中文摘要：

为了研究POSS对聚乙烯（PE）性能的影响,采用分子动力学方法,建立了PE和3种含有不同POSS比例的杂化材料的模型,计算得到了4种聚合物的体积温度曲线,从曲线斜率的转折点得到了材料的玻璃态转变温度（Tg）.然后,通过应力应变涨落方法,求得了4种聚合物的弹性模量随温度的变化曲线.计算结果表明,POSS的加入对PE的Tg影响很小,但是对PE的弹性模量改变很显著.材料的弹性模量随着POSS的比例先减小后增加到最大然后又趋于减小.最后,根据能量各部分的变化,指出了材料的Tg取决于主链的扭转和主链之间的相对运动;而POSS单体与主链之间的范德华作用是材料弹性模量增强的原因.

英文摘要：

The influence of polyhedral oligomeric silsesquioxane （POSS） as a pendant group on polyethylene back- bones was studied with atomistic molecular dynamics simulations. Neat polyethylene and three copolymers with vari- ous ratios of POSS units were modeled, and the volume-temperature curves were obtained. From the break of the slope of the curves, the glass transition temperatures were obtained. Meanwhile, the elastic moduli of the polymers were calculated from the stress and strain fluctuation formula. The results show that the glass transition temperatures of the four polymers are almost the same. However, the elastic modulus first decreases and then increases to the maximum, afterwards descending with the increasing ratio of the POSS content. Based on the analysis of the varia- tion of every part of the potential energy, it was concluded that the torsion of the main chain and the relative move- ment between the chains contribute to the glass transition. On the other hand, the van der Waals interactions be- tween the POSS unit and the main chains play an important role in the enhancement of the elastic modulus.