EPDM,

Ethylene-propylene diene monomer (EPDM) rubbers are used in mass predominantly in isolation systems such as CRFM (condenser, radiator, fan module) or engine mounting. More varied are the sealing applications, which include transmission seals and o-rings, HVAC module seals and gaskets, radiator seals, weather stripping 

Ethylene and propylene monomers combine to form the saturated and stable backbone [4], This saturated backbone will provide excellent heat, oxidation, ozone, and weather aging because no reactive double bonds are in the backbone structure [4], The third monomer (ENB) is added in a controlled manner and provides a site for cross-linking via the double bond. The M in EPDM refers to a saturated backbone. By virtue of the ENB, various amounts of vulcanization can be obtained to acquire the durometer, tear strength and tensile and other properties needed for the sealing or isolation needs of the automobile part. 

Termonomer Cure and Property Features Long Chain Branching 

ENB Fastest and highest state of cure good tensile Low to moderate 

DCPD Slow sulfur cure good compression set High 

The majority of these systems are crosslinked, so are thermosets. The term thermoplastic vulcanisates (TPV) is also used (a.8). Copolymers are made from ethylene, propylene and a small fraction of unsaturated diene, so allowing the crosslinking of the foam. Eor applications such as mouse mats, the foam density is 

Variation of initial compressive yield stress of ESI/LDPE foams with temperature, compared with an EVA and a 

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EPDM in pLASTOTffiRS, SYNTHETIC - ETHYLENE-PROPYLENE-DIENE RUBBER] (Vol 8) -polycarbonate in [POLYCARBONATES] (Vol 19)... 

EPDM elastomers EPDM lonomers EPDM rubber... 

EPDM in pLASTOTffiRS, SYNTTiETIC - ETTiYLENE-PROPYLENE-DIENE RUBBER] pol 8)... 

NR, natural mbber CR, chloroprene SRs, synthetic mbbers IR, natural isoprene SBR, styrene—butadiene mbber BR, butadiene EPDM, ethylene—propjiene-diene EPM, ethylene—propylene polymer HR, isobutylene—isoprene NBR, nitrile—butadiene. 

An important newer use of fluorine is in the preparation of a polymer surface for adhesives (qv) or coatings (qv). In this apphcation the surfaces of a variety of polymers, eg, EPDM mbber, polyethylene—vinyl acetate foams, and mbber tine scrap, that are difficult or impossible to prepare by other methods are easily and quickly treated. Fluorine surface preparation, unlike wet-chemical surface treatment, does not generate large amounts of hazardous wastes and has been demonstrated to be much more effective than plasma or corona surface treatments. Figure 5 details the commercially available equipment for surface treating plastic components. Equipment to continuously treat fabrics, films, sheet foams, and other web materials is also available. 

A unique process for chemical stabili2ation of a ceUular elastomer upon extmsion has been shown for ethylene—propylene mbber the expanded mbber obtained by extmsion is exposed to high energy radiation to cross-link or vulcani2e the mbber and give dimensional stabUity (9). EPDM is also made continuously through extmsion and a combination of hot air and microwaves or radio frequency waves which both activate the blow and accelerate the cure. 

EPDM-Derived Ionomers. Another type of ionomer containing sulfonate, as opposed to carboxyl anions, has been obtained by sulfonating ethylene—propjlene—diene (EPDM) mbbers (59,60). Due to the strength of the cross-link, these polymers are not inherently melt-processible, but the addition of other metal salts such as zinc stearate introduces thermoplastic behavior (61,62). These interesting polymers are classified as thermoplastic elastomers (see ELASTOLffiRS,SYNTHETIC-THERMOPLASTICELASTOLffiRS). 

Occasionally polymers are used to increase the viscosity of oil-base and synthetic-base muds. The polymers for this use are typically sulfonated polystyrenes or ethylene—propylene terpolymers (EPDM) (54,55). Such polymers are usually used in conjunction with an organopbilic clay. 

Most elastomers that are used for nylon modification contain a small amount of maleic anhydride (0.3 to 2%). In the melt blending process, these elastomers react with the primary amine end groups in nylon, giving rise to nylon grafted elastomers. These grafts reduce the interfacial tension between the phases and provide steric stabili2ation for the dispersed mbber phase. Typically, thermally stable, saturated mbbers such as EPR, EPDM, and styrene—ethylene/butylene—styrene (SEBS) are used. 

The use of TAG as a curing agent continues to grow for polyolefins and olefin copolymer plastics and mbbers. Examples include polyethylene (109), chlorosulfonated polyethylene (110), polypropylene (111), ethylene—vinyl acetate (112), ethylene—propylene copolymer (113), acrylonitrile copolymers (114), and methylstyrene polymers (115). In ethylene—propylene copolymer mbber compositions. TAG has been used for injection molding of fenders (116). Unsaturated elastomers, such as EPDM, cross link with TAG by hydrogen abstraction and addition to double bonds in the presence of peroxyketal catalysts (117) (see Elastol rs, synthetic). 

Tires, natural mbber tubes, and butyl tubes are the main sources of scrap and reclaim (see Elastomers, synthetic-polyisoprene). Specialty reclaim materials are made from scrap siUcone, chloroprene (CR), nitrile— butadiene (NBR), and ethylene—propjlene—diene—terpolymer (EPDM) mbber scraps (see... 

At this point in the process, thermoplastic and chlorosulfonated polyethylene (CSPE) membranes are complete and are ready for packaging. In the case of ethylene—propylene—diene monomer (EPDM), the curing step occurs before the membrane is ready for packaging. The curing process is accomphshed by placing the membrane in a large vulcanizer where the material is heated under pressure to complete the cure. 

Polymeric Ma.teria.Is, The single-ply membranes are made from a wide variety of polymers. The following is a brief description of those polymers and their characteristics. There are three thermosetting-type elastomeric membranes as of this writing (1996) neoprene, CSPE, and EPDM. Neoprene is stiU used where oil resistance is needed. Eor instance. Hydrotech uses neoprene flashings, the base of which is hot-set in mbberized asphalt (see ElASTOL RS, SYNTHETIC-POLYCm.OROPRENE). 

EPDM is by far the most widely used material in the ballasted roofing system constmction. Because of EPDM s flexibiHty, very large sheets of up to 10,000 square feet (929 m ) can be deHvered to the job site in compact roUs that offer reduced labor on the roof in the seaming process. The typical EPDM sheet size used in ballasted systems is 12 by 30 m and 1.1 mm thick. EPDM is also widely used in both the fully adhered and mechanically fastened roofing systems. In these constmctions, both 1.1- and 1.5-mm thick material is used with widths from 2.1 to 15 m. A majority of the installations use nonreinforced sheet, although reinforced membrane can also be used in all of the system types. The majority of the reinforced sheets go into mechanically fastened systems. 

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