Influence of matrix conductivity and Coulomb blockade effect on the percolation threshold of insulator–conductor composites

The percolative behavior of PVDF–Ag composites obtained using external mixing of PVDF with pre-made Ag and in situ formed Ag were studied. Composite prepared by the in situ formation of Ag had a percolation threshold of 7 vol% as against 13, 14, and 16 vol% for composites prepared by ultrasonic mixing pre-made Ag powders of about 100 nm, 3.5 μm and 5 μm respectively with PVDF. The homogenous dispersion of in situ Ag nanoparticles in PVDF leads to percolation at lower filler loading. The observed variations in dielectric properties are explained based on size and extent of agglomeration of Ag and method of preparation of the composites. The influence of matrix characteristics on the properties of composite is also brought out.