A rubber composition comprising 1 to 10 parts by weight of an organic peroxide crosslinking agent having a one-hour half-life temperature of 110 to 130 C., based on 100 parts by weight of an ethylene-butene-non-conjugated diene copolymer. The ethylene-butene-non-conjugated diene copolymer can be used by being blended with EPDM in an amount of 50 wt % or less in the total amount of the ethylene-butene-non-conjugated diene copolymer and EPDM. A sealing material for fuel cell separators comprising a crosslinked molded article of the rubber composition has, in addition to functions required as a sealing material for separators, improved low temperature sealing properties.

A rubber composition comprising 1 to 10 parts by weight of an organic peroxide crosslinking agent having a one-hour half-life temperature of 110 to 130 C., based on 100 parts by weight of an ethylene-butene-non-conjugated diene copolymer. The ethylene-butene-non-conjugated diene copolymer can be used by being blended with EPDM in an amount of 50 wt % or less in the total amount of the ethylene-butene-non-conjugated diene copolymer and EPDM. A sealing material for fuel cell separators comprising a crosslinked molded article of the rubber composition has, in addition to functions required as a sealing material for separators, improved low temperature sealing properties.

In at least one embodiment, a process of forming a polymer includes supplying a feed having one or more olefin monomers and a solvent; contacting the feed with a catalyst to form a reaction mixture; treating the reaction mixture in a first separator to form a first polymer-rich mixture; introducing the first polymer-rich mixture into a second separator; introducing a volatile component and/or inert component into the first separator, the second separator and/or a line between the first separator and the second separator; treating the first polymer-rich mixture to form a second polymer-rich mixture; and devolatilizing the second polymer-rich mixture to obtain the polymer.

In at least one embodiment, a process of forming a polymer includes supplying a feed having one or more olefin monomers and a solvent; contacting the feed with a catalyst to form a reaction mixture; treating the reaction mixture in a first separator to form a first polymer-rich mixture; introducing the first polymer-rich mixture into a second separator; introducing a volatile component and/or inert component into the first separator, the second separator and/or a line between the first separator and the second separator; treating the first polymer-rich mixture to form a second polymer-rich mixture; and devolatilizing the second polymer-rich mixture to obtain the polymer.

A rubber composition for a torsional damper has (A) a minimum value of tan at 30 C. to 120 C. of 0.140 or more, (B) a ratio of tan at 30 C. to tan at 60 C. of 3.5 or less, and (C) a ratio of E at 30 C. to E at 60 C. of 21 or less.

A rubber composition for a torsional damper has (A) a minimum value of tan at 30 C. to 120 C. of 0.140 or more, (B) a ratio of tan at 30 C. to tan at 60 C. of 3.5 or less, and (C) a ratio of E at 30 C. to E at 60 C. of 21 or less.

A rubber composition based at least on an elastomer matrix, on a reinforcing filler and on a vulcanization system is provided. The elastomer matrix comprises a highly saturated elastomer and from 0 to less than 30 phr of natural rubber. The highly saturated diene elastomer contains 1,3-diene units and more than 50 mol % of ethylene units. The vulcanization system comprises a dithiosulfate salt of formula MO.sub.3SS-A-SSO.sub.3M in which the symbol A represents an alkanediyl group or a group comprising two or more alkanediyl units, which units are connected in pairs via an oxygen or sulfur atom, via a group of formula SO.sub.2, NH, NH.sub.2.sup.+, N(C.sub.1-C.sub.16 alkyl)- or COO, or via an arylene or cycloalkylene group, and the symbol M represents a metal atom. The invention makes it possible to achieve an improved compromise between bubble formation in the rubber composition on exiting from the curing presses and its hysteresis.

A rubber composition based at least on an elastomer matrix, on a reinforcing filler and on a vulcanization system is provided. The elastomer matrix comprises a highly saturated elastomer and from 0 to less than 30 phr of natural rubber. The highly saturated diene elastomer contains 1,3-diene units and more than 50 mol % of ethylene units. The vulcanization system comprises a dithiosulfate salt of formula MO.sub.3SS-A-SSO.sub.3M in which the symbol A represents an alkanediyl group or a group comprising two or more alkanediyl units, which units are connected in pairs via an oxygen or sulfur atom, via a group of formula SO.sub.2, NH, NH.sub.2.sup.+, N(C.sub.1-C.sub.16 alkyl)- or COO, or via an arylene or cycloalkylene group, and the symbol M represents a metal atom. The invention makes it possible to achieve an improved compromise between bubble formation in the rubber composition on exiting from the curing presses and its hysteresis.

A method comprising introducing a polymerization feed comprising an -olefin, a diluent, and a diene to a polymerization system, under polymerization conditions, whereby a polymer product is produced, wherein the diene is present at a level in the range of from about 1 ppm to about 1000 ppm based on the diluent.

A method comprising introducing a polymerization feed comprising an -olefin, a diluent, and a diene to a polymerization system, under polymerization conditions, whereby a polymer product is produced, wherein the diene is present at a level in the range of from about 1 ppm to about 1000 ppm based on the diluent.