The present description relates to an olefin block copolymer having excellences in elasticity, heat resistance, and processability. The olefin block copolymer includes a plurality of blocks or segments, each of which includes an ethylene or propylene repeating unit and an α-olefin repeating unit at different weight fractions. In the olefin block copolymer, a first derivative of the number Y of short-chain branches (SCBs) per 1,000 carbon atoms of each polymer chain contained in the block copolymer with respect to the molecular weight X of the polymer chains is a negative or positive number of −1.5×10
−4
or greater; and the first derivative is from −1.0×10
−4
to 1.0×10
−4
in the region corresponding to the median of the molecular weight X or above.
本说明涉及一种具有弹性、耐热性和加工性的烯烃嵌段共聚物。该烯烃嵌段共聚物包括多个块或段,每个块或段包括不同重量分数的
乙烯或
丙烯重复单元和α-烯烃重复单元。在该烯烃嵌段共聚物中,每个聚合物链中每1,000个碳原子所含的短链支化物(SCBs)数量Y的一阶导数相对于聚合物链的分子量X为负数或正数,且为-1.5×10-4或更大;并且在对应于中位数的分子量X或以上的区域内,该一阶导数为-1.0×10-4到1.0×10-4之间。