Strong and conductive polybenzimidazole composites with high graphene contents

Abstract

Graphene has been considered as an ideal reinforcement agent for polymer composites for a long time, however, strong and highly conductive composites have rarely been reported because of the poor dispersion that results when the loading of graphene is increased to a certain level. In this paper, by combining simple solvent-exchange and solution-casting methods, graphene oxide (GO)/polybenzimidazole composites with high GO contents (up to 40 wt%) are initially prepared. SEM and XRD results demonstrate the good dispersion state and alignment of GO in the composites. Tensile testing reveals that the modulus of the composite increases with the addition of GO as a result of the homogenous dispersion and strong interfacial interactions, while the strength shows a maximum value in the composite with 20 wt% GO. To make the composites conductive, chemical treatment with hydroiodic acid or thermal annealing at 220 °C were carried out on the samples. It was found that the chemical reduction is more effective in improving the conductivities of the composites, but slightly detrimental to the mechanical properties. Although the thermally treated composites show relatively lower conductivities, they possess a higher modulus and strength than the corresponding unreduced and chemically reduced ones. By these efforts, composites with diverse properties, but which are generally mechanically strong and conductive, are fabricated. It is expected that these high-performance composites could find applications in a broad range of technical fields.