Polymer Engineering Faculty Research


Loss of surface and volume electrical conductivities in polymer compounds due to shear-induced migration of conductive particles

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Publication Date

Fall 2003


The loss of surface and volume electrical conductivities of conductive polymer compounds as a result of shear-induced migration of conductive filler particles is elucidated with the help of model equations by considering flow of uniformly mixed conductive polymer compounds through two-dimensional channels, as in injection molding or extrusion of sheets and films. Matrix polymers of shear-thinning nature and non-colloidal conductive particles of spherical shape are considered. The effect of particle migration is found to be most severe in the case of compositions around the percolation threshold—an otherwise uniformly mixed conductive compound turns into an insulator because of migration of conductive particles from the surface to the bulk. In addition, the extent of migration of particles and consequently the loss of conductivity are found to be the greatest for Newtonian polymer matrices, where the gradients of shear stress are the highest. The extent of migration gradually reduces as the polymer becomes more shear-thinning.



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