A styrenic block copolymer having one or more polymer blocks A and one or more polymer blocks B is disclosed, where “A” is a poly(vinylaromatic) block having a molecular weight of greater than 5 kg/mol. The “B” block has a molecular weight of more than 15 kg/mol, and comprises polymerized 1,3-diene units and vinylaromatic units, wherein the polymerized vinylaromatic units represent 5-40 wt. % of the overall weight of the block “B”. The polymerized 1,3-diene units comprise more than 80 wt. % of polymerized isoprene units in which 45-80 mol % are 1,4-isoprene addition units. The blocks “A” and “B” represent from >5 to <40 wt. %, and >33 to <95 wt. %, respectively, relative to the overall weight of the block copolymer. The polymers have physical properties that make them valuable, e.g., as vibration damping materials.

A crosslinkable and foamable composition is provided, which comprises a hydrogenated styrenic diblock copolymer, a free radical initiator and a foaming agent, wherein the hydrogenated styrenic diblock copolymer comprises: a first block comprising a conjugated diene monomer unit; and a second block comprising a styrene unit, wherein the hydrogenated styrenic diblock copolymer comprises 10 to 60 wt % of the styrene unit, 50 mol % or more of the conjugated diene monomer unit is hydrogenated, and the hydrogenated styrenic diblock copolymer has a weight average molecular weight of 30000 to 200000. In addition, a foam obtained by crosslinking and foaming the aforesaid crosslinkable and foamable composition is also provided.

A block copolymer including a polymer block (A) containing more than 70 mol % of a unit derived from an aromatic vinyl compound, and a polymer block (B) containing 30 mol % or more of a unit derived from a conjugated diene compound is provided. The block copolymer satisfies the conditions: (1): a content of the polymer block (A) in the block copolymer is 1 to 70% by mass; (2): a maximum width of a series of temperature regions where tan δ measured in accordance with JIS K7244-10 (2005), under conditions including a strain amount of 0.1%, a frequency of 1 a measurement temperature of −70 to 100° C., and a temperature rise rate of 3° C./min, is 1.0 or more is less than 16° C.; (3): a temperature at a peak position of tan δ in the condition (2) is 0° C. to +50° C.; and (4): a mobility parameter M indicating a mobility of the polymer block (B) is 0.01 to 0.25 sec.

A block copolymer including a polymer block (A) containing more than 70 mol % of a unit derived from an aromatic vinyl compound, and a polymer block (B) containing 30 mol % or more of a unit derived from a conjugated diene compound is provided. The block copolymer satisfies the conditions: (1): a content of the polymer block (A) in the block copolymer is 1 to 70% by mass; (2): a maximum width of a series of temperature regions where tan δ measured in accordance with JIS K7244-10 (2005), under conditions including a strain amount of 0.1%, a frequency of 1 a measurement temperature of −70 to 100° C., and a temperature rise rate of 3° C./min, is 1.0 or more is less than 16° C.; (3): a temperature at a peak position of tan δ in the condition (2) is 0° C. to +50° C.; and (4): a mobility parameter M indicating a mobility of the polymer block (B) is 0.01 to 0.25 sec.

To provide a waterproof sheet for civil engineering, having sufficient strength and elongation even at a low temperature of about −10° C. and having excellent adhesiveness to a structure such as a tunnel. Disclosed is a waterproof sheet for civil engineering, which has a layer (A) including a composition containing an ethylene-vinyl acetate copolymer (a1) and a thermoplastic resin (a2) other than the ethylene-vinyl acetate copolymer (a1), and a silica-containing layer containing silica, wherein the content of the ethylene-vinyl acetate copolymer (a1) in the composition is 30 to 95% by mass, the content of the thermoplastic resin (a2) is 5 to 70% by mass, and the absolute value of the difference between the SP value of the ethylene-vinyl acetate copolymer (a1) and the SP value of the thermoplastic resin (a2) is less than 0.70 (cal/cm.sup.3).sup.1/2.

To provide a waterproof sheet for civil engineering, having sufficient strength and elongation even at a low temperature of about −10° C. and having excellent adhesiveness to a structure such as a tunnel. Disclosed is a waterproof sheet for civil engineering, which has a layer (A) including a composition containing an ethylene-vinyl acetate copolymer (a1) and a thermoplastic resin (a2) other than the ethylene-vinyl acetate copolymer (a1), and a silica-containing layer containing silica, wherein the content of the ethylene-vinyl acetate copolymer (a1) in the composition is 30 to 95% by mass, the content of the thermoplastic resin (a2) is 5 to 70% by mass, and the absolute value of the difference between the SP value of the ethylene-vinyl acetate copolymer (a1) and the SP value of the thermoplastic resin (a2) is less than 0.70 (cal/cm.sup.3).sup.1/2.

A styrene-isoprene/butadiene diblock copolymer contains a polystyrene block and a polyisoprene/butadiene block. Based on 100 wt % of the styrene-isoprene/butadiene diblock copolymer, the polystyrene block is 20-45 wt %, and the polyisoprene/butadiene block is 55-80 wt %. The polyisoprene/butadiene block has a polyisoprene unit and a polybutadiene unit. The weight ratio of the polyisoprene unit to the polybutadiene unit is 8:2 to 2:8.

A styrene-isoprene/butadiene diblock copolymer contains a polystyrene block and a polyisoprene/butadiene block. Based on 100 wt % of the styrene-isoprene/butadiene diblock copolymer, the polystyrene block is 20-45 wt %, and the polyisoprene/butadiene block is 55-80 wt %. The polyisoprene/butadiene block has a polyisoprene unit and a polybutadiene unit. The weight ratio of the polyisoprene unit to the polybutadiene unit is 8:2 to 2:8.

Provided is a thermoplastic elastomer composition and the like which can have improved vibration-damping properties while retaining properties inherent in a polyester-based thermoplastic elastomer. The thermoplastic elastomer composition contains a polyester-based thermoplastic elastomer (A) and a hydrogenated aromatic vinyl compound-based elastomer (B) having a glass transition temperature Tg of −10 to 40° C., wherein the hydrogenated aromatic vinyl compound-based elastomer (B) is a hydrogenate of a block copolymer containing a polymer block (a) having a structural unit derived from an aromatic vinyl compound and a polymer block (b) having a structural unit derived from a conjugated diene compound, and the ratio by mass of the polyester-based thermoplastic elastomer (A) to the hydrogenated aromatic vinyl compound-based elastomer (B), (A/B) is 99/1 to 1/99.

Provided is a thermoplastic elastomer composition and the like which can have improved vibration-damping properties while retaining properties inherent in a polyester-based thermoplastic elastomer. The thermoplastic elastomer composition contains a polyester-based thermoplastic elastomer (A) and a hydrogenated aromatic vinyl compound-based elastomer (B) having a glass transition temperature Tg of −10 to 40° C., wherein the hydrogenated aromatic vinyl compound-based elastomer (B) is a hydrogenate of a block copolymer containing a polymer block (a) having a structural unit derived from an aromatic vinyl compound and a polymer block (b) having a structural unit derived from a conjugated diene compound, and the ratio by mass of the polyester-based thermoplastic elastomer (A) to the hydrogenated aromatic vinyl compound-based elastomer (B), (A/B) is 99/1 to 1/99.