Dilatant Behavior of Systems with the Thixotropic Agent Aerosil 380 in the Epoxy Resin Araldite GY260

Abstract

Abstract Model suspension with Aerosil 380 in epoxy resin Araldite GY260 and Aerosil 380 in silicone oil M20000 are compared. The systems with 7.5%, 10% and 12.5% Aerosil 380 in Araldite GY260 show shear thickening flow behavior. A shear induced hydrodynamic force effects at the onset of shear thickening a disorder of the well ordered movement of the Areosil particles in layers. The Areosil particles build-up a pseudo-mixture that lead to a sudden development of a three dimensional structure, i.e. to viscosity incerease. One can assume that the shear thickening can be explained with an order-to-disorder transition. The viscosity increase of the shear thickening region is limited – It can reach topmost the plastic viscosity curve that has to be expected from the beginning. The dilatant system begins in the third straight line section to coincide the viscosity curve of the expected plastic system for the subsequent thixotropic agent concentration.