标题： 分散度对纠缠聚合物从分子动力学模拟中松弛的影响 显示英文标题

标题： Influence of Dispersity on the Relaxation of Entangled Polymers from Molecular Dynamics Simulations

摘要： 非平衡分子动力学模拟用于研究分散聚合物熔体的形变行为，通过跟踪测试链的长度 N = Mw，即重均分子量，在不同分散度的熔体中进行跟踪。 在高应变率下，应力随着分散度的增加而减少，直到临界拉伸比。 流动停止后，松弛是各向异性的：回转半径的平行分量随着分散度的增加而单调减少，但垂直分量表现出非单调行为，在低到中等拉伸比时松弛较快，而在较高拉伸比时随着分散度的增加松弛变慢。 单链结构因子在垂直方向上显示出类似趋势，在分散体系中，中间尺度的松弛较快，而平行分量不受分散度的影响。 这些发现揭示了在远离平衡状态下，中等缠绕聚合物熔体中复杂的、依赖于分散度的各向异性松弛机制。 显示英文摘要

摘要： Nonequilibrium molecular dynamics simulations are used to study the deformation behavior of disperse polymer melts by tracking test chains of length N = Mw, the weight average molecular weight, in melts of varying dispersity. At high strain rates, stress decreases with increasing dispersity up to the critical stretch ratio. After flow cessation, relaxation is anisotropic: the parallel component of the radius of gyration decreases monotonically with dispersity, but the perpendicular component exhibits non-monotonic behavior, with fast relaxation at low to intermediate stretching ratios, and slower relaxation at higher stretching ratios as dispersity increases. Single-chain structure factor shows a similar trend in the perpendicular direction, with fast relaxation at intermediate length scales in disperse systems, while the parallel component remains unaffected by dispersity. These findings reveal the complex, dispersity-dependent anisotropic relaxation mechanisms in moderately entangled polymer melts far from equilibrium.