Nonlinear rheology of highly entangled polymer liquids: Step shear damping function
Nonlinear rheology of highly entangled polymer liquids: Step shear damping function
复制标题
高度缠结聚合物液体的非线性流变学：阶跃剪切阻尼函数
DOI：
10.1122/1.1332384
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发表时间：
2001
影响因子：
3.3
通讯作者：
L. Archer
中科院分区：
文献类型：
--
作者：
M. T. Islam;J. Sánchez;L. Archer
用机械流变法和双折射偏振法研究了纠缠聚苯乙烯/邻苯二甲酸二乙酯溶液中非线性阶跃剪切弛豫模量G(t,γ)=σ(t,γ)/γ。我们提出了这样一个问题：阶跃剪切阻尼函数h(γ)=G(t,γ)/G(t)是否适用于纠缠类流体？实验结果给出了明确的否定答案，并且实际上表明纠缠聚合物液体中的阻尼函数随聚合物分子量和浓度连续变化。在弱至中度纠缠溶液中，N/Ne=Mw¯φ1.3/Me0≤11,h（γ）的实验结果与Doi-Edwards理论预测hDE-IA （A型阻尼）一致。然而，在更高的纠缠密度下，阻尼函数变得比hDE-IA越来越软，特别是在低应变（C型阻尼）下。从A型到C型阻尼行为的转变伴随着在实验G(t,γ)h(γ)−1 plo中出现复杂的随时间变化的交叉模式。
Nonlinear step shear relaxation moduli G(t,γ)=σ(t,γ)/γ in a series of entangled polystyrene/diethylphthalate solutions are studied using mechanical rheometry and birefringence polarimetry measurements. We pose the question: Is the step shear damping function h(γ)=G(t,γ)/G(t) universal for fluids in the class entangled liquids? The experimental results provide a clear answer in the negative, and in fact show that the damping functions in entangled polymer liquids continuously vary with polymer molecular weight and concentration. In weak to moderately entangled solutions, N/Ne=Mw¯φ1.3/Me0⩽11, experimental h(γ) results are in accord with the Doi–Edwards theoretical prediction, hDE-IA (type A damping). At higher entanglement densities, however, damping functions become progressively softer than hDE-IA, particularly at low strains (type C damping). The transition from type A to type C damping behavior is accompanied by the appearance of a complex time-dependent crossing pattern in experimental G(t,γ)h(γ)−1 plo...