Dicyclopentadiene copolymers

Ethylene/propylene/dicyclopentadiene copolymer Ethylene/propylene/ dicyclopentadiene copolymer rubber. See Ethylene/propylene/dicy-clopentadiene terpolymer... 

Synonyms Ethylene/propylene/dicyclopentadiene copolymer Ethylene/ propylene/dicyclopentadiene copolymer rubber Uses Reactive processing aid, modifier for elastomers and resins in food-pkg. adhesives rubber for food-contact articles for repeated use Regulatory FDA 21 CFR 175.105,177.2600 Trade Names Trilene 54... 

Ethylene/propylene copolymer, fluorinated. See Fluorinated ethylene/propylene Ethylene/propylene/dicyclopentadiene copolymer ... 

The low-molecular-weight, soluble copolymers, produced in dioxane or cyclohexanone at 80°C, contain MA in a 1 1 or 2 1 mole ratio, depending on the monomer feed composition. With a large excess (5 1) of dicyclopentadiene 1 1 copolymer is produced. A 2 1 MA-dicyclopentadiene copolymer is formed at higher temperatures (155°C) and/or in the presence of excess... 

Kuala Lumpur, 6th-9th Oct.1997, p.408-12. 012 SULPHUR/DICYCLOPENTADIENE COPOLYMERS AS VULCANISEVG AGENTS FOR RUBBER... 

Cyclic Polyolefins (GPO) and Gycloolefin Copolymers (GOG). Japanese and European companies are developing amorphous cycHc polyolefins as substrate materials for optical data storage (213—217). The materials are based on dicyclopentadiene and/or tetracyclododecene (10), where R = H, alkyl, or COOCH. Products are formed by Ziegler-Natta polymerization with addition of ethylene or propylene (11) or so-called metathesis polymerization and hydrogenation (12), (101,216). These products may stiU contain about 10% of the dicycHc stmcture (216). 

Ring-Opening Metathesis Polymerization. Several new titanacyclobutanes have been shown to initiate living ring-opening metathesis polymerization (ROMP) systems. These have been used to make diblock and triblock copolymers of norbomene [498-66-8] (N) and its derivatives (eg, dicyclopentadiene [77-73-6] (D)) (Fig. 2) (41). 

The isoprene units in the copolymer impart the ability to crosslink the product. Polystyrene is far too rigid to be used as an elastomer but styrene copolymers with 1,3-butadiene (SBR rubber) are quite flexible and rubbery. Polyethylene is a crystalline plastic while ethylene-propylene copolymers and terpolymers of ethylene, propylene and diene (e.g., dicyclopentadiene, hexa-1,4-diene, 2-ethylidenenorborn-5-ene) are elastomers (EPR and EPDM rubbers). Nitrile or NBR rubber is a copolymer of acrylonitrile and 1,3-butadiene. Vinylidene fluoride-chlorotrifluoroethylene and olefin-acrylic ester copolymers and 1,3-butadiene-styrene-vinyl pyridine terpolymer are examples of specialty elastomers. 

The first documented example of the living ROMP of a cycloolefin was the polymerization of norbornene using titanacyclobutane complexes such as (207) 510-512 Subsequent studies described the synthesis of di- and tri-block copolymers of norbornenes and dicyclopentadiene.513 However, functionalized monomers are generally incompatible with the highly electrophilic d° metal center. 

A copolymer consisting of three monomers polymerised together, e.g., ethylene-propylene-dicyclopentadiene terpolymer. 

The dicyclopentadiene terpolymer can give higher states of cure with peroxides than the copolymer, although in peroxide curing of both the copolymer and terpolymer it is common practice to add a coagent, to increase the state of cure. Triaryl isocyanurate or sulphur are the most common coagents. 

Copolymers and terpolymers of ethylene and propene, commonly known as EPM and EPDM polymers, respectively, are useful elastomers [Ver Strate, 1986], EPM and EPDM are acronyms for ethylene-propene monomers and ethylene-propene-diene monomers, respectively. The terpolymers contain up to about 4 mol% of a diene such as 5-ethylidene-2-norbomene, dicyclopentadiene, or 1,4-hexadiene. A wide range of products are available, containing 40-90 mol% ethylene. The diene, reacting through one of its double bonds, imparts a pendant double bond to the terpolymer for purposes of subsequent crosslinking (Sec. 9-2b). 

Commercial grades of ethylene-propylene copolymers (EPR) contain 60-75 mol% of ethylene to minimize crystallization. The addition of a third monomer, such as 1,4-hexadiene, dicyclopentadiene, or 5-ethylidene-2-norbornene, produces generally amorphous faster-curing elastomers. A large number of such terpolymers, referred to as EPDM, is available commercially. Their properties, performance, and response to radiation vary considerably depending on macrostructure, ethylene/propylene ratio, as well as on the type, amount, and distribution of the third monomer. 

As was mentioned, cycloaddition of unactivated hydrocarbons, namely, that of cyclopentadiene, has practical significance. 5-Vinyl-2-norbomene is produced by the cycloaddition of cyclopentadiene and 1,3-butadiene546,547 [Eq. (6.96)] under conditions where side reactions (polymerization, formation of tetrahydroindene) are minimal. The product is then isomerized to 5-ethylidene-2-norbomene, which is a widely used comonomer in the manufacture of an EPDM (ethylene-propylene-diene monomer) copolymer (see Section 13.2.6). The reaction of cyclopentadiene (or dicyclopentadiene, its precursor) with ethylene leads to norbomene548,549 [Eq. (6.97)] 550... 

With larger amount of propylene a random copolymer known as ethylene-propylene-monomer (EPM) copolymer is formed, which is a useful elastomer with easy processability and improved optical properties.208,449 Copolymerization of ethylene and propylene with a nonconjugated diene [EPDM or ethylene-propylene-diene-monomer copolymer] introduces unsaturation into the polymer structure, allowing the further improvement of physical properties by crosslinking (sulfur vulcanization) 443,450 Only three dienes are employed commercially in EPDM manufacture dicyclopentadiene, 1,4-hexadiene, and the most extensively used 5-ethylidene-2-norbomene. 

Although both linear polyethene and isotactic polypropene are crystalline polymers, ethene-propene copolymers prepared with the aid of Ziegler catalysts are excellent elastomers. Apparently, a more or less random introduction of methyl groups along a polyethene chain reduces the crystallinity sufficiently drastically to lead to an amorphous polymer. The ethene-propene copolymer is an inexpensive elastomer, but having no double bonds, is not capable of vulcanization. Polymerization of ethene and propene in the presence of a small amount of dicyclopentadiene or 1,4-hexadiene gives an unsaturated heteropolymer, which can be vulcanized with sulfur in the usual way. 

As recently as 1986 almost all addition polymers were excluded from the ranks of engineering plastics. However, progress since then has been made in the development of addition polymeric resins such as polymethylpentene and polycyclopentadiene and its copolymers (see CYCLOPENTADIENE AND dicyclopentadiene). 

The polymerization of norbornene, Eq. (19), is stopped by cooling the reaction mixture to room temperature. The active polymer 11 can be stored for long periods of time. Heating 11 to temperatures above 65 °C in the presence of monomer causes renewed chain propagation. The subsequent addition of different cyclic olefins, such as endo- and exo-dicyclopentadiene, benzonorbomadiene and 6-methylbenzonorbornadiene resulted in the formation of well-defined AB- and ABA-type block copolymers, Eq. (21) [38]. Triblock copolymers 13 with narrow molecular weight distributions (polydispersity = 1.14) were prepared. Thus, the living character enables the preparation of new uniform block copolymers of predictable composition, microstructure and molecular weight. 

Sulfur is used directly in sulfur-additive solutions which are used as coatings (3, 4, 5, 6). Dicyclopentadiene is a potentially cheap material that can form copolymers with liquid sulfur. The patent literature reports applications of the sulfur-dicyclopentadiene system in sprayable coatings, rubber vulcanizates, etc. However, very little has been written on the chemistry, characterization, and properties of this system. 

Of great industrial interest are the copolymers of ethene and propene with a molar ratio of 1/0.5, up to 1/2. These EP-polymers show elastic properties and, together with 2-5 wt% of dienes as third monomers, they are used as elastomers (EPDM). Since they have no double bonds in the backbone of the polymer, they are less sensitive to oxidation reactions. As dienes, ethylidenenorbomene, 1,4-hexadiene, and dicyclopentadiene are used. In most technical processes for the production of EP and EPDM rubber in the past, soluble or highly disposed vanadium components are used [69]. Similar elastomers can be obtained with metallocene/MAO catalysts by a much higher activity which are less colored [70-72]. The regiospecificity of the metallocene catalysts toward propene leads exclusively to the formation of head-to-tail enchainments. The ethylidenenor-bornene polymerizes via vinyl polymerization of the cyclic double bond and the tendency to branching is low. The molecular weight distribution of about 2 is narrow [73]. 

When ethylene is copolymerized with substantial amounts (>25%) of propylene an elastomeric copolymer is produced, commonly known as ethylene-propylene rubber (EPR) or ethylene-propylene monomer (EPM) rubber. When a diene, such as dicyclopentadiene, is also included, a terpolymer known as ethylene-propylene-diene monomer (EPDM) rubber is obtained. EPR and EPDM are produced with single site and Ziegler-Natta catalysts and are important in the automotive and construction industries. However, EPR and EPDM are produced in much smaller quantities relative to polyethylene. Elastomers display vastly different properties than other versions of industrial polyethylene and are considered outside the purview of this text. EPR and EPDM will not be discussed further. 

The relative stability of the two structures seems to be determined by entropic factors. The increase in the size of the olefin substituent [32-35] or of the number of substituents, e.g., cychc olefins such as norbornene [36] or dicyclopentadiene [4], leads to the stabilization of the spiroketal structure, which can survive even in solution. However, a precise determination of the relative stabihty has not been reported. As far as the growing of the copolymer chain is concerned, the mechanistic role, if any, of the spiroketal structure is still not very clear [4, 30]. It is noteworthy that the copolymers are, for the most part, isolated in the spiroketal structure when the copolymerization reaction is regio- and stereoregular. 

Matyjaszewski et al. demonstrated that living ring opening metathesis polymerization (ROMP) could also be combined with ATRP to produce novel block copolymers [292]. ROMP of norbornene (NB) and dicyclopentadiene (CPD) were performed using an Mo-alkylidene complex, followed by reaction with p-(bro-momethyl) benzaldehyde to generate a benzyl bromide terminated polymer capable of being used as a macroinitiator for ATRP (Scheme 41). 

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