Rheological and Electrical Percolation Thresholds of Carbon Nanotube/Polymer Nanocomposites

摘要

Percolation thresholds of multiwalled carbon nano-tube/polystyrene (MWCNT/PS) nanocomposites (NC) were determined by rheology and electrical conductivity. The percolation threshold found by electrical conductivity was 0.5% carbon nanotubes (CNT) and that by mechanical spectroscopy and relaxation measurements was 0.9% CNT. These results together with those reported in the literature show several types of percolation thresholds, depending on the average filler-filler (CNT and/or aggregates) distance in a polymer matrix. A distance close to polymer gyration radius corresponds to a 'soft' rheological threshold (P_(c rheo)~(soft) ). Close contacts between fillers giving rise to a conductive path corresponds to an electrical threshold (P_(c elec))- At high filler concentration, fillers form a network, corresponding to a 'rigid' rheological threshold (P_(c rheo)~(rigid))-These thresholds depend on the filler content and follow the order: P_(c elec)~(soft)< P_(c elec < P_(c rheo)~(rigid).