Breakage of Jammed Suspensions using DC Electric Field*

Application of DC electric fields (EFs) to networked suspensions of non-polar particles dispersed in polar liquid induces network breakage. The particles are soluble at high temperature and upon cooling, nucleate, grow and form interparticle connections. For such materials, we demonstrate that application of EF breaks the network converting the solid-like material to a low viscosity fluid with no yield stress. Maxwell stresses in contact zone between two particles are compressive and must be large enough to cause breakage of particle-particle contacts within the network.

Experiments are performed with model suspensions containing network of low ε particles in high ε continuous phase. Upon application of EF, a reduction of more than one order in viscosity and yield stress has been observed and corresponding breakage and consolidation of microstructure has also been recorded. The extent and rate of breakage of network and corresponding rheological signatures are studied as a function of wax concentration, shear rate, and dielectric constants of the solvent phase. These are correlated to the estimated Maxwells stresses acting on particles to break the network in presence of EF and Mason’s number indicating the dominance of viscous versus electric forces during reduction of viscosity.