Influence of particle arrangement on the permittivity of an elastomeric composite

Elastomers are used as dielectric layers contained between the parallel conductive plates of capacitors. The introduction of filler particles into an elastomer changes its permittivity epsilon. When particle organization in a composite is intentionally varied, this alters its capacitance. Using numerical simulations, we examine how conductive particle chains introduced into polydimethylsiloxane (PDMS) alter epsilon. The effects of filler volume fraction psi, interparticle d and interchain spacing a, zigzag angle theta between adjacent particles and overall chain orientation, particle size r, and clearance h between particles and the conductive plates are characterized. When filler particles are organized into chainlike structures rather than being just randomly distributed in the elastomer matrix, epsilon increases by as much as 85%. When particles are organized into chainlike forms, epsilon increases with increasing and a, but decreases with increasing d and theta. A composite containing smaller particles has a higher epsilon when psi < 9% while larger particles provide greater enhancement when is larger than that value. To enhance epsilon, adjacent particles must be interconnected and the overall chain direction should be oriented perpendicular to the conductive plates. These results are useful for additive manufacturing on electrical applications of elastomeric composites. (C) 2017 Author(s).