Modeling the electrical percolation of mixed carbon fillers in polymer blends

A model based on excluded volume theory is proposed for describing the electrical percolation of mixed carbon fillers in polymer blends by adjusting the unit volume of the previous model concerning mixed carbon-filler-filled single polymer systems. An equation capable of predicting the percolation threshold from those of individual carbon fillers in the single matrix polymer is developed from the model and further corrected to suit the actual situation. The corrected equation fits the experimental results obtained from multi-walled carbon nanotubes/carbon black-filled polybutylene terephthalate/styrene–acrylonitrile (SAN), polycarbonate (PC)/SAN and PC/acrylonitrile–butadiene–styrene blends well. The model and equation show clearly the advantages of using both mixed fillers and polymer blends, and can provide an important theoretical basis for designing the structures and predicting the electrical properties of conductive polymer composites.