Ethylene-propylene-diene rubbers

Copolymers of ethylene and propylene (EPM) and terpolymers of ethylene, propylene, and a diene (EPDM) as manufactured today are mbbers based on the early work of G. Natta and co-workers (1). A genetic formula for EPM and EPDM may be given as follows, where ra = (- GO mol%), 

EPM can be vulcanised radically by means of peroxides. A small amount of built-in third diene monomer in EPDM permits conventional vulcanisa tion with sulfur at the pendent sites of unsaturation. 

Even though EPM and EPDM mbbers have been commercially available for more than 30 years, the technology concerning these products, both their production and their appHcations, is stiU very much under development. 

Although the mbbery properties of ethylene—propylene copolymers are exhibited over a broad range of compositions, weight percentages of commercial products generally range from 50 50 to 75 25 ethylene propylene. 

The most commonly used third monomer is 5-ethyHdene-2-norbomene [16219-75-3] or ENB  

This is a nonpolar rubber with very little unsamration. Nanoclays as well as nanotubes have been used to prepare nanocomposites of ethylene-propylene-diene monomer (EPDM) rubber. The work mostly covers the preparation and characterization of these nanocomposites. Different processing conditions, morphology, and mechanical properties have been smdied [61-64]. Acharya et al. [61] have prepared and characterized the EPDM-based organo-nanoclay composites by X-ray diffracto-gram (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy 

Source Acharya, H., Pramanik, M., Srivastava, S.K., and Bhowmick, A.K., J. Appl. Polym. Sci., 93, 2429, 2004. Courtesy of Wiley InterScience. 

The results suggest that the thermal stability improves with higher loading till 6 phr of nanoclay and this improvement is attributed to the barrier effect of the exfoliated and the intercalated nanoclay particles. 

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Ethylene-propylene-diene rubber is polymerized from 60 parts ethylene, 40 parts propylene, and a small amount of nonconjugated diene. The nonconjugated diene permits sulfur vulcanization of the polymer instead of using peroxide. 

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

ELASTOTffiRS,SYNTHETIC - ETHYLENE-PROPYLENE-DIENE RUBBER] (Vol 8)... 

ELASTOPffiRS,SYNTHETic-POLYcm.OROPRENE Elastop rs, SYNTHETIC-ETHYLENE-PROPYLENE-DIENE RUBBER). Tires, hoses, belts, molded and extmded goods, and asphalt products consume ca 80% of the reclaimed mbber manufactured. Typical properties of reclaimed mbbers are shown in Table 5. 

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. 

Ethylene—Propylene (Diene) Rubber. The age-resistant elastomers are based on polymer chains having a very low unsaturation, sufficient for sulfur vulcanization but low enough to reduce oxidative degradation. EPDM can be depicted by the following chain stmcture ... 

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