Electrical Property of Carbon Nanotubes/Epoxy Resin/Polyetherimide Composites with Inverted-Phase Structure

Carbon nanotubes (CNTs) selective dispersion and electrical properties of one kind of thermoplastic/thermosetting polymer composite consisting of polyetherimide (PEI) and epoxy resin (EP) were investigated. The results showed that, in the CNTs/EP/PEI composite, under control of thermodynamics, CNTs are preferably dispersed in PEI-rich phase, and an inverted phase structure is obtained with continuous PEI-rich phase and separated EP phase as globular shapes. And this microstructure helps to achieve a very low percolation threshold of 0.3wt% CNTs in the composite. The composites at CNTs contents over the percolation threshold, have a high dielectric constant of around 100, which first decreases slightly and the drop rapidly into a platform with increasing frequency from beginning.