Abstract With molecular dynamics simulations, nanocomposites were characterized that are comprised of a polyimide (PI) polymer and carbon nanotubes (CNTs) with the same outer diameter but with one, two, or three walls. The simulations indicate that the PI/CNT interaction is strong, regardless of the number of CNT walls, and that there is some degree of alignment of the PI chains near the CNT interface. As the number of CNT walls increased, the density of PI chains near the CNT interface also increased and the average radius of gyration of the PI chains decreased, and these observations were attributed to changes due to the intertube van der Waals interactions. From simulations of the constant force pullout process of the CNT from the PI matrix, the limiting pullout force was calculated to be higher for the triple-walled CNT than for the single-walled one. The interfacial shear strength of the nanocomposites was also calculated from the pullout energy, and the results indicate that increasing the number of walls is a critical factor for enhancing the interfacial stress transfer during tension.

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基于分子动力学模拟的碳纳米管-聚酰亚胺纳米复合材料的界面特性

摘要 通过分子动力学模拟，纳米复合材料被表征为由聚酰亚胺 (PI) 聚合物和碳纳米管 (CNT) 组成，它们具有相同的外径但具有一个、两个或三个壁。模拟表明，无论 CNT 壁的数量如何，PI/CNT 相互作用都很强，并且在 CNT 界面附近存在一定程度的 PI 链对齐。随着 CNT 壁的数量增加，靠近 CNT 界面的 PI 链密度也增加，PI 链的平均回转半径减小，这些观察结果归因于管间范德华相互作用引起的变化。从 PI 矩阵对 CNT 恒力拉出过程的模拟，计算得出，三壁 CNT 的极限拔出力高于单壁 CNT。纳米复合材料的界面剪切强度也由拉出能计算，结果表明增加壁的数量是增强拉伸过程中界面应力传递的关键因素。