Polymerization (SFRP). Scheme 32a depicts an example of SFRP using TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxy). SFRP was developed independently by Georges at Xerox for the synthesis of styrene block polymer as dispersing agents [79]. 

Super High Impact Polystyrene Based on Polystyrene and Butadiene-Styrene Block Polymer Blends... 

Gaseous CSI treated styrene - isoprene-styrene block polymer. 

Synonyms Styrene block polymer with 1,3-butadiene, hydrogenated... 

Stereon, Styrenic block polymers. Firestone Synthetic Rubber Latex Co. 

Hot-melts generally are based on one or more thermoplastic resins. The largest portion of commercial hot-melt adhesives has for many years been based on ethylene-vinyl acetate copolymers having a vinyl acetate content of about 20-40%. The styrenic block polymers which are thermoplastic elastomers also make up a large portion of hot-melts. Other resins that have been foimd useful as bases... 

The use of styrenic block polymers to provide a critical level of cohesive strength or integrity for melt forming operations. The specific uses involve the "green processing of tire rubbers and the thermoforming of crystalline thermoplastics. 

Triblock polymers and radial block polymers of styrene and butadiene (or isoprene) are successful commercial thermoplastic elastomers pioneered by the Shell Chemical Company and the Phillips Petroleum Company. The low diene and high styrene block polymers are clear impact resisting plastics marketed by the Phillips Petroleum Company under the trade name K-Resins. One common deficiency of these polymers is the relatively low glass temperature (Tg) of the polystyrene end blocks. For the thermoplastic elastomers the service temperatures are limited to below 65°C. The Vicat softening... 

About 99% of all ethylbenzene produced is converted to styrene, which is used to make SBR for the rubber industry as well as polystyrene and ABS for the plastics industries. Also, styrene is used to make SBVP latex (for use in RFL adhesive dips) as well as to produce styrenic block polymers, such as SIS, SBS, SEES, and SEPS, which are used as thermoplastic elastomers. 

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