Dicyclopentadienes copolymerization

Sulfur—Dicyclopentadiene Copolymeric Material as Compared with Plastic Sulfur... 

Dicyclopentadiene is also polymerized with tungsten-based catalysts. Because the polymerization reaction produces heavily cross-Unked resins, the polymers are manufactured in a reaction injection mol ding (RIM) process, in which all catalyst components and resin modifiers are slurried in two batches of the monomer. The first batch contains the catalyst (a mixture of WCl and WOCl, nonylphenol, acetylacetone, additives, and fillers the second batch contains the co-catalyst (a combination of an alkyl aluminum compound and a Lewis base such as ether), antioxidants, and elastomeric fillers (qv) for better moldabihty (50). Mixing two Uquids in a mold results in a rapid polymerization reaction. Its rate is controlled by the ratio between the co-catalyst and the Lewis base. Depending on the catalyst composition, solidification time of the reaction mixture can vary from two seconds to an hour. Similar catalyst systems are used for polymerization of norbomene and for norbomene copolymerization with ethyhdenenorbomene. 

Ethylene—Propylene Rubber. Ethylene and propjiene copolymerize to produce a wide range of elastomeric and thermoplastic products. Often a third monomer such dicyclopentadiene, hexadiene, or ethylene norbomene is incorporated at 2—12% into the polymer backbone and leads to the designation ethylene—propylene—diene monomer (EPDM) mbber (see Elastomers, synthetic-ethylene-propylene-diene rubber). The third monomer introduces sites of unsaturation that allow vulcanization by conventional sulfur cures. At high levels of third monomer it is possible to achieve cure rates that are equivalent to conventional mbbers such as SBR and PBD. Ethylene—propylene mbber (EPR) requires peroxide vulcanization. 

The molybdenum-based catalyst MoOCl2(t-BuO)2 has been used to copolymerize norbornene and dicyclopentadiene (20). The polymeric product exhibits a single peak in gel permeation chromatography. 

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. 

Plastic Sulfur Stabilization by Copolymerization of Sulfur with Dicyclopentadiene... 

Liquid sulfur-dicyclopentadiene (DCP) solutions at 140°C undergo bulk copolymerization where the melt viscosity and surface tension of the solutions increase with time. A general melt viscosity equation rj == tj0 exp(aXH), at constant temperature, has been developed, where tj is the viscosity at time t for an S -DCP feed composition of DCP mole fraction X and rj0 (in viscosity units), a (in time 1), and b (a dimensionless number, -f- ve for X < 0.5 and —ve for X > 0.5) are empirical constants. The structure of the sul-furated products has been analyzed by NMR. Sulfur non-crystallizable copolymeric compositions have been obtained as shown by thermal analysis (DSC). Dodecyl polysulfide is a viscosity suppressor and a plasticizer for the S8-DCP system. 

Dicyclopentadiene (boiling point for both the isomers is 170°C) is soluble in liquid sulfur at 140°C in all proportions, and the melt viscosity of the sulfur-DCP solution increases with time because of a copolymerization reaction. The DSC thermograms of sulfur-DCP mixtures are shown in Figure 1. The exothermic reaction clearly becomes evident with a feed of about 20% DCP with the exotherm starting at about 140°C. 

The behavior of melt viscosity of sulfur-dicyclopentadiene solutions is of obvious interest from the point of sprayable coatings. The melt viscosity behavior has been reported recently, but only qualitatively and over a narrow range of compositions (18). The viscosity of sulfur measured by the capillary method by Bacon and Fanelli (19, 20) is considered to be the best (21). Recently, however, the viscosity of sulfur has been measured by an apparatus containing an electric motor and a rotating cylinder (22). Viscosity of the sulfur-DCP solutions are measured here with the help of a Brookfield synchro-lectric viscometer, which is of the later kind. Viscosity measurements have been carried out to follow the copolymerization reaction and to analyze the viscosity behavior. 

R = CH3, CH2SiMe3),96 VO(CH2SiMe3)3, [(Me3CCH2)3V]2(/J,-N2),97 and [V(mes)3(THF)] are all isolable. The latter is a convenient starting material because it is easily prepared and reacts readily with protic sources such as a-amino acids.98 Unstable alkyls are present in the solutions of vanadium oxides or halides and A1 alkyls,99 which are used in the Ziegler-Natta type reaction for the copolymerization of styrene, butadiene, and dicyclopentadiene to give synthetic rubbers. 

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. 

Homogeneous vanadium-based catalysts formed by the reaction of vanadium compounds and reducing agents such as organoaluminum compounds [10-12] are used industrially for the production of elastomers by ethylene/propene copolymerization (EP rubber) and ethylene/propene/diene terpolymerization (EPDM rubber). The dienes are usually derivatives of cyclopentadiene such as ethylidene norbomene or dicyclopentadiene. Examples of catalysts are Structures 1-4. Third components such as anisole or halocarbons are used to prevent a decrease in catalyst activity with time which is observed in the simple systems. 

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. 

Other catalytic systems were used recently, namely a Ddppi system (67, Scheme 8.14) for dicyclopentadiene and di(methylcyclopentadiene) [96] and imino-phosphine complexes (Scheme 8.19, 97 and 98) or hybrid terdentate carbene hgand complexes (99) [133] for norbornene. Furtlierrnore, the copolymerization of various substituted norbomadienes and norbomenes has been achieved with Rh6(CO)i6 under water gas shift reaction conditions (55 ""C, water and 100 atm CO) [134],... 

An important extension of Ziegler-Natta polymerization is the copolymerization of styrene, butadiene and a third component such as dicyclopentadiene or 1, 4-hexadiene to give synthetic rubbers. Vanadyl halides rather than titanium halides are then used as the metal catalyst. 

The use of comonomers, including cross-linking agents, in the ROMP of dicyclopentadiene is described in Section 17.11. Numerous references to other metathesis copolymerization systems can be found in the patent literature. 

Copolymerization of ethylene with propylene results in a random, noncrystalline copolymer that is a chemically inert and rubbery material. EPM is a saturated copolymer that can be cross-linked through the combination of the free radicals generated by peroxides or radiation. To incorporate sites for vulcanization, an unsaturated terpolymer can be prepared from ethylene, propylene, and a small amount (3 to 9%) of a nonconjugated diene (EPDM). The diene is either dicyclopentadiene, ethylidene nor-bomene, or 1,4-hexadiene. The resulting unsaturated terpolymer can be vulcanized by traditional techniques. Each of the termonomers confers different characteristics on the final elastomer. 

From other p<%olefins, photocrossiinking of ethylene propylene da omers, copolymerized with dienes such as dicyclopentadiene, 1.4-hexadiene, and 5-ethylidene... 

Copolymerization of ethylene and propylene produces an elastomeric polymer that is virtually inert because of the absence of carbon-carbon double bonds (EPM). Such polymers thus tend to be crossUnked with peroxides or by radiation. To improve the reactivity of ethylene-propylene copolymers, 1-10% of a third monomer can be added to give a terpolymer or ethylene-propylene-diene monomer (EPDM). The primary diene monomers used in EPDM are 1,4-hexadiene, dicyclopentadiene, and ethyUdene norbomene. Introduction of an unsaturated monomer such as ethylidene norbomene will enable use of sulfur-based crosslinking systems. 

Ethylene-propylene copolymers (EPDM) are, by their random copolymerization, amorphous in structure and therefore easily halogenated. EPDM has been chlorinated to improve its properties and cocurability with other rubbers. The chlorination was directed toward the termonomer dicyclopentadiene to form the allylic chloride (Schoen et al., 1975). In this manner, EPDM was chlorinated, and the resulting products had improved properties. 

Dimethylnorbomene ester (DNE) has been used as a cohealing agent, which copolymerizes with dicyclopentadiene (DCPD). DCPD can form a hydrogen bond with an epoxy matrix (Fig. 18) [73]. Dimethylphthalate (DMP) is structurally... 

The copolymerization of ethylene with larger amounts of dicyclopentadiene with, for example, vanadium trisacetyl acetonate/AlR3 as catalyst, leads to polymers with isolated double bonds. They oxidize at room temperature to insoluble cross-linked films. They can be cross-linked with phenol/formaldehyde resins and blended with them. 

The reaction with MA is characteristic for the unsaturated compounds. As a result it is applied to liquid polydienes, to cyclopentadiene and dicyclopentadiene oligomers, to copolymeric aliphatic resins, and to cycloaliphatic resins. 

A variety of nonconjugated bicyclodienes, where the olefin residues are part of two fused rings, such as dicyclopentadiene, or part of two separate but connected rings, such as l,l -bicyclopent-2,2 -ene, have been investigated in copolymerization studies with MA. 

Dicyclopentadiene is claimed to readily undergo equimolar cyclocopoly-merization with MA, with free-radical initiators at temperatures below Above 170°C, dissociation of dicyclopentadiene occurs, giving terpolymers of cyclopentadiene, dicyclopentadiene, and MA. " Bulk copolymerization produces mainly insoluble polymer. Copolymerizations in dioxane or cyclohexanone, where the solvent concentration is at least 25%, produces copolymers that are 100% soluble in polar solvents. 

Two derivatives of dicyclopentadiene, i.e., 3-isopropylidene dicyclopen-tadiene 59 and its 9,10-dihydro derivative 60 undergo spontaneous alternating copolymerization with In both cases, equimolar copolymers are... 

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