Ethylene-propylene copolymer rubber

Cross-Linking of Ethylene-Propylene Copolymer Rubber with Dicumyl Peroxide-Maleic Anhydride... 

The crosslinking of ethylene-propylene copolymer rubber (EPR) in the presence of organic peroxides has been investigated by Natta and/or his coworkers (1-3) and others (4,5). Co-agents such as sulfur (3,4) and unsaturated monomers (6), including maleic anhydride (MAH)(3,7) have been utilized in an effort to increase the crosslinking efficiency in the EPR-peroxide system. 

GAYLORD ETAL. Ethylene-Propylene Copolymer Rubber... 

Impact-modified polypropylenes are produced by combining the homopolymer with an ethylene-propylene copolymer rubber. Ziegler-Natta processes yield such products in cascaded reactors. The first reactor in the sequence produces a rigid polymer with a high propylene content and feeds the second reactor, where the ethylene-propylene elastomer is polymerized in intimate mixture with the first material. 

The same technique can be used to dye a material that is otherwise difficult to dye. An ethylene-propylene copolymer rubber was reacted first with maleic anhydride, then with an aromatic amine dye in an extruder to produce a dyed rubber.81 Dye sites can also be inserted into polyolefins by grafting them with dimethylaminoethyl methacrylate, using azo or peroxide catalysts in an extruder.82 jV-Vinylimidazole has been grafted to polyethylene in an extruder with the help of dicumylperoxide.83 The product was mixed with an acrylic acid-modified polypropylene and used to compatibilize polyethylene and polypropylene. This could be helpful in the recycling of mixed polyolefins from municipal solid waste. Recycling of cross-linked (thermoset) polymers is more of a problem because they cannot be remelted in an extruder. However, they can be if... 

Gardner,I.J., Cozewith,C., Ver Strate,G. Infrared determination of composition of ethylene-propylene copolymers. Rubber Chem. Technol. 44, 1015-1024 (1971). 

Figure 6.29. Infrared curves of (1) polypropylene-linear polyethylene blend, (2) ethylene-propylene copolymer rubber, (3) propylene-ethylene polyallomer. (Hagenmeyer and Edwards, 1966.)...

Polyamide (PA)/maleic-anhydride (MA)-functionalised polyolefin (PO) blends provide a compatibility strategy consisting of maleation of the PO phase followed by a reactive processing favouring copolymer formation by imidisation between the anhydride and amine chain ends. The PO is most often ethylene-propylene copolymer rubber, PP or PE, and the PA is commonly PA6 or PA6,6 [49-58]. 

The methods of DSC and IR spectroscopy were used to study various blends of poly(3-hydroxybu-tyrate) with ethylene-propylene copolymer rubber (EP). When the weight fractions of the initial pol5miers are equal, a phase inversion takes place as the blends are enriched with EP, the degree of crystallinity of poly(3-hydroxybutyrate) decreases. In blends, the degradation of poly(3-hydroxybutyrate) begins at a lower temperature compared to the pure polymer and the thermooxidative activity of the ethylene-propylene copolymer in the blend decreases in comparison with the pure copolymer. 

The Tg of an ethylene-propylene copolymer rubber is — 50 C. When the EPR is blended with PA6.6, the fracture resistance of the blend in slow bending tests on notched bars, first shows a significant increase at — 50 C. In this test, the time taken to reach peak load is Is. Toughening occurs when the rubber particles have time to stress relax and to initiate plastic deformation in the PA6.6 matrix. Calculate the minimum temperature required to achieve toughening in the Charpy impact test. Use the WLF equation,... 

Like the ethylene-propylene copolymer rubbers these rubbers are saturated and exhibit good oxygen, ozone and heat ageing resistance whilst those based on methyl acrylate also have some claim to oil resistance. 

In the early history of polypropylene technology, blends with ethylene propylene copolymer were introduced for toughening polypropylene. Subsequently block copolymers of polypropylene with random ethylene propylene copolymer rubber were produced in the polymerization reaction. Dynamic vulcanization of ethylene propylene terpolymer in blends with polypropylene together with hydrocarbon oils was a third technology. The first TPO was elastomer (ethylene)-modified propylene (EP polymer) marketed to overcome polypropylene s weakness that cold temperature negatively impacts resistance. 

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