A Conductive Performance Simulation Of Microscopic Network In The Polymer Composites

Ordinary polymer composites have good physical properties, such as high strength, light weight, corrosion resistance, etc. But they have poor conductive properties on the other hand. The electrical conductivity of composites can increase by adding metal or carbon conductive additives in polymer materials. The conductive polymer composites are widely used and focused by researchers. As the simulation analysis can be used to predict the experimental results and the conditions can be changed flexibly in the simulation research process, simulation analysis of composite materials is a very important research method.This paper analyzes the conductive performance of the composite by considering the composite percolation threshold and conductivity of the composites. The morphology and concentration of the additives are several important factors that influence the electrical properties of polymer composites. Through modeling and simulation, we can study the effect of additives on the conductive properties of composites. In this paper, carbon nanotubes are used as the conductive additives as they have excellent electrical conductivity and high aspect ratio features.The simulation is based on three-dimensional space, and the random distribution of the additives in the substrate is conducted by Monte Carlo method. The 3D model is to study how the additives' shape and concentration influence the percolation threshold and conductivity of the polymer composites. In this paper, the carbon nanotubes are randomly distributed in the RVE(Representative volume element). RVE is seen as a polymer substrate of a conductive polymer composite. When the carbon nanotube concentration reaches a certain level, a conducting network appears in RVE and the composite material turns into a conductor from an insulator. At that moment, the concentration of carbon nanotube is conductive threshold concentration. The simulation results show that the percolation threshold of carbon nanotube with a diameter of 3um and a diameter of 50 nm is about 1.2% and the percolation threshold is about 0.37% for carbon nanotube with a diameter of 10 um and a diameter of 40 nm. With the increasing of the carbon nanotubes concentration, the conductivity of the network increases non-linearly. The relationship between the concentration of carbon nanotube and the conductivity basically conforms to the classical percolation theory. At the same time, higher aspect ratio is benefit to combine carbon nanotubes, which results to a higher conductivity of the polymer composites.