SBS热氧老化动力学研究

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。

Study on Thermal Oxidative Aging Kinetics of SBS

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.