ABSTRACT An unmodified polypropylene (PP) model and a modified model with 2% nano-silicon dioxide content were built initially, and then the mechanical parameters of the two models were compared by molecular dynamics simulation. The results show that the modulus of the modified model are larger than those of the unmodified model, and the ductility of both models is stable. The yield point of the modified model was increased by 8.5% at 25°C and 14.2% at 100°C compared with that of the unmodified model, respectively. Its Young's modulus is also increased. The main mechanism is that the addition of nanoparticles results in the decrease in the free volume of PP molecules, and the interaction between the strong polar –OH groups and the H atoms in a large number of –CH3 groups in PP molecules increases the intermolecular force in the whole model, which leads to the improvement of mechanical properties. Higher temperature leads to the intensification of molecular motion, which increases the distance between molecules, decreases the cohesive energy and reduces the mechanical properties of the model. The results of this paper can provide some reference for further research on the improvement of mechanical properties of nano-doped modified materials.

中文翻译：

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纳米二氧化硅改善聚丙烯力学性能的微观机理研究

摘要 首先建立了未改性聚丙烯（PP）模型和纳米二氧化硅含量为2%的改性模型，然后通过分子动力学模拟比较了两种模型的力学参数。结果表明，修正模型的模量大于未修正模型的模量，两种模型的延性均稳定。与未修改模型相比，修改模型的屈服点在 25°C 和 100°C 时分别提高了 8.5% 和 14.2%。其杨氏模量也增加。主要机制是纳米粒子的加入导致PP分子的自由体积减小，强极性的-OH基团与PP分子中大量-CH3基团中的H原子相互作用增加了分子间作用力在整个模型中，从而提高机械性能。较高的温度会导致分子运动加剧，从而增加分子间的距离，降低内聚能并降低模型的机械性能。本文研究结果可为进一步研究纳米掺杂改性材料力学性能的提高提供一定的参考。