Shear induced demixing in bidisperse and polydisperse polymer blends: Predictions from a multifluid model
Shear induced demixing in bidisperse and polydisperse polymer blends: Predictions from a multifluid model
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DOI：
10.1122/8.0000036
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发表时间：
2020-11-01
影响因子：
3.3
通讯作者：
Gary Leal, L.
中科院分区：
文献类型：
--
作者：
Peterson, Joseph D.;Fredrickson, Glenn H.;Gary Leal, L.
鉴于双分散和多分散缠绕线性聚合物本构模型的最新进展，我们提出了一种新的“多流体”推广，用于非均匀聚合物共混流动的经典双流体近似。作为模型的应用，我们考虑了双分散和对数正态分子量分布共混物中剪切诱导分离(SID)不稳定性的线性和非线性动力学预测。我们发现，即使在组分链之间没有任何化学对比的情况下，如果两个链的大小有足够的对比，施加的流动也可以引起分离不稳定性。SID的下限多分散度与通过链之间的对比(例如，多分散度指数减1)衡量的弹性力(k(B)T/纠缠)超过混合的熵力(k(B)T/链)的点一致。对于双分散共混物，我们证明了SID的非线性动力学与先前在纠缠聚合物溶液中SID的非线性动力学非常相似。(C)2020年香港流变学学会。
In light of recent advancements in the constitutive modeling of bidisperse and polydisperse entangled linear polymers, we present a new "multifluid" generalization of the classic two-fluid approximation for flows of inhomogeneous polymer blends. As an application of the model, we consider predictions for the linear and nonlinear dynamics of shear induced demixing (SID) instabilities in blends with bidisperse and log-normal molecular weight distributions. We find that even in the absence of any chemical contrast between component chains, an imposed flow can induce a demixing instability provided there is sufficient contrast in the size of the two chains. The lower bound polydispersity for SID coincides with the point where elastic forces (k(B)T per entanglement) scaled by the contrast between chains (e.g., polydispersity index minus one) exceed the entropic forces for mixing (k(B)T per chain). For bidisperse blends, we show that the nonlinear dynamics of SID strongly resemble what has previously been shown for SID in entangled polymer solutions. (C) 2020 The Society of Rheology.