聚合物共混体系动态力学松弛的分子动力学模拟  

Molecular dynamical simulation on dynamical mechanical relaxation of polymer blend system

作　　者：周彬[1] 刘咏松[1] 汪洋[1] ZHOU Bin;LIU Yongsong;WANG Yang(School of Sciences, Zhejiang Sci-Tech University, Hangzhou 310018, China)

机构地区：[1]浙江理工大学理学院

出　　处：《浙江理工大学学报（自然科学版）》2019年第1期42-48,共7页Journal of Zhejiang Sci-Tech University(Natural Sciences)

摘　　要：根据Green-Kubo函数和平衡态分子动力学算法,推导应力与剪切模量之间的方程,获得平衡态的模拟计算算法。采用该平衡态分子动力学模拟分别定量计算在一定时间尺度内均聚物体系和聚合物共混体系的剪切模量,探讨聚合物共混体系的动态力学松弛过程。结果表明:短链或分子链刚度小的均聚物松弛过程的剪切模量小于长链或分子链刚度大的均聚物松弛过程的剪切模量;在聚合物中添加分子链刚度小的短链均聚物,可减小聚合物的损耗模量,即减少聚合物松弛过程的能量耗散,从而在一定程度上提高聚合物的粘弹性。并且随着短链均聚物链长的减少以及短链均聚物体积分数的增大,该共混体系的能量损耗减小的程度增大。Based on the Green-Kubo function and equilibrium molecular dynamics algorithm,the equation between the stress and the shear modulus was deduced and a novel equilibrium molecular dynamics simulation was developed.This equilibrium molecular dynamics simulation was applied to quantitatively calculate the shear modulus of homopolymer system and polymer blend system at a certain time scale,and the dynamic relaxation process of the polymer blend system was discussed.The simulation results show that the shear modulus of the relaxation.process of homopolymer with short chain or low stiffness is smaller than that of the relaxation process of homopolymer with long chain or high stiffness. Adding the homopolymer with short chain and low stiffness into the polymer can decrease the loss modulus,and reduce the energy dissipation in the dynamical relaxation process,thereby improving the viscoelasticity of polymer to certain degree.Moreover,with the decrease of the length of short chain homopolymer and the increase of the volume fraction of short chain homopolymer,the degree of energy dissipation of the blend system increases.

关 键 词：分子动力学模拟 动态力学松弛 聚合物共混体系 粘弹性 

分 类 号：O469[理学—凝聚态物理]