Abstract: The thermal oxidation process of SBS is tracked by in-situ FTIR; meanwhile，the reaction parameters of SBS oxidation kinetics are calculated by thermal analysis kinetics. The results show that there is no chain scission and degradation occurred in nitrogen atmosphere below 160℃; while，in oxygen atmosphere，thermal oxidative degradation and random chain scission occur in PB segment of SBS; PS segment of SBS has excellent anti-oxidation performance and it can’t be oxidized when temperature is below 300℃. The α-H beside the double-bond has great activity，which is easy to be oxidized. The results also show that both of chain scission and de-polymerization occur in the thermal oxidation reaction. Auto-oxidation is the main feature of SBS thermal aging oxidation process. The mechanism of the reaction is freely-chained reaction， which includes chain initiation，chain growth and chain termination. After the reaction experiences the induction period of initial free radical，SBS is oxidized rapidly and degraded severely.

Key words: thermal oxidation of SBS, in-situ FTIR, thermal analysis kinetics, auto-oxidation

摘要： 采用原位红外技术跟踪SBS热氧化过程，同时通过热分析动力学技术计算了SBS的氧化动力学反应参数。 研究表明，160℃以下时，氮气氛围中的SBS无降解断链现象发生。在氧气氛围下，SBS中的PB段发生热氧化降解 及无规则断链。在300℃以下时，SBS中的PS段抗氧性能优异，无氧化发生;PB段中双键旁的α氢原子有很大活 性，是氧化反应的进攻点，其热氧化降解同时存在解聚和无规断链，自动氧化反应是SBS热氧老化的主要特征，反 应机理为自由链式，反应过程包括链引发、链增长和链终止，反应经过初始自由基的诱导期后，SBS迅速被氧化并发 生严重降解。

关键词: SBS热氧化, 原位红外, 热分析动力学, 自动氧化