Dispersion, agglomeration, and network formation of multiwalled carbon nanotubes in polycarbonate melts
Sven Pegel¹, Petra Potschke¹, Gudrun Petzold¹, Ingo Alig², Sergej M. Dudkin², Dirk Lellinger²; Article in Press Polymer (2008), doi:10.1016/j.polymer.2007.12.024.
Abstract: Three different industrially available multiwalled carbon nanotube (MWNT) materials were directly incorporated into polycarbonate by melt mixing using a small-scale compounder. Despite of similar aspect ratios the electrical percolation behaviour was different. TEM investigations reveal significant differences in the nanotube dispersion which can be attributed to different dispersability of the raw MWNT materials. It is shown that the investigation of the sedimentation behaviour of aqueous MWNT dispersions is a simple method to gain this material characteristic. The relationships between melt processing conditions and MWNT dispersion and distribution were studied on polycarbonate samples containing 0.875 wt% MWNT prepared by masterbatch dilution. During melt mixing only high shear forces can provide suitable MWNT dispersion because firstly the MWNT disentanglement is facilitated and secondly secondary agglomeration is prevented. At low shear agglomeration of formerly well dispersed MWNT could be observed. During hot pressing the network or MWNTarrangement and the resulting electrical conductivity can be manipulated by the processing conditions like melt temperature and pressing speed. A certain nanotube agglomeration can enhance the development of an electrical percolated network as shown by dielectric spectroscopy..
Key words: Multiwalled carbon nanotubes • Polycarbonate melts • Nanotube dispersions • Network formation • Sedimentation • Stability • Disentanglement • Electrical conductivity • LUMiFuge
¹ Leibniz-Institut fur Polymerforschung Dresden e.V., Hohe Straße 6, 01069 Dresden, Germany; ² Deutsches Kunststoff-Institut, Schloßgartenstraße 6, 64289 Darmstadt, Germany.Contact us
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