Institute of Complex Systems-3, Forschungszentrum Jülich, 52428 Jülich, Germany.
Soft Matter. 2019 Jan 30;15(5):833-841. doi: 10.1039/c8sm01925h.
The linear and nonlinear rheological behavior of two rod-like particle suspensions as a function of concentration is studied using small amplitude oscillatory shear, steady shear and capillary breakup extensional rheometry. The rod-like suspensions are composed of fd virus and its mutant fdY21M, which are perfectly monodisperse, with a length on the order of 900 nm. The particles are semiflexible yet differ in their persistence length. The effect of stiffness on the rheological behavior in both, shear and extensional flow, is investigated experimentally. The linear viscoelastic shear data is compared in detail with theoretical predictions for worm-like chains. The extensional properties are compared to Batchelor's theory, generalized for the shear thinning nature of the suspensions. Theoretical predictions agree well with the measured complex moduli at low concentrations as well as the nonlinear shear and elongational viscosities at high flow rates. The results in this work provide guidelines for enhancing the elongational viscosity based on purely frictional effects in the absence of strong normal forces which are characteristic for high molecular weight polymers.
本文采用小振幅振荡剪切、稳态剪切和毛细射流拉伸流变仪研究了两种棒状颗粒悬浮液的线性和非线性流变行为与浓度的关系。棒状悬浮液由 fd 病毒及其突变体 fdY21M 组成，它们具有完美的单分散性，长度约为 900nm。这些颗粒具有半刚性，但其持久长度不同。实验研究了刚性对剪切和拉伸流动中流变行为的影响。详细比较了线性粘弹性剪切数据与用于线状链的理论预测。将拉伸性能与巴切勒理论进行了比较，该理论针对悬浮液的剪切变稀性质进行了推广。理论预测与在低浓度下测量的复模量以及在高流速下的非线性剪切和拉伸粘度吻合良好。本工作的结果为在不存在高分子量聚合物特征的强法向力的情况下，基于纯摩擦效应来提高拉伸粘度提供了指导。
