Provided are: a polymer blend which includes an organic polymer having a reactive silicon-containing group and which can give cured objects excellent in terms of elongation property and stress relaxation; a composition comprising the polymer blend, a specific filler, and a curing catalyst; a sealant comprising the composition; and a sealant for tires. A polymer blend which includes an organic polymer having a bifunctional reactive silicon-containing group of a specific structure is mixed with given proportions of a polyoxyalkylene (A) which has a number-average molecular weight of 13,000 or higher and 100,000 or lower, has a reactive-silicon-containing-group equivalent Eqa of 0.010 mmol/g or more and 0.29 mmol/g or less, and contains more than one silicon-containing group per molecule and a polyoxyalkylene (B) which has a number-average molecular weight of 3,000 or higher and 25,000 or lower, has a reactive-silicon-containing group only at one end, and has a reactive-silicon-containing-group equivalent Eqb of 0.03 mmol/g or more and 0.58 mmol/g or less.
本文提供了:一种聚合物混合物,其中包括一种具有含
硅活性基团的有机聚合物,该聚合物混合物可使固化物具有优异的伸长性能和应力松弛性能;一种组合物,其中包括该聚合物混合物、一种特定填料和一种固化催化剂;一种密封剂,其中包括该组合物;以及一种轮胎密封剂。一种聚合物混合物,它包括具有特定结构的双官能团活性含
硅基团的有机聚合物与给定比例的聚氧亚烷基 (A) 混合,聚氧亚烷基 (A) 的数均分子量为 13,000 或以上和 100,000 或以下,其活性含
硅基团当量 Eqa 为 0.010 mmol/g 或以上和 0.29 mmol/g 或更低,且每个分子含有一个以上的含
硅基团,以及聚氧亚烷基 (B) 的数均分子量为 3,000 或更高,25,000 或更低,仅在一端具有活性含
硅基团,且活性含
硅基团当量 Eqb 为 0.03 mmol/g 或更高,0.58 mmol/g 或更低。