| 摘要 |
PROBLEM TO BE SOLVED: To provide a polymer improved in the balance of the three requirements, i.e., a low phase transition temperature, a high phase transition heat value and high processability (low molecular weight), and in addition retaining a high melting point. SOLUTION: A butadiene-isoprene copolymer is provided which is a copolymer between 1,3-butadiene and 2-methyl-1,3-butadiene (isoprene), which in the solid state shows a reversible crystal transition phenomenon, whose crystal transition temperature (Ttr) on temperature rising is 55-70°C, and which satisfies the expression:ΔHtr>2×Ttr-35 (whereinΔHtr indicates an endothermic value (J/g) accompanying the crystal transition and Ttr indicates the crystal transition temperature (°C)). COPYRIGHT: (C)2006,JPO&NCIPI
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