A Links‐Nodes‐Blobs Model for Conductive Polymer Composites

A Links‐Nodes‐Blobs (L‐N‐B) model, based on the fractal and percolation concepts, is used to study the electrically conductive mechanism of conductive filler loaded polymer composites. The change in the conductivity of polymer composites during the mixing process can be explained as the competition between the breakdown of filler aggregates and the diffusion of ingredients of matrix material and impurities onto the surface of the filler. The value of the fractal dimension μ, which is the exponent in the power‐law relationship of the electrical conductivity σ = σ₀·(ϕ – ϕ_c)^μ, is calculated as 1.88. This value is close to the values obtained directly from experiments or from other simulations. The positive temperature coefficient (PTC) behavior in the conductivity of composite material is also explained by this model as the breakdown of the conductive filler network. If the thermo‐expansion induced strain is greater than the apparent on‐set strain ε_onset = mQ + 2 G/2d G·ε_b of the L‐N‐B model, a strong PTC effect would happen.