a fluororubber composition includes (a) a peroxide-crosslinkable fluorine-containing elastomer; (b) a spherical particle of a silica/cured melamine resin composite; (c) carbon black; (d) an organic peroxide as a crosslinking agent; and (e) a co-crosslinking agent.

The two-part composition includes a first part and a second part. The first part includes a vinyl-substituted polysiloxane, a hydrosilylation catalyst, expandable graphite comprising moisture, and first polymeric microspheres having been at least partially coated with inorganic filler. The second part includes a second vinyl-substituted polysiloxane, a hydrosilyl-substituted polysiloxane, and second polymeric microspheres having been at least partially coated with flame-retardant inorganic filler. The two-part composition is useful, for example, for curing into a sealant and making an assembly. The assembly has a first substrate and a second substrate with a cured product of the two-part composition in contact with the first substrate and the second substrate. Methods of making a sealant and an assembly are also described.

A gasket includes an elastic part containing a rubber having a dynamic-to-static ratio, Kd/Kst, of 2.5 or lower, wherein the dynamic-to-static ratio, Kd/Kst, is a ratio between a dynamic spring constant, Kd, and a static spring constant, Kst. The dynamic spring constant, Kd, represents a constant as measured under conditions of 23±2° C., 100 Hz, and a strain amplitude of 0.1% according to JIS K6394:2007, and the static spring constant, Kst, represents a constant as measured under conditions of 23±2° C. and a strain amplitude of 0.1% according to JIS K6394:2007.

A gasket includes an elastic part containing a rubber having a dynamic spring constant of 1.5 g/μm or lower as measured under conditions of 23±2° C., 100 Hz, and a strain amplitude of 0.1% according to JIS K6394:2007.

A sealing body for dynamic applications has a Shore A hardness of between 60-100, comprising an elastomer material and carbon nanotubes distributed in the elastomer material in an amount of between 0.1-20 phr, with respect to the total amount of elastomer material.

A spherical annular seal member 38 is used in an exhaust pipe joint and includes a spherical annular base member 36 defined by a cylindrical inner surface 32, a partially convex spherical surface 33, large- and small-diameter side annular end faces 34 and 35 of the partially convex spherical surface 33, and an outer layer 37 formed integrally on the partially convex spherical surface 33 of the spherical annular base member 36. The spherical annular base member 36 includes a reinforcing member made from a metal wire net 5 and a heat-resistant material containing expanded graphite filling meshes of the metal wire net 5 of this reinforcing member and compressed in such a manner as to be formed integrally with this reinforcing member in mixed form. In the outer layer 37, the reinforcing member, the heat-resistant material, and the solid lubricant are integrated in mixed form.

Provided is a rubber composition for sealing material which contains 100 parts by mass of a rubber component, 50 to 140 parts by mass of silica, 1 to 20 parts by mass of a silane coupling agent, and 15 to 35 parts by mass of carbon black. The rubber component is preferably an ethylene-propylene-diene rubber.

A gasket material comprising a crosslinked fluororubber layer having a micro-hardness of 5 to 25 formed on a metal plate using a fluororubber composition comprising 30 to 70 parts by weight of carbon black having a CTAB specific surface area of 3 to 34 m.sup.2/g, and 5 to 15 parts by weight of hydrated amorphous silicon dioxide having a BET specific surface area of 35 to 220 m.sup.2/g, based on 100 parts by weight of fluororubber, wherein the total amount of carbon black and hydrated amorphous silicon dioxide is 80 parts by weight or less.

Provided are a perfluoroelastomer composition which contains 100 parts by weight of a perfluoroelastomer containing a constituent unit derived from a nitrile group-containing monomer, and 0.01 to 5 parts by weight of ketjen black; and a sealing material including a crosslinked product of the perfluoroelastomer composition.

A composition including a perfluoroelastomer, carbon black in an amount of 55 to 75 parts by weight per 100 parts by weight of the perfluoroelastomer, and a crosslinking agent represented by the following formula (1): wherein in the formula (1), A is a single bond, —O—, an alkylene group, or a fluoroalkylene group; R.sup.1, R.sup.2, and R.sup.3 are independently a hydrogen atom, a fluorine atom, an alkyl group, or a fluoroalkyl group; and provided that at least one of R.sup.1, R.sup.2, and R.sup.3 is a fluorine atom or a fluoroalkyl group.

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