Apparent yield stress in rigid fibre suspensions: the role of attractive colloidal interactionsReport as inadecuate

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1 LPMC - Laboratoire de physique de la matière condensée 2 IRDL - CNRS FRE 3744 - Institut de Recherche Dupuy de Lôme 3 Department of Mathematical Physics

Abstract : This work is focused on the modelling of the shear and normal stresses in fibre suspensions that are subjected to a simple shear flow in the presence of short-range lubrication forces, van der Waals and electrostatic forces, as well as solid friction forces between fibres. All these forces are weighed by the contact probability. The theory is developed for attractive fibres with van der Waals interaction dominating over electrostatic repulsion. The model predicts a simple Bingham law for both the shear stress and the first normal stress difference with the apparent shear and normal yield stresses proportional, respectively, to the second and the third power of particle volume fraction. The model is applied to the experimental data of Rakatekar et al. Adv. Mater 21, 874-878 2009 and Natale et al. AIChE J. 60, 1476-1487 2014 on the suspensions of carbon nanotubes dispersed in a Newtonian epoxy resin. It reproduces well the quadratic dependency of the apparent yield stress on particle volume fraction σ Y ∝φ^2 for average particle aspect ratios of r=160 and 1200, while it underpredicts the power-law exponent for rD80 always predictingφ^2 behaviour instead of φ^3.2

Author: S. Bounoua - E. Lemaire - J. Férec - G. Ausias - A. Zubarev - P. Kuzhir -



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