聚丁二烯橡胶接枝苯乙烯本体自由基聚合机理

采用傅里叶变换红外光谱法和碘值法分析了在热引发和化学引发方式下，低顺式和高顺式聚丁二烯橡胶接枝苯乙烯聚合物的双键结构和含量，确定了橡胶接枝苯乙烯本体自由基聚合机理。结果表明，热引发时，接枝机理主要是自由基夺取橡胶链上α氢原子；而化学引发时，同时存在自由基与橡胶双键加成的机理。橡胶的结构不同导致接枝点的位置差异，在低顺式聚丁二烯橡胶体系中，自由基以夺取反式-1，4-结构和1，2-乙烯基结构为主，而在高顺式聚丁二烯橡胶体系中。自由基以夺取顺式-1，4-结构为主。

Mechanism of bulk free-radical grafting polymerization of styrene onto polybutadiene

The bulk free-radical grafting polymerization of styrene onto polybutadiene were carried out by using chemical or thermal initiations. Mechanism of the grafting polymerization was studied by the infrared spectra and iodimetric analysis of the double-bond microstructure of the obtained graft-copolymer. The results showed that the main grafting reaction was transfer of radicals to the hydrogen atoms in the allyl position of rubber chains when thermal initiation. However, the addition of the residual carbon-carbon double bonds existed also when chemical initiation. Moreover, the grafting sites were dependent on the double-bond microstructure in rubbers. With the low cis-rubber, the primary radicals preferred to attack the double-bonds in trans-1,4-and vinyl-1,2-unit; while with the high cis-rubber, the radicals mainly attacked the double-bonds in cis-1,4-unit.