Reduced percolation threshold of conductive adhesive through nonuniform filler localization: Monte Carlo simulation and experimental study

Abstract

Adhesive nickel based polymer composites were investigated experimentally and by computational modelling with respect to optimization of electrical and mechanical properties. Utilization of polymer blends with an optimized combination of epoxy resin (ER) and polydimethylsiloxane (PDMS) resulted in a reduced electrical percolation threshold (EPT) from 7.9 up to 3.7 vol % of Ni and increased the direct current (DC) conductivity of the composites by 7 orders of magnitude. At the same time, adhesion of the composites was enhanced by 20% and impact strength by 75% due to the PDMS addition. The observed effect of the EPT reduction is determined by the preferred localization of conductive Ni particles near the ER phase, specifically on the ER/PDMS interface. Prior to the composite preparation, the polymer composites were simulated by the Monte Carlo method and were evaluated by two independent methods: i) the growth of the conductive networks was examined by the size of aggregates via aggregation number (script in Python) ii) the conductivity of the polymer composites was calculated via finite element method (FEM, Digimat-FE 6.1.1). The computational simulations correlated well with the experimentally determined EPT and conductivity of the polymer composites. © 2021 Elsevier Ltd