A triblock polymer of formula B-A-B is provided. According to the formula, the symbol A represents a central block which is a statistical copolymer comprising units of a 1,3-diene and more than 50 mol % of ethylene units. The symbols B each represent an end block which is a polyethylene with a melting point of greater than 90 C. and a number-average molar mass of greater than or equal to 2000 g/mol and less than or equal to 10 000 g/mol. The polymer has improved rheological properties relative to a statistical copolymer based on ethylene and 1,3-diene of the same microstructure without changing its mechanical and dynamic or thermal properties.

The present invention relates to a method for preparing a polyolefin block copolymer, the method comprising: a first step of coordination polymerization of an olefin monomer with a transition metal catalyst in the presence of organozinc; and a second step of continuously adding a diacyl peroxide compound to perform polymerization, and to a polyolefin block copolymer prepared therefrom.

A tire (1) comprises a tread (3), a crown with a crown reinforcement (2), two sidewalls (5), two beads (4), a carcass reinforcement (6) anchored to the two beads (4) and extending from one sidewall (5) to the other, the tread comprising (a) an elastomeric matrix which comprises predominantly one or more thermoplastic elastomers comprising at least one elastomer block and at least one thermoplastic block, and (b) a crosslinking system based on one or more peroxides. The invention also relates to a process for preparing the retire.

An object of the present invention is to provide expanded beads capable of producing an expanded beads molded article that is excellent in in-mold moldability and is excellent with good balance in lightweight property, flexibility, repulsion, restorability, and tensile characteristics, and an expanded beads molded article using the expanded beads. The expanded beads molded article of the present invention is produced by subjecting the crosslinked expanded beads of the present invention, to in-mold molding. The expanded beads molded article of the present invention may have an apparent density of from 40 to 150 g/L.

A tire has an outer sidewall, said outer sidewall comprising at least one composition comprising an elastomeric matrix which predominantly comprises by weight one or more thermoplastic elastomers comprising at least one elastomer block and at least one thermoplastic block, the elastomer block(s) being saturated.

A semicrystalline multiblock copolymer includes alternating blocks of semicrystalline isotactic polypropylene (iPP) and semicrystalline polyethylene (PE), having a block arrangement according to formula (I):

(iPP.sub.w).sub.p(PE.sub.x)(iPP.sub.y).sub.m(PE.sub.z).sub.n (I),

wherein p is 0 or 1; m is 0 or 1; n is 0 or 1; the sum of p, m, and n is 1, 2, or 3; and the sum of w, x, y, and z is greater than or equal to 40 kg/mol, with the provisos that: when m and n are 0, the sum of w and x is greater than or equal to 140 kg/mol; and when p and n are 0, the sum of y and x is greater than or equal to 140 kg/mol. Related compositions and methods are also provided.

A thermoplastic vulcanizate composition includes (a) a crystalline thermoplastic polyolefin comprising alpha-olefin monomers having from 2 to 5 carbon atoms, (b) a rubber block interpolymer comprising a first block and a second block having differing chemical or physical properties from the first block, the first block is derived from ethylene, a first alpha-olefin monomer having from 3 to 10 carbon atoms, and a first diene monomer having from 2 to 25 carbon atoms, the second block is derived from ethylene, a second alpha-olefin monomer having from 3 to 10 carbon atoms, and optionally a second diene monomer having from 2 to 25 carbon atoms, and an amount of the block interpolymer in the composition being greater than an amount of the thermoplastic polyolefin in the composition, and (c) a curative system.

An object of the present invention is to provide expanded beads capable of producing an expanded beads molded article that is excellent in in-mold moldability and is excellent with good balance in lightweight property, flexibility, repulsion, restorability, and tensile characteristics, and an expanded beads molded article using the expanded beads. For achieving the object, the present invention provides crosslinked expanded beads produced by crosslinking and expanding particles containing a multi-block copolymer containing a polyethylene block and an ethylene--olefin copolymer block, the multi-block copolymer having a melt flow rate of from 2 to 10 g/10 min at 190 C. and a load of 2.16 kg, and a Shore A hardness of from 65 to 90 measured according to ASTM D2240, the crosslinked expanded beads having a gel fraction of from 30 to 60% by a hot xylene extraction method. The expanded beads molded article of the present invention is produced by subjecting the crosslinked expanded beads of the present invention, to in-mold molding. The expanded beads molded article of the present invention may have an apparent density of from 40 to 150 g/L.

A thermoplastic vulcanizate composition includes (a) a crystalline thermoplastic polyolefin comprising alpha-olefin monomers having from 2 to 5 carbon atoms, (b) a rubber block interpolymer comprising a first block and a second block having differing chemical or physical properties from the first block, the first block is derived from ethylene, a first alpha-olefin monomer having from 3 to 10 carbon atoms, and a first diene monomer having from 2 to 25 carbon atoms, the second block is derived from ethylene, a second alpha-olefin monomer having from 3 to 10 carbon atoms, and optionally a second diene monomer having from 2 to 25 carbon atoms, and an amount of the block interpolymer in the composition being greater than an amount of the thermoplastic polyolefin in the composition, and (c) a curative system.

A semicrystalline multiblock copolymer includes alternating blocks of semicrystalline isotactic polypropylene (iPP) and semicrystalline polyethylene (PE), having a block arrangement according to formula (I):
(iPP.sub.w).sub.p(PE.sub.x)(iPP.sub.y).sub.m(PE.sub.z).sub.n (I),
wherein p is 0 or 1; m is 0 or 1; n is 0 or 1; the sum of p, m, and n is 1, 2, or 3; and the sum of w, x, y, and z is greater than or equal to 40 kg/mol, with the provisos that: when m and n are 0, the sum of w and x is greater than or equal to 140 kg/mol; and when p and n are 0, the sum of y and x is greater than or equal to 140 kg/mol. Related compositions and methods are also provided.