不同微观结构聚丁二烯橡胶的自由基接枝反应

Radical grafting reaction of polybutadiene rubber with different microstructure

以过氧化苯甲酰(BPO)为引发剂,2,2,6,6-四甲基哌啶-1-氧基自由基(TEMPO)为自由基捕捉剂,进行3种低相对分子质量模型聚丁二烯,即高乙烯基聚丁二烯橡胶(HVPB)、高反式聚丁二烯橡胶(HTPB)及高顺式聚丁二烯橡胶(HCPB)的自由基接枝反应,并利用傅里叶变换红外光谱和核磁共振氢谱对模型聚丁二烯接枝产物的微观结构、TEMPO及BPO残基的含量进行了分析。结果表明,聚丁二烯的自由基接枝反应初期主要以夺氢反应为主,随着反应时间的延长,自由基加成反应占比增加,增加幅度由高到低依次为HCPB、HVPB、HTPB。聚丁二烯的1,2-结构有利于夺氢反应,而加成反应更易在顺式1,4-结构上进行。

The radical grafting reaction of three kinds of low relative molecular mass model polybutadiene(PB), high 1,2-polybutadiene(HVPB), high trans-1,4-polybutadiene(HTPB) and high cis-1,4-polybutadiene(HCPB), was carried out using benzoyl peroxide(BPO) as radical initiator and 2,2,6,6-tetramethylpiperidine-1-oxyl(TEMPO) as radical trapper. The content of microstructure, BPO residue and TEMPO of grafted PB products were characterized by Fourier transform infrared spectroscopy and proton nuclear magnetic resonance. The results showed that the abstracting hydrogen reaction dominated the radical grafting reaction of PB at the initial stage and the radical addition reaction became stronger as the increase of reaction time. The raise order of addition reaction from high to low was HCPB, HVPB and HTPB. The 1,2-unit of PB was conducive to the abstracting hydrogen reaction, while the cis-1,4-unit of PB tended to undergo the radical addition reaction.