Department of Chemical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.
Phys Rev Lett. 2010 Nov 12;105(20):208302. doi: 10.1103/PhysRevLett.105.208302. Epub 2010 Nov 9.
Stress relaxation in unlinked ring polymer melts poses an important challenge to our theoretical understanding of entangled polymer dynamics. Recent experiments on entangled unlinked ring melts show power-law stress relaxation with no hint of a rubbery plateau, usually the hallmark of entangled polymers. Here we present a theory for stress relaxation in rings analogous to the successful approach for star polymers. We augment our theory with mesoscale Monte Carlo dynamics simulations of equivalent "lattice animal" configurations. We find a stress relaxation function G(t)∼t(-α) with α≈1/2 consistent with experiment, emerging ultimately from the disparate relaxation times of more- and less-central portions of ring conformations.
无缠结环状聚合物熔体的应力松弛对我们理解缠结聚合物动力学的理论提出了重要挑战。最近对无缠结环状熔体的实验表明，应力松弛呈现幂律形式，没有出现通常是缠结聚合物特征的橡胶平台。在这里，我们提出了一种与成功的星型聚合物方法类似的环状聚合物的应力松弛理论。我们用等效的“格子动物”构型的介观蒙特卡罗动力学模拟来扩充我们的理论。我们发现应力松弛函数 G(t)∼t(-α)，其中 α≈1/2，与实验结果一致，这最终源于环状构象中更多和更少中心部分的不同松弛时间。
