Composites of Polycarbonate with Multiwalled Carbon Nanotubes Produced by Melt Mixing

摘要

Composites of polycarbonate (PC) with varying amount of multiwalled carbon nanotubes (MWNT) were prepared by diluting a PC based masterbatch containing 15 wt% MWNT using melt mixing technique. Electrical resistivity data showed percolation of MWNT between 1 and 1.5 wt%. Near the percolation threshold longer mixing at low rotation speed seems to be favorable. The formation of network-like structures also could be detected by oscillatory rheometry and visual observations of the composite dispersions in a PC-solvent. Transmission electron microscopy and atomic force microscopy were used to characterize the state of MWNT dispersion and indicated no pronounced orientation in extrusion direction. The mechanical reinforcement aspect of MWNT is also regarded in context with the masterbatch diluting technology. It was found that molecular weight reduction of PC takes place due to the high shear forces in presence of nanotubes during the masterbatch preparation. This leads to changes in glass transition temperature and counteracts the effects originating from the nanotube addition.