Non-equilibrium relaxation and tumbling times of polymers in semidilute solution
Non-equilibrium relaxation and tumbling times of polymers in semidilute solution
复制标题
聚合物在半稀溶液中的非平衡弛豫和翻滚时间
DOI：
10.1088/0953-8984/24/28/284131
复制
发表时间：
2012
期刊：
影响因子：
--
通讯作者：
R. Winkler
中科院分区：
文献类型：
--
作者：
Chien;G. Gompper;R. Winkler
采用大尺度细观流体动力学模拟方法，研究了剪切流作用下单体聚合物在稀溶液和半稀溶液中的端对端翻滚动力学。端到端的矢量松弛时间是沿流、梯度和涡度方向确定的。沿流动和梯度方向，相关函数在短时间内以正弦调制呈指数衰减。在稀溶液中，各方向的衰减时间非常相似。而在半稀溶液中，不同方向的松弛行为有较大差异，涡度方向的松弛时间最长，流动方向的松弛时间最短。在高剪切速率下，不同的松弛时间表现出与指数−2/3的指数剪切速率的幂函数关系。在定量上，松弛时间等于从旋转半径分量沿流动方向和梯度方向的波动的互相关函数中提取的翻滚时间。
The end-over-end tumbling dynamics of individual polymers in dilute and semidilute solutions is studied under shear flow by large-scale mesoscale hydrodynamic simulations. End-to-end vector relaxation times are determined along the flow, gradient, and vorticity directions. Along the flow and gradient directions, the correlation functions decay exponentially with sinusoidal modulations at short times. In dilute solution, the decay times of the various directions are very similar. However, in semidilute solutions, the relaxation behaviors are rather different along the various directions, with the longest relaxation time in the vorticity direction and the shortest time in the flow direction. The various relaxation times exhibit a power-law shear-rate dependence with the exponent − 2/3 at high shear rates. Quantitatively, the relaxation times are equal to the tumbling times extracted from cross-correlation functions of fluctuations of radius-of-gyration components along the flow and gradient direction.