Styrenic block copolymer applications

Ranade, S.V., Richard, R.E., and Hehnus, M.N. Styrenic block copolymers for biomaterial and drug delivery applications, Acta Biomater., 1, 137, 2005. 

A product is only considered to be totally biodegradable if all its single components can be degraded naturally. Currently, pressure sensitive adhesives (PSA) are mostly based on non-biodegradable synthetic polymers such as polyacrylates, ethylene-vinyl acetate copolymers and styrene block copolymers [124]. Therefore there is a growing demand for the application of biodegradable PSAs on naturally degradable products like paper and cardboard. 

PVA in, 25 617 setting speed of, 25 579-580 smectites application, 6 697t solution, 1 532-534 structural, 1 534-545 styrenic block copolymers in, 24 714 use of latex in, 14 711-712 vinyl acetate polymers in, 25 578-583 viscosity of, 25 581 water-borne, 25 475 Adhesive systems, microencapsules in, 16 460... 

As more complex multicomponent blends are being developed for commercial applications, new approaches are needed for morphology characterization. Often, the use of Ru04 staining is effective, as it is sensitive to small variations in the chemical composition of the component polymers. For instance PS, PC, and styrene—ethylene/butylene—styrene block copolymers (SEBS) are readily stained, SAN is stained to a lesser degree, and PBT and nylons are not stained (158,225—228). 

Styrene block copolymers have been used as compatibilizers for mixed plastics to permit their processing for applications such as those outlined earlier (52,61). 

Styrenic Block Copolymers. The applications of these block copolymers are described in detail in Reference 6. 

Adhesives, Coatings, and Sealants. For these applications, styrenic block copolymers must be compounded with resins and oils (Table 10) to obtain the desired properties (56-58). Materials compatible with the elastomer segments soften the final product and give tack, whereas materials compatible with the polystyrene segments impart hardness. The latter are usually styrenic resins with relatively high softening points. Materials with low softening points are to be avoided, as are aromatic oils, since they plasticize the polystyrene domains and reduce the upper service temperature of the final products. 

Multiblock Copolymers. Replacement of conventional vulcanized mbber is the main application for the polar polyurethane, polyester, and polyamide block copolymers. Like styrenic block copolymers, they can be molded or extmded using equipment designed for processing thermoplastics. Melt temperatures during processing are between 175 and 225°C, and predrying is required scrap is reusable. They are mostly used as essentially pure materials, although some work on blends with various thermoplastics such as plasticized and unplasticized PVC and also ABS and polycarbonate (14,18,67—69) has been reported. Plasticizers intended for use with PVC have also been blended with polyester block copolymers (67). 

More recent examples include end-functionalized multiarmed poly (vinyl ether) (44), MVE/styrene block copolymers (45), and star-shaped polymers (46—48). With this remarkable control over polymer architecture, the growth of future commercial applications seems entirely likely. 

Although styrene-diene diblock copolymers are used in some applications, particularly in the area of viscosity index improvement (VII) additives for motor oil, styrenic block copolymers are most often used as thermoplastic elastomers. In these applications the styrene blocks phase separate, crosslinking the rubber blocks in a thermally reversible fashion. The simplest structure capable of exhibiting this behavior is a linear styrene-diene-styrene triblock. The most obvious way to produce such a molecule is by sequential polymeriza-... 

Albert Einstein said that it is good to make things as simple as possible, but not simpler. Beneath each simple statement about the properties of styrene block copolymers lie volumes of books, thousands of patents and countless pages of paper and electronic files dedicated to describing and understanding these highly useful polymers, and their applications. The task becomes reducing all of this to simple ideas, simple pictures and simple words, but not simpler . 

One simple idea is that styrenic block copolymers are almost never used as a stand-alone 100% neat polymer for any application or use. We tend to think about polymers in terms of this plastic soda bottle is polyester, or this carpet fiber is polyamide, or this house siding is PVC, or this garbage bag film is polyethylene , fully understanding and meaning that virtually 100% of the named object is that polymer. Our brains usefully process the named polymer properties set (as neat polymer) into the desired and required property set for its application. Life is simple in the 100% world. It is intuitive, and what we seem to know makes sense, looking either way properties wise, to why this polymer is used for this application. 

Having roughly defined the practical boundaries of commercial styrenic block copolymers with useful elastomeric properties, why do we have so many choices available within those boundaries What key property change will drive a polymer manufacturer and/or polymer user to head southwest in Figure 21.5 What would drive a customer to ask for something more northeasterly, please Or, go as far east as possible and do not worry about melt processability for my application . In essence, why is not everyone totally content to make, and use, polymer A for every application ... 

In these three treatments we have considered the very simple case of the molecules are only different in their midblock chemistry , and learned that molecular design is driven by how these molecules, as a minor component in an intended use, become reality with utility in the final application strongly in mind. The important neat properties that we design in, therefore, become those in the property set relevant to the intended usage. And also as important, the exact chemical nature of the rubber block itself becomes a key property in the world of usage and application of these styrenic block copolymers. 

Table 21.3 Primary applications of styrenic block copolymers and their 1997 global volumes [73] ...

Handlin DL Jr Trenor S, Wright K. Applications of thermoplastic elastomers based on styrenic block copolymers. In Matyjaszewski K, Gnanou Y, Leibler L, editors. Macro-molecular Engineering Precise Synthesis, Materials Properties, Applications. Volume 4. Weinheim, Germany Wiley-VCH 2007. p 2001. 

Handlin, D.L., Trenor, S., Wright, K., 2007. Applications of thermoplastic elastomers based on styrenic block copolymers. In Matyjaszewski, K., Gnanou, Y., Leibler, L. (Eds.), Macromolecular Engineering, vol. 4. Wiley, Weinheim, pp. 2001-2032. 

Resistance to hydrocarbon oils/solvents and maximum use temperature are key performance parameters for TPEs that dictate in which applications they can be used. As expected, higher performance thermoplastic elastomers are more expensive (Kear, 2003). A qualitative comparison of cost vs. performance is shown for various classes of thermoplastic elastomers in Figure 13.22. Styrenic block copolymers such as SBS and SEES are less costly than TPVs but have reduced oil resistance and lower maximum use temperatures. The advantage of SEES over SES with regard to temperature resistance is not... 

Glycidyl methacrylate copolymers Ethylene/butyl acrylate/maleic anhydride copolymers Styrene/ethylene-butylene/styrene block copolymer Poly(amide) (PA), MgO Silicone rubber and aminosilane Liquid crystalline polymers Improved impact strength Improved impact strength" Improved impact strength Improved electrical properties, in glass fiber applications" Improved mechanical properties" Viscosity reduction" ... 

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