Epichlorhydrin rubber

Epichlorhydrin rubbers (CO, ECO and AECO)—Chapter 19 Propylene oxide mbber (GPO)—Chapter 19... 

This approach was used in the development of the epichlorhydrin rubbers which became commercially available around 1965 from Goodrich (Hydrin) and Hercules (Herclor). Both homopolymers of epichlorhydrin (Hydrin 100, Herclor H) and copolymers of epichlorhydrin with ethylene oxide (Hydrin 200, Herclor C) became available. (In 1986 Hercules sold their interest in these materials to Goodrich, who in turn later sold this to Nippon Zeon). 

Vulcanisation can be effected by diamines, polyamines and lead compounds such as lead oxides and basic lead phosphite. The homopolymer vulcanisate is similar to butyl rubber in such characteristics as low air permeability, low resilience, excellent ozone resistance, good heat resistance and good weathering resistance. In addition the polyepichlorohydrins have good flame resistance. The copolymers have more resilience and lower brittle points but air impermeability and oil resistance are not so good. The inclusion of allyl glycidyl ether in the polymerisation recipe produces a sulphur-curable elastomer primarily of interest because of its better resistance to sour gas than conventional epichlorhydrin rubbers. 

Epichlorhydrin rubbers, whilst being speciality materials, have a useful combination of properties which leads to their use in many applications such as gaskets, oil-field components, fuel pump diaphragms, oil seals, fuel and hydraulic hose and printing rollers. 

Epichlorhydrin rubbers are resistant to hydrocarbon fuels, to swelling in oils, and resistant to acids, bases, water, and aromatic hydrocarbons. However, they are susceptible to devulcanization in the presence of oxidized fuels such as sour gasoline. 

Epichlorhydrin rubber applications include seals and tubes in air-conditioning and fuel systems. 

Epichlorhydrin rubbers Two types are available, the homopolymer, polyepichlorhydrin (CO Rubber) with an average molecular weight of about 0 5 X 10 , and an equimolar copolymer of epichlorhydrin with ethylene oxide (ECO Rubber) with a molecular weight of about 2-3 X 10 ... 

Vulcanization of the epichlorhydrin rubbers is normally brought about by reaction of the chloromethyl group with diamines and polyamines or their derivatives such as hexamethylene diamine carbamate, with 2-mercaptobenzimidazoline, with lead oxide and lead phosphite, and with ammonium salts. The processes are analogous to those used with the polychloroprenes and with those acrylic rubbers containing a halogenated cure site. A sulphur-curable grade was announced in late 1977. 

Note that the results for epichlorhydrin rubber (ECO) are only for 70 h at 100°C and one would therefore not expect this polymer to be as good as nitrile in a direct comparison. 

There also exists a number of speciality rubbers whose applications are either very limited or well established. These include the chlorinated polyethylenes, the epichlorhydrin rubbers, the fluorosilicones, the ethylene-vinyl acetate rubbers, the polysulphides, the nitroso rubbers and the phosphonitrile fluoroelastomers. Changes in the uses of these materials are likely to have very little impact on the usage of general purpose and major special purpose rubbers. They have also been the subject of a recent review. ... 

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