Dynamics of polymer melts above the glass transition : Monte Carlo studies of the bond fluctuation model
Dynamics of polymer melts above the glass transition : Monte Carlo studies of the bond fluctuation model
复制标题
玻璃化转变以上聚合物熔体的动力学：键波动模型的蒙特卡罗研究
DOI：
10.1021/ma961605b
复制
发表时间：
1997
期刊：
影响因子：
5.5
通讯作者：
K. Binder
中科院分区：
文献类型：
--
作者：
K. Okun;M. Wolfgardt;J. Baschnagel;K. Binder
键长依赖的势能有利于长键的简单立方晶格上的键涨落模型表现出玻璃状冻结的温度降低，许多性质定性类似于实验。本论文研究了该模型的动力学性质（因为它们来自随机跳跃算法），使用配置的过冷聚合物熔体，已仔细平衡的滑动蛇算法。以这种方式，定量可靠的数据，可以获得明显低于以前的工作中的动力学模型，使用随机跳跃算法的平衡，以及在较低的温度。如果各种均方位移，自扩散常数，自相关函数的端到端的矢量，中间非相干散射函数，和单链的动态结构因子进行分析，它被发现，根据Vogel-Fulcher定律的弛豫时间的减慢发生。在分析的不确定度范围内，所有这些时间的Vogel-Fulcher温度相同，0.12 ≤ T 0 ≤ 0.13。特别具有启发性的是劳斯模式的分析，支持这一结论，并进一步产生令人信服的证据的时间-温度叠加原理。结果表明，在过冷熔体中，不同的劳斯模式之间没有静态的互相关。
The bond fluctuation model on the simple cubic lattice with a bond-length dependent potential energy favoring long bonds exhibits a glassy freezing in as the temperature is lowered, many properties being qualitatively similar to experiment. The present paper studies the dynamical properties of the model (as they result from the random hopping algorithm), using configurations of undercooled polymer melts that have been carefully equilibrated by the slithering snake algorithm. In this way quantitatively reliable data can be obtained for distinctly lower temperatures than in the previous work on the dynamics of this model that used the random hopping algorithm for equilibration as well. If various mean-square displacements, the self-diffusion constant, autocorrelation functions of the end-to-end vector, intermediate incoherent scattering functions, and single chain dynamic structure factors are analyzed, it is found that the slowing down of relaxation times occurs according to the Vogel-Fulcher law. Within the uncertainties of the analysis the Vogel-Fulcher temperature of all these times is the same, 0.12 ≤ T 0 ≤ 0.13. Particularly illuminating is an analysis of the Rouse modes, which supports this conclusion and furthermore yields compelling evidence for the time-temperature superposition principle. It is shown that no static cross-correlations develop between different Rouse modes in the undercooled melt.