Properties characterisation of polycarbonate and multi‐walled carbon nanotubes composites prepared by solution technique

Abstract Polycarbonate (PC) and multi‐walled carbon nanotubes (MWNTs) composites were prepared by solution method where 0–20% w/w MWNTs were added into two types of PC solutions, i.e. a low and a high molecular weight solution. The composites were processed into plastic sheets using a compression moulding technique in order to study their mechanical, electrical, physical, and rheological properties. The results showed that addition of MWNTs at 1% w/w enhanced the tensile strength and modulus by up to 23 and 75%, respectively, and reduced their electrical resistivity significantly from being an insulator (1 × 1016 − 1 × 1017 Ω‐cm) to a semi‐conductor (8 × 108 Ω‐cm), indicating a percolation threshold. A slight improvement in the mechanical properties was observed at up to 4% w/w MWNTs; however, the volume resistivity remained unchanged. As the amount of MWNTs increased >4% w/w, the mechanical properties drastically deteriorated because of the MWNTs agglomerating and segregating onto the surfaces. The segregation of the agglomerates was also supported by the surface resistivity and shear viscosity results, which decreased as MWNTs increased. MWNTs were found to interact better with the low molecular weight PC matrix and produced more homogeneous composites. The studies of composite colour and MWNTs dispersion confirmed the findings of both mechanical and electrical properties. This research demonstrates the possibility of preparation of PC and MWNTs composites at high MWNTs concentrations, which can be very useful for a master batch process. © 2015 Curtin University of Technology and John Wiley & Sons, Ltd.