摘要
建立一种构型模拟与力学性能模拟相结合的连续模拟方法研究了三元共混物(两种均聚物与一种共聚物)中交替共聚结构与嵌段共聚结构对力学性能的影响。通过蒙特卡罗模拟获得其构型,然后将该构型作为弹簧格子模型的数据输入,模拟三元共混体系的微观结构与力学性能。模拟结果表明:交替共聚物在体系中更倾向于在两种均聚物的界面处自我缠绕,而嵌段共聚物的两端分别渗透进与之相容的均聚物体相中;三元共混物的力学性能与其内部的两相界面结构相关;应变在交替共聚物体系中均匀分布,导致更多的断裂发生在体相中,交替共聚物体系比嵌段共聚物体系力学性能更强且更具韧性。这种连续模拟方法为研究材料组成与力学性能之间的关系提供了一种新方案。
Most homopolymers are incompatible with each other,which limits the mechanical properties of the binary blend.A method to solve this problem is to add a copolymer compatibilizer which is compatible with both initial homopolymers.A continuous simulation method combining Monte Carlo simulation with lattice spring model(LSM)is adopted to study the influence of the architecture of copolymer compatibilizer on the mechanical properties of homopolymer blends.In this work,a Monte Carlo simulation combining cavity diffusion with bond length fluctuation algorithm was adopted to simulate the morphologies and the micro-connections between polymer units,and then the stimulated results directly served as the input of LSM,which is the most important innovation of this work.The mean-square radii of gyration of alternating copolymers and diblock copolymers are 6.59 and 12.15,respectively.Simulated results show that both diblock copolymer and alternating copolymer act as the efficient compatibilizer in the ternary blends.The alternating copolymer chains are inclined to entangle with each other and are distributed on the interfaces of homopolymer microphases,while each block of the diblock copolymer is penetrated into the pure phases.Simulated results also reveal that the different interfacial structures affect the strain and stress distribution of the systems.The strain and stress in the alternating system are higher than those in the diblock system.It is noticeable that the fractures tend to distribute on the spherical surface in the diblock system,while the fractures are more probable to occur in the matrix phase all the time in the alternating system.Both the strength and the toughness of the alternating copolymer compatibilizer system are larger than those of the diblock copolymer compatibilizer system.The continuous simulation method in this work has been proven to be a feasible tool to predict the mechanical properties of materials according to the real composition.
引文
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