Effect of organoclay on morphology and electrical conductivity of PC/PVDF/CNT blend composites

In this work, different contents of the organoclay (0.05-0.25 wt%) were introduced into the polycarbonate/poly(vinylidene fluoride)/carbon nanotube (PC/PVDF/CNT) blend composites by diluting the master batches of the PC/organoclay and the PVDF/CNT through melt-compounding in an internal mixer. In the blend composites, the weight fraction ratio between PC and PVDF was maintained at 40/60, and the content of the CNTs was varied from 0.1 to 0.5 wt%. The morphologies of the blend composites and the dispersion states of the nanofillers were characterized using scanning electron microscope and transmission electron microscope. Differential scanning calorimetry was used to investigate the crystallization behaviors of different blend composites so that the selective localization of the CNTs could be proved further. The results showed that with the presence of the CNTs and/or the organoclay, the blend composites showed the apparent morphological change from a typical sea-island structure to the quasi-cocontinuous structure. Specifically, at the organoclay content of 0.1 wt%, most of the CNTs selectively located at the blend interface. The electrical resistivity was measured and the results showed that organoclay showed apparent influence on the electrical resistivity of the blend composites. Namely, the volume resistivity decreased with increasing organoclay content until a minimum value was achieved, then it increased gradually with further increasing organoclay content. Specifically, all the blend composites exhibited the minimum electrical resistivity at the 0.1 wt% organoclay. Furthermore, a very small percolation threshold of the CNTs (0.06 wt%) was achieved in this work, which was attributed to the selective localization of the CNTs at the blend interface.