Ethylene-propylene, conjugated

The base-catalyzed reaction of alkylaromatics with olefins is unique in that it allows the size of the alkyl group of an arylalkane to be increased. Arylalkanes suitable for this reaction are those which contain a benzylic hydrogen. The olefins most useful for this reaction are ethylene, propylene, conjugated alkadienes, and styrene and its derivatives. Sodium and potassium are very effective catalysts. Sodium usually requires the presence of a chain precursor to initiate the reaction. 

Conjugation as well as geometric and positional isomerization occur when an alkadienoic acid such as linoleic acid is treated with a strong base at an elevated temperature. CycHc fatty acids result from isomerization of linolenic acid ia strong base at about 250°C (58). Conjugated fatty acids undergo the Diels-Alder reaction with many dienophiles including ethylene, propylene, acryUc acid, and maleic anhydride. 

The most important olefins and diolefins used to manufacture petrochemicals are ethylene, propylene, butylenes, and hutadiene. Butadiene, a conjugated diolefin, is normally coproduced with C2-C4 olefins from different cracking processes. Separation of these olefins from catalytic and thermal cracking gas streams could he achieved using physical and chemical separation methods. However, the petrochemical demand for olefins is much greater than the amounts these operations produce. Most olefins and hutadienes are produced hy steam cracking hydrocarbons. 

The first results of anionic polymerization (the polymerization of 1,3-butadiene and isoprene induced by sodium and potassium) appeared in the literature in the early twentieth century.168,169 It was not until the pioneering work of Ziegler170 and Szwarc,171 however, that the real nature of the reaction was understood. Styrene derivatives and conjugated dienes are the most suitable unsaturated hydrocarbons for anionic polymerization. They are sufficiently electrophilic toward carbanionic centers and able to form stable carbanions on initiation. Simple alkenes (ethylene, propylene) do not undergo anionic polymerization and form only oligomers. Initiation is achieved by nucleophilic addition of organometallic compounds or via electron transfer reactions. Hydrocarbons (cylohexane, benzene) and ethers (diethyl ether, THF) are usually applied as the solvent in anionic polymerizations. 

EPDM terpolymers of ethylene, propylene, and a small percentage of a non-conjugated diene, which makes the side chains unsaturated. 

Coordination polymerisation via re complexes comprises polymerisation and copolymerisation processes with transition metal-based catalysts of unsaturated hydrocarbon monomers such as olefins [11-19], vinylaromatic monomers such as styrene [13, 20, 21], conjugated dienes [22-29], cycloolefins [30-39] and alkynes [39-45]. The coordination polymerisation of olefins concerns mostly ethylene, propylene and higher a-olefins [46], although polymerisation of cumulated diolefins (allenes) [47, 48], isomerisation 2, co-polymerisation of a-olefins [49], isomerisation 1,2-polymerisation of /i-olcfins [50, 51] and cyclopolymerisation of non-conjugated a, eo-diolefins [52, 53] are also included among coordination polymerisations involving re complex formation. 

The only important industrial applications of such soluble catalysts are of those prepared from VC14, VOCl3, V(Acac)3, VO(OEt)Cl2, VO(OEt)2Cl, VO(OEt)3 or VO(OBu)3 as precursors and AlEt3, AlEt2Cl or AI(/-Buj2CI as activators, in heptane solution, by which ethylene/propylene copolymers and ethylene/propylene/non-conjugated diene terpolymers are produced [72]. The AW molar ratio in these catalysts does not usually exceed a value of 3 1. 

Random ethylene/propylene copolymers are amorphous and represent an interesting class of synthetic elastomers. The introduction of double bonds, useful for sulphur vulcanisation in the copolymer, can be achieved by copolymerisation of ethylene and propylene with non-conjugated dienes containing only one double bond capable of insertion for instance, 1,4-hexadiene, dicy-clopentadiene and 5-ethylidene-2-norbornene (endocyclic double bond)... 

Explain why 1,4-hexadiene, but not 1,5-hexadiene, is used for obtaining ethylene/ propylene/non-conjugated diene vulcanisable terpolymers. 

Important copolymerizations with Ziegler-Natta catalysts are between hydrocarbon monomers. An example is the reaction of ethylene, propylene, and a non-conjugated diene, such as 5-ethylidene-2-norbornene, to produce the so-called EPDM (ethylene-propylene-diene monomer) elastomers. These products have... 

Table 1. Trienes used in the synthesis of ethylene-propylene based terpolymers containing conjugated diene systems... 

In literature there are data on the homogeneous thermal addition of trichlorosilane to aliphatic and cyclic alkenes as well as to alkodienes with isolated and conjugated double bonds which proceeds under high pressures at 280-300°C [161-163]. Voronkov et al. [164] succeeded in carrying out the thermal addition of trichlorosilane to phenylacetylene in a polar solvent at 200°C while without the solvent the reaction proceeds at 500°C. The authors of Refs.[27,165] have performed the addition of ethylene, propylene, butene, butadiene, octene to silica surface at elevated temperatures. These chemical processes may be referred to as reactions of solid-phase thermal hydrosilylation. Unfortunately, these works have not received a large development effort. 

In order to overcome this drawback, new types of multi-unsaturated hydrocarbon monomers have been synthesized in recent years and their behavior in ethylene-propylene copolymerization has been extensively studied. Such monomers are characterized by the presence of one unconjugated double bond suitable for copolymerization and of a system of two or three conjugated double bonds, the high reactivity of which makes them competitive with conventional diene rubbers in sulfur vulcanization despite their low concentration. 

Atactic poly(methyl methacrylate) Atactic polystyrene Butyl-rubber Chlorinated polyethylene Deuterated high density polyethylene Ethylene butylacrylate Elastomeric copolymer from ethylene and ethyl acrylate Elastomeric terpolymer from ethylene, propylene and a non-conjugated diene Elastomeric ethylene-propylene... 

The acceptor-Lewis acid complex reaets with conjugated donor molecules (e.g., styrene) under quite mild conditions to produce highly alternating structures. However, much stronger conditions are required for nonconjugated donor molecules (ethylene, propylene, vinyl acetate, etc.), where it is necessary to use alkyl aluminum sesquichloride as the Lewis acid at a temperature of 195 K. It has been postulated that a ternary molecular complex is formed... 

Triple ethylene-propylene rubbers of SKEP(T) brands contain up to several percents of non-conjugated dienes predominantly dicyclopentadiene (DCPD) and ethylidennorbomene (ENB) as third comonomers [177]. 

Orientations in elongated mbbers are sometimes regular to the extent that there is local crystallization of individual chain segments (e.g., in natural rubber). X-ray diffraction patterns of such samples are very similar to those obtained from stretched fibers. The following synthetic polymers are of technical relevance as mbbers poly(acrylic ester)s, polybutadienes, polyisoprenes, polychloroprenes, butadiene/styrene copolymers, styrene/butadiene/styrene tri-block-copolymers (also hydrogenated), butadiene/acrylonitrile copolymers (also hydrogenated), ethylene/propylene co- and terpolymers (with non-conjugated dienes (e.g., ethylidene norbomene)), ethylene/vinyl acetate copolymers, ethyl-ene/methacrylic acid copolymers (ionomers), polyisobutylene (and copolymers with isoprene), chlorinated polyethylenes, chlorosulfonated polyethylenes, polyurethanes, silicones, poly(fluoro alkylene)s, poly(alkylene sulfide)s. 

Pinenes have also been used as feedstock to prepare several linear non-conjugated non-terpenic dienes (e.g. 3,7-dimethyl-l,6-octa-l,6-diene and 5,7-dimethylocta-l,6-diene) used in the synthesis of elastomeric ethylene-propylene-diene terpolymers [14]. 

EPT, EPTR Ethylene, propylene, and a non-conjugated diene terpolymer, also EPDM... 

EPDM n. Elastomer from ethylene, propylene, and a diene. Abbreviation for elastomeric terpolymer from ethylene, propylene, and a conjugated diene. 

A modified ethylene/propylene/non-conjugated diene (EPDM) elastomer, Royaltuf X330 (Uniroyal Chemical), is offered as a toughness improver for PBT and produced as a finely dispersed phase, for easy processing. 

Composition Maleic anhydride modified ethylene/propylene/ non-conjugated diene elastomer Physical Form Rubber Pellets Specific Gravity 0.85 Total Maleic Anhydride/Acid 0.5%... 

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