EPDM rubber monomers polymer

FIGURE 12.7 Monsanto rheometric curves of ethylene-propylene-diene monomer (EPDM) rubber-melamine fiber composites [64]. A, gum compound B, compound containing 30 phr melamine fiber but no dry bonding system and C, compound containing both dry bonding system and 30 phr melamine fiber. (From Rajeev, R.S., Bhowmick, A.K., De, S.K., Kao, G.J.P., and Bandyopadhyay, S., Polym. Compos., 23, 574, 2002. With permission.)... 

Radiation Treatment NVP, 2-hydroxyethylmethacrylate (HEMA), and acrylamide (AAm) have been grafted to the surface of ethylene-propylene-diene monomer (EPDM) rubber vulcanizates using the radiation method (from a Co 7 source) to alter surface properties such as wettability and therefore biocompatibility [197]. Poncin-Epaillard et al. [198] have reported the modification of isotactic PP surface by EB and grafting of AA onto the activated polymer. Radiation-induced grafting of acrylamide onto PE is very important... 

Ethylene—Propylene Rubber. Ethylene and propylene 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) rubber (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 rubbers such as SBR and PBD. Ethylene—propylene rubber (EPR) requires peroxide vulcanization. 

A common example of a copolymer is an ethylene-propylene copolymer. Although both monomers would result in semi-crystalline polymers when polymerized individually, the melting temperature disappears in the randomly distributed copolymer with ratios between 35/65 and 65/35, resulting in an elastomeric material, as shown in Fig. 1.19. In fact, EPDM rubbers are continuously gaining acceptance in industry because of their resistance to weathering. On the other hand, the ethylene-propylene block copolymer maintains a melting temperature for all ethylene/propylene ratios, as shown in Fig. 1.20. 

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]. 

These polyolefin rubbers are produced in two main types the saturated co-polymers, ethylene propylene rubber (EPM), and the unsaturated ethylene-propylene diene terpolymer (EPDM). The monomers are co-polymerised in ziegler natta type catalysts. The EPDM types are capable of sulfur vulcanisation as they contain, in addition to olefins, a non coagulated diene as the third monomer. 

Van Gisbergen, J. G. M., Hoeben, W. F. L. M., Meijer, H. E. H., Melt rheology of electron-beam-irradiated blends, of polypropylene and ethylene-propylene-diene monomer (EPDM) rubber. Polymer Engineering and Science 1991,31,1539-1544. 

Ethylene propylene diene monomer rubber (EPDM) Butyl rubber Perfluorinated polymers Low polarity Silicone... 

FKMs are coextruded with lower-cost copolymers such as etliylene acrylic copolymer. They can be modihed by blending and vulcanizing with other synthetic rubbers such as silicones, ethylene propylene rubber (EPR) and ethylene propylene diene monomer (EPDM) rubbers, epichlorohydrin, and nitriles. Fluoroelastomers are blended with modihed nitrile butadiene rubber (NBR) to obtain an intermediate performance-cost balance. These blends are useful for underhood applications in environments outside the engine temperature zone such as timing chain tensioner seals. Fluoroelastomers can also be blended with fluorosilicones and other high-temperature polymers to meet engine compartment environments and cost-performance balance. 

The long established use of accelerated sulphur systems for vulcanization of general purpose rubbers has always led to a reluctance of rubber processors to accept alternative vulcanization systems unless this was absolutely necessary. This is not simply innate conservatism but as much due to the anticipation of problems of contamination of stocks during processing and of difficulties in reclaiming. For this reason modified ethylene-propylene rubbers were developed in which units from a third monomer were present and which provided unsaturation in the polymer (EPDM rubbers). These termonomers, invariably dienes, used in amounts of 3-8% of the total monomer weight are generally expensive, relative to more common monomers and adversely affect the price structure but nevertheless the EPDM type of rubber is now dominant over the EPM copolymers. 

The polymerization of olefins with coordination catalysts is performed in a large variety of polymerization processes and reactor configurations that can be classified broadly into solution, gas-phase, or slurry processes. In solution processes, both the catalyst and the polymer are soluble in the reaction medium. These processes are used to produce most of the commercial EPDM rubbers and some polyethylene resins. Solution processes are performed in autoclave, tubular, and loop reactors. In slurry and gas-phase processes, the polymer is formed around heterogeneous catalyst particles in the way described by the multigrain model. Slurry processes can be subdivided into slurry-diluent and slurry-bulk. In slurry-diluent processes, an inert diluent is used to suspend the polymer particles while gaseous (ethylene and propylene) and liquid (higher a-olefins) monomers are fed into the reactor. On the other hand, only liquid monomer is used in the slurry-bulk pro-... 

Rubbers are polymers with large engineering application areas. The weathering oxidation progresses in the elastomers according with the namre of substrate. A comparison between styrene-butadiene mbber (SBR), ethylene-propylene-diene monomer (EPDM), chloroprene mbber (CR) and natural rabber (NR) [109] allowed stating some relevant outlines ... 

Delor-Jestin, F., Lacoste, J., Barrois-Oudin, N., Cardinet, C., Lemaire, J. Photo-, thermal and natural ageing of ethylene-propylene-diene monomer (EPDM) rubber used in automotive applications. Influence of carbon black, crosslinMng and stabilizing agents. Polym. Degrad. Stab. 67, 467-477 (2000)... 

Olefinic thermoplastic elastomer (TPO) materials are defined as compounds (mixfures) of various polyolefin polymers, semicrysfalline thermoplastics, and amorphous elastomers. Most TPOs are composed of polypropylene and a copolymer of ethylene and propylene called ethylene-propylene rubber (EPR) [10]. A common rubber of this type is called ethylene-propylene diene monomer (EPDM) rubber, which has a small amount of a third monomer, a diene (two carbon-carbon double bonds in it). The diene monomer leaves a small amount of unsaturation in the polymer chain that can be used for sulfur cross-linking. Like most TPEs, TPO products are composed of hard and soft segments. TPO compounds include fillers, reinforcements. 

A variety of situations call for the identification of polymers. A customer wishes to paint or glue an item or to use an object in a novel environment. It may be awkward or impossible to obtain the composition from the supplier. In another common case, it may simply be detective work to find a chemical reason why a competitor s product behaves differently from your own. Contaminants in fabrication plants can be very hard to trace. For example, a small amount of a highly unsaturated polymer, such as natural rubber, can prevent the proper cross-linking of a large amount of a more saturated material, such as butyl or ethylene propylene diene monomer (EPDM) rubber. 

Whilst the ASA materials are of European origin, the AES polymers have been developed in Japan and the US. The rubber used is an ethylene-propylene terpolymer rubber of the EPDM type (see Chapter 11) which has a small amount of a diene monomer in the polymerisation recipe. The residual double bonds that exist in the polymer are important in enabling grafting with styrene and acrylonitrile. The blends are claimed to exhibit very good weathering resistance but to be otherwise similar to ABS. 

FIGURE 38.6 Morphology of (a) ethylene-propylene-diene monomer (EPDM)-poly(ethylene-co-acrylic acid) blend (b) EPDM-poly(ethylene-co-acrylic acid)-ground rubber tire (GRT) blend. (Reprinted from Naskar, A.K., Bhowmick, A.K., and De, S.K., Polym. Eng. Sci., 41, 1087, 2001. With permission from Wiley InterScience.)... 

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