Investigation on dielectric and electrical properties of low concentration graphene oxide filled polyurethane nanocomposites

Polymers and their composites are predominantly used as the main insulating material in various electrical power and electronic systems. A polyurethane elastomer (PUE) obtained by two-step polymerization of low molecular weight polypropylene alcohol, MDI (diphenylmethane diisocyanate) and BDO (butanediol) has the potential to become the next generation of smart dielectric materials due to its excellent electrical strength, efficient self-healing capability, and good recyclability. Graphene oxide (GO) are an attractive candidate for functional fillers for these polymers to improve their properties. GO not only has a larger specific surface area relative to conventional nanoparticles, low density, and excellent mechanical strength, but also its base and edges have abundant oxygen-containing functional groups, such as epoxy, hydroxyl, carboxyl, and carbonyl groups. These oxygen-containing functional groups make GO have good compatibility with polymer substrates. In this study, PU/GO nanocomposites are obtained by solution blending method. In order not to affect the mechanical properties of polyurethane, the doping concentration is limited to less than 5% volume fraction. Scanning electron microscopy (SEM) showed that the GO sheets were dispersed uniformly in the polyurethane matrix. The DC conductivity characteristic of the composites was characterized by standard three-electrode testing method. Thermally stimulated depolarization current (TSDC) spectra are used to analyze the relaxation behavior of the composites, and the influence mechanism of doping GO on the conductivity and relaxation behavior of the composites was elucidated.