Abstract: A ring-opened copolymer including structural units derived from a norbornene compound having a specific structure and structural units derived from a monocyclic olefin, wherein the proportion of the structural units derived from a norbornene compound is 25 to 90 wt % and the proportion of the structural units derived from a monocyclic olefin is 10 to 75 wt % relative to the total repeating structural units in the ring-opened copolymer, the weight average molecular weight of the ring-opened copolymer is 100,000 to 1,000,000, and the cis/trans ratio of the ring-opened copolymer is 0/100 to 50/50.

Abstract: A ring-opened copolymer composition has a ring-opened copolymer containing structural unit derived from a norbornene compound represented by general formula (1) below and structural unit derived from a monocyclic olefin, wherein a content of a norbornene compound represented by general formula (1) is 1 ppm by weight or more and 1000 ppm by weight or less based on the ring-opened copolymer, wherein R1 to R4 are each a hydrogen atom, a hydrocarbon group having 1 to 20 carbon atoms, or a substituent containing a halogen atom, a silicon atom, an oxygen atom or a nitrogen atom, and R2 and R3 may be bonded to each other to form a ring, and “m” is 0 or 1.

Abstract: A crosslinkable composition containing: a liquid monocyclic olefin ring-opened polymer (A) having a reactive group at a polymer chain end thereof and a weight-average molecular weight (Mw) of 1,000 to 50,000; and a crosslinkable compound (B) having, in the molecule, two or more functional groups reactive with the reactive group at the polymer chain end of the monocyclic olefin ring-opened polymer (A).

Abstract: A liquid cyclopentene ring-opened copolymer includes a monomer unit derived from cyclopentene and a monomer unit derived from a norbornene compound, the monomer unit derived from cyclopentene being present in an amount of 60 to 95 wt %, the liquid cyclopentene ring-opened copolymer having a hydroxyl group-terminated copolymer chain and having a melt viscosity at 25° C. of less than 500 Pa·s, which is measured using a B-type viscometer.

Abstract: A rubber composition that contains 0.1 to 50 parts by weight of an organic peroxide with respect to 100 parts by weight of a cyclopentene ring-opening polymer.

Abstract: A cyclopentene ring-opening copolymer having a branch structure contains a structure in which at least four cyclopentene ring-opening polymer chains are linked via a branch-structural unit. At least part of the cyclopentene ring-opening polymer chains is terminally modified.

Abstract: A rubber composition containing: a solid rubber (A) having a weight-average molecular weight (Mw) of 100,000 or more; and a liquid monocyclic olefin ring-opened polymer (B) having a weight-average molecular weight (Mw) of 1,000 to 50,000, wherein a proportion of the liquid monocyclic olefin ring-opened polymer (B) is 1 to 100 parts by weight per 100 parts by weight of the solid rubber (A).

Abstract: A crosslinked rubber is produced by crosslinking a polymer composition containing 100 parts by weight of a rubber component containing a cyclopentene ring-opening polymer and 20 to 200 parts by weight of carbon black, wherein, when the crosslinked rubber is subjected to an ozone treatment in which the rubber is maintained at 40° C. and an ozone concentration of 50 pphm for 144 hours under a 20% tensile strain, the crosslinked rubber shows a rate of change in tensile strength before and after ozone treatment of within ±70%.

Abstract: A cycloolefin ring-opened copolymer including a structural unit derived from a monocyclic olefin and a structural unit derived from a norbornene compound, wherein a difference (?Tg) between an extrapolated glass transition ending temperature (Teg) and an extrapolated glass transition initiating temperature (Tig) obtained according to JIS K7121 is 30° C. or less, and a weight average molecular weight (Mw) is 50,000 to 1,000,000 is provided.

Abstract: A ring-opened copolymer composition comprising a ring-opened copolymer containing structural unit derived from a norbornene compound represented by general formula (1) below and structural unit derived from a monocyclic olefin, wherein a content of a norbornene compound represented by general formula (1) is 1 ppm by weight or more and 1000 ppm by weight or less based on the ring-opened copolymer is provided. wherein R1 to R4 are each a hydrogen atom, a hydrocarbon group having 1 to 20 carbon atoms, or a substituent containing a halogen atom, a silicon atom, an oxygen atom or a nitrogen atom, and R2 and R3 may be bonded to each other to form a ring, and “m” is 0 or 1.

Abstract: A ring-opened copolymer including structural units derived from a norbornene compound having a specific structure and structural units derived from a monocyclic olefin, wherein the proportion of the structural units derived from a norbornene compound is 25 to 90 wt % and the proportion of the structural units derived from a monocyclic olefin is 10 to 75 wt % relative to the total repeating structural units in the ring-opened copolymer, the weight average molecular weight of the ring-opened copolymer is 100,000 to 1,000,000, and the cis/trans ratio of the ring-opened copolymer is 0/100 to 50/50.

Abstract: A crosslinked rubber is a member for use in an environment at ?10° C. or less produced by crosslinking a polymer composition containing 20 to 200 parts by weight of carbon black with respect to 100 parts by weight of a rubber component containing a monocyclic olefin ring-opening polymer having a proportion of cis bond of a structural unit derived from a monocyclic olefin of 45 to 95%.

Abstract: A cyclopentene ring-opening copolymer having a branch structure contains a structure in which at least four cyclopentene ring-opening polymer chains are linked via a branch-structural unit. At least part of the cyclopentene ring-opening polymer chains is terminally modified.

Abstract: A liquid cyclopentene ring-opened copolymer includes a monomer unit derived from cyclopentene and a monomer unit derived from a norbornene compound, the monomer unit derived from cyclopentene being present in an amount of 60 to 95 wt %, the liquid cyclopentene ring-opened copolymer having a hydroxyl group-terminated copolymer chain and having a melt viscosity at 25° C. of less than 500 Pa·s, which is measured using a B-type viscometer.

Abstract: A crosslinkable composition containing: a liquid monocyclic olefin ring-opened polymer (A) having a reactive group at a polymer chain end thereof and a weight-average molecular weight (Mw) of 1,000 to 50,000; and a crosslinkable compound (B) having, in the molecule, two or more functional groups reactive with the reactive group at the polymer chain end of the monocyclic olefin ring-opened polymer (A).

Abstract: A rubber composition that contains 0.1 to 50 parts by weight of an organic peroxide with respect to 100 parts by weight of a cyclopentene ring-opening polymer.

Abstract: A crosslinked rubber is a member for use in an environment at ?10° C. or less produced by crosslinking a polymer composition containing 20 to 200 parts by weight of carbon black with respect to 100 parts by weight of a rubber component containing a monocyclic olefin ring-opening polymer having a proportion of cis bond of a structural unit derived from a monocyclic olefin of 45 to 95%.

Abstract: [Problem] To provide a cyclopentene ring-opening copolymer used in a rubber composition for tires having excellent wet grip performance and low heat buildup; and a method for producing the cyclopentene ring-opening copolymer. To further provide a rubber composition obtained by using the cyclopentene ring-opening copolymer. [Solution] This cyclopentene ring-opening copolymer comprises cyclopentene and a cyclic olefin containing an aromatic ring; the content of the aromatic ring with respect to the total weight of the copolymer is 10 to 40 wt %; and the weight average molecular weight (Mw) is 200,000 to 1,000,000. The cyclopentene ring-opening copolymer alternatively comprises cyclopentene and a norbornene compound; the weight ratio of cyclopentene-derived structural units to all repeating structural units in the copolymer is 40 to 90 wt %, and the weight ratio of norbornene compound-derived structural units is 10 to 60 wt %; and the weight average molecular weight (Mw) is 200,000 to 1,000,000.

Abstract: A cyclopentene ring-opening polymer having, at a polymer chain end, a structure where a polymer chain and a group containing an alkoxysilyl group are bonded through —NH— and having a weight average molecular weight of 100,000 to 1,000,000, wherein the structure is a structure represented by the following general formula (1): pCP—Y1-NH—Y2-Si(OR1)a(R2)3-a??(1) where, in the general formula (1), pCP represents a cyclopentene ring-opening polymer chain, Y1 represents a bivalent hydrocarbon group having 1 to 20 carbon atoms, each of R1 and R2 represents a hydrocarbon group having 1 to 20 carbon atoms, Y2 represents a bivalent hydrocarbon group having 1 to 20 carbon atoms in which —NH— may be interposed, and “a” is an integer of 1 to 3.

Abstract: A rubber composition containing: a solid rubber (A) having a weight-average molecular weight (Mw) of 100,000 or more; and a liquid monocyclic olefin ring-opened polymer (B) having a weight-average molecular weight (Mw) of 1,000 to 50,000, wherein a proportion of the liquid monocyclic olefin ring-opened polymer (B) is 1 to 100 parts by weight per 100 parts by weight of the solid rubber (A).