Abstract: An object of the present disclosure is to provide a polymer which is recyclable and capable of performing as equally well as a new product. Another object of the present disclosure is to provide a rubber composition containing said polymer, a method for manufacturing said rubber composition, and a rubber product containing said rubber composition. To achieve the objects, the present disclosure provides a complex polymer, comprising: a polymer main chain containing a conjugated diene unit and/or an olefin unit; and a functional group bonded to the polymer main chain, wherein: the functional group contains nitrogen atom and/or phosphorus atom therein and is complexed with a metal ion of an element of group 7-10 in the Periodic Table; and the bond dissociation energy for dissociation of the metal ion and the functional group is 200 kJ/mol or more.

Abstract: A method for cleaving a coordinate bond of a complex polymer that contains at least one polymer chain and a plurality of nitrogen- and/or phosphorus-containing functional groups which are bonded to the polymer chain and capable of forming coordinate bonds, wherein the coordinately-bondable nitrogen- and/or phosphorus-containing functional groups form a coordinate bond via a metal ion, characterized in that the method includes dissolving the complex polymer in a solvent containing a free ligand, to cleave the coordinate bond.

Abstract: Provided is a pneumatic tire that has excellent fuel efficiency and rubber strength and combines high load capacity and space saving. A pneumatic tire mounted on a vehicle, comprises: a tread configured to come into contact with a road surface; and a belt layer located on an inner side of the tread in a tire radial direction, wherein an outer diameter of the pneumatic tire is 350 mm or more and 600 mm or less, the following relationship: 0.78?RW/SW?0.88 is satisfied, where RW is a rim width of a rim wheel to be attached to the pneumatic tire and SW is a tire section width of the pneumatic tire, and a rubber composition that contains: a rubber component containing a diene-based rubber; and a mercaptocarboxylic acid compound is used in the pneumatic tire.

Abstract: A rubber composition contains a rubber component containing at least one selected from the group consisting of an isoprene rubber, a butadiene rubber, and a styrene-butadiene copolymer rubber, and a compound (1) represented by the following general formula (1). By using the rubber composition, it is possible to produce a rubber product having an excellent balance between a low strain hysteresis loss and a high strain hysteresis loss. [R1 and R2 in the general formula (1) each independently represent a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or an aryl group having 5 to 20 carbon atoms.

Abstract: Provided is a rubber composition that can improve the balance between the hysteresis loss of rubber at low strain and the hysteresis loss of rubber at high strain. The rubber composition comprises a rubber component, and at least one compound selected from the group consisting of the general formulas (1) and (2), HS—R—COOM??(1), and MOCO—R—(S)n—R—COOM??(2), where R is independently a linear or branched hydrocarbylene group having 8 or more carbon atoms in a linear portion connecting the sulfur atom and the COOM group; M is independently an atom selected from the group consisting of an alkali metal and an alkaline earth metal; and n is an integer from 2 to 8.