Ethylene/propylene copolymers elastomers based

An oil-based drilling mud can be viscosified with maleated ethylene-propylene elastomers [919]. The elastomers are ethylene-propylene copolymers or ethylene-propylene-diene terpolymers. The maleated elastomers are far more effective oil mud viscosifiers than the organophilic clays used. On the other hand, specific organophilic clays can provide a drilling fluid composition less sensitive to high temperatures [491]. 

The Ziegler-Natta catalysts have acquired practical importance particularly as heterogeneous systems, mostly owing to the commercial production of linear high- and low-density polyethylenes and isotactic polypropylene. Elastomers based on ethylene-propylene copolymers (with the use of vanadium-based catalysts) as well as 1,4-cz s-and 1,4-tran.y-poly(l, 3-butadiene) and polyisoprene are also produced. These catalysts are extremely versatile and can be used in many other polymerisations of various hydrocarbon monomers, leading very often to polymers of different stereoregularity. In 1963, both Ziegler and Natta were awarded the Nobel Prize in chemistry. 

FIGURE 9.17 Dependence of productivity and separation factor /3p C6H5CH3/H2O of membranes based on various rubbery polymers on the glass transition temperature of the polymer (pervaporation separation of saturated toluene/water mixture, T = 308 K) (1) polydimethyl siloxane (2) polybutadiene (3) polyoctylmethyl siloxane (4) nitrile butadiene rubber with 18% mol of nitrile groups (5) the same, 28% mol of nitrile groups (6) the same, 38% mol of nitrile groups (7) ethylene/propylene copolymer (8) polyepichlorohydrin (9) polychloroprene (10) pol3furethane (11) polyacrylate rubber (12) fluorocarbon elastomer. (From analysis of data presented in Semenova, S.I., J. Membr. Sci., 231, 189, 2004. With permission.)... 

Composition (type of polymeric components). The base polymer (which is to be modified) may be an amorphous polymer [e.g., polystyrene (PS), styrene-acrylonitrile copolymer, polycarbonate, or poly(vinyl chloride)], a semicrystalline polymer [e.g., polyamide (PA) or polypropylene (PP)], or a thermoset resin (e.g., epoxy resin). The modifier may be a rubber-like elastomer (e.g., polybutadiene, ethylene-vinyl acetate copolymer, ethylene-propylene copolymer, or ethylene-propylene-diene copolymer), a core-shell modifier, or another polymer. Even smaller amounts of a compatibilizer, such as a copolymer, are sometimes added as a third component to control the morphology. 

IV to VIII metals and base metal alkyls of Group II or III metals (Penczek and Premia, 2012 Boor, 1979 Ciardelli, 1992). It arose from the spectacular discovery of Ziegler et al. (1955) that mixtures of titanium tetrachloride and aluminum alkyls polymerize ethylene at low pressures and temperatures and from the equally spectacular discovery by Natta (1955) that the Ziegler catalysts can stereospecifically polymerize monoolefins to produce tactic, crystalline polymers. As can be imagined, these systems can involve many combinations of catalyst components, not all of which are catalytically active or stereospecific. However, we shall be concerned here only with polymerizations involving the commercial elastomers, principally polyisoprene, polybutadiene (Duck and Locke, 1977 Zohuri et al., 2012 Teyssie et al., 1988), and the ethylene-propylene copolymers (Schobel et al., 2012 Ver Strate, 1986 Davis et al., 1996 Noordermeer, 2003 Baldwin and Strate, 1972). 

Ethylene/propylene copolymerization is of significant commercial importance. Elastomers formed from random ethylene/propylene copolymers (EP) possess a number of valuable properties including a high plateau modulus ( 1.6 MPa), which permits a higher filler loading and more cost-effective compounding. Furthermore, of the major hydrocarbon-based rubbers, EP is by far the least reactive with oxygen and ozone. 

All these elastomers, especially poly thylene-fo-butylene) and poly(ethylene- -propylene), are nonpolar. The corresponding block copolymers can thus be compounded with hydrocarbon-based extending oils, but do not have much oil resistance. Conversely, block copolymers with polar polyester or polyether elastomer segments have litde affinity for such hydrocarbon oils and so have better oil resistance. 

A base polymer, such as an ethylene-propylene (EP) copolymer, can be acquired in a range of compositions, molecular weights, various ethylene-to-propylene ratios, various molecular weight distributions, and a range of densities. Each of these variations results in a base polymer that has specific practical properties such as flexibility, elastic recovery, tensile strength and thermal limit to name a few. As a base polymer, ethylene-propylene polymers and most other non-crosslinked elastomers have no significant commercial application, since they are essentially a liquid with veiy high viscosity. 

It is claimed that styrene/butadiene diblock polymers bring about an improvement in the hardness, strength, and processability of polybutadiene elastomers (27), as well as an improvement in the ozone resistance of neoprene rubber (28). Styrene diblock polymers have also been made with isoprene, a-methyIstyrene, methyl methacrylate, vinylpyridine, and a-olefins. Block copolymers of ethylene, propylene, and other a-olefins with each other have been made as well. Heteroatom block copolymers based on styrene or other hydrocarbons and alkylene oxides, phenylene oxides, lactones, amides, imides, sulfides, or slloxanes have been prepared. 

Multi-Flex TPE G 7680 [Multibase http //www.multibase.com], Multi-Flex TPE G 7890 [Multibase http //www.multibase.com], Multi-Flex TPE G 7940 t[Multibase http //www.multibase.com], Multi-Flex TPE RP-6568 B2 [Multibase http //www.multibase.com], Multi-Flex TPE RP-6568 C [Multibase http //www.multibase. com] Styrene-ethylene-propylene block copolymer Uses Thermoplastic elastomer used as a modifier in solv.-based weatherable sealants Trade Name Synonyms Kraton G 1701 t[Kraton Polymers http //www.kraton.com], Kraton G 1701X [Kraton Polymers http //www.kraton.com]-, Kraton G 1702X [Kraton Polymers http //www.kraton.com]... 

Copolymers of ethylene and propylene show, in some cases, elastic properties (324,325). Further incorporation of dienes, such as ethylidenenorbomene or 1,4-hexadiene, produces ethylene-propylene-diene monomer (EPDM) elastomers. Kaminsky (326) and Waymouth (327) have reported the predominantly alternating copolymerization of ethylene and propylene, using Ci and Cg symmetric (cyclopentadienyD(fluorenyl) aasa-zirconocene-based catalysts (eq. 3), demonstrating yet another example of preparation of new materials through rational exploitation of SSC systems. 

An important saturated elastomer is based on a random copolymer of ethylene and propylene, EPDM, or ethylene-propylene-diene monomer. The diene is often a bicycUc compound introduced at the 2% level to provide cross-linking sites ... 

The polyolefins are those polymers based only on carbon and hydrogen, originating from monomers containing a double bond in the 1-position, sometimes called a-olefins. Principally, these include polyethylene, polypropylene, copolymers of polyethylene containing various comonomers such as 1-butene, 1-hexene, and 1-octene, ethylene-propylene monomer (EPM), and ethylene-propylene-diene-monomer (EPDM). All of these are plastics except EPM and EPDM, which are elastomers. 

In the examination of potential applications for these unique materials that possess a wide variety of properties depending on copolymer composition, the Dow group examined finished articles formed by injection and blow molding, blown and cast film and melt extrusion. Potential applications for these new materials would be as substitute materials for flexible PVC, styrenic block copolymers, ethylene/vinyl acetate copolymers and ethylene/propylene-based elastomers. These new ethylene/styrene copolymers once again demonstrate that new catalyst technology creates new markets and applications for the polyethylene industry by competing with materials outside of the polyethylene product mix. 

Other elastomer blends of commercial utility have been cited in the literature [96-98]. Polyolefin blends have been utilized in many forms to achieve modifications yielding environmental stress rupture resistance and to improve impact strength, flexibility, and filler acceptance [99,100]. The addition of ethylene-propylene rubber (EPR) or blends of EPR and high-density PE to PP has been specifically utilized for improving the low-temperature impact strength [101]. Low-modulus materials can be produced from EPR-PP blends containing more than 50% of EPR. These products include those under the trade names TPR, Somel, and Telcar [102-105]. Addition of rubber inclusion has been shown to yield definite improvements in the environmental stress rupture resistance [106]. Other examples of commercial rubber-based blends are impact-PS, ABS and bisphenol A polycarbonate blends and polysulfone blends made of a block copolymer of polysulfone and nylon 6 [107]. 

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