不同氢化度氢化丁腈橡胶的结构表征与分子模拟

Characterization and Molecular Simulation of HNBR with Different Hydrogenation Degree

通过核磁共振波谱(1H NMR)、红外光谱(IR)及热分析等方法研究了不同氢化度氢化丁腈橡胶(HNBR)分子结构之间的差异,结果表明,在丁腈橡胶(NBR)加氢过程中,聚丁二烯上的乙烯基加氢速率最快,其次是反式1,4结构,顺式1,4结构的加氢速率最慢,而腈基基本不发生氢化反应.采用核磁共振谱法对不同氢化度HNBR中不同链段的含量进行定量分析,依据此结果建模并进行分子模拟计算,得到不同氢化丁腈橡胶的密度、内聚能密度(CED)和玻璃化转变温度(Tg)等参数,模拟值与实验结果吻合.实验结果表明,随着氢化度的增加,HNBR的热氧化稳定性逐渐增加,这主要是由于氢化度增加后分子链中双键含量逐渐减少而CED增加的缘故.分子模拟可以有效地计算出多种结构参数,为共聚橡胶材料的制备与加工提供基础数据及理论指导.

By combining hydrogen nuclear magnetic resonance （ ^1H NMR）, infrared （IR） spectroscopy and thermal analysis, the microstructures of hydrogenated nitrile rubber（HNBR） with different hydrogenation de- gree（HD） were investigated. The result indicated that the rates of hydrogenation reactions of different func- tional groups were different in the sequence of the highest rate of vinyl group in polybutadiene, the second rate of trans-1,4-unit group and the lowest rate of cis-1,4-unit group. The nitrile groups were almost stable during the hydrogenation process. By 1H NMR experiment, the contents of various groups in HNBR with different HD were quantitatively analyzed. These results were introduced to construct proper polymer chains in molecular dynamics simulation（MD） which contributed to calculate various parameters such as density, cohesion energy density（ CED）, and glass-transition temperature（ Ts） , etc, agreed well with experimental results. The results showed that the improvement of thermal stability of HNBR with the increase of HD was due to the decrease of double bonds content and increase of CED. The good agreement between experimental and theoretical simula- tion results indicated that the MD can effectively calculate the structure parameters, provided fundamental data and theoretical direction for the preparation and processing of copolymerized rubber materials.