多壁碳纳米管/聚乙烯复合材料的制备及其导电行为

多壁碳纳米管/聚乙烯复合材料的制备及其导电行为;碳纳米管;高密度聚乙烯;渗流阈值;导电行为;V-PTC特性

Preparation and Electrical Properties of Multiwalled Carbon Nanotubes Filled High-density Polyethylene Composites

Multiwalled carbon nanotubes(MWNTs) filled high-density polyethylene (HDPE) composites were prepared by melt blending. Electrical properties, especially the resistivity-temperature characteristics of the composites, were investigated. The results show that the composites filled with MWNTs have a perfect conductivity and the electrical percolation threshold is about 1%-2% (mass fraction). A special resistivity-temperature characteristic,"V-PTC"characteristic, was found, which exhibited that when the mass fraction of MWNTs exceeded the electrial percolation threshold, the resistivity of the composites first decreased ( NTC effect) as the temperature increased, while it increased abruptly when the temperature approached melting point( Tm) of the matrix( PTC effect) . It should be noted that this phenomenon has not been found in polymer-based composites filled with other conductive particles, such as carbon black, graphite, carbon fiber, and so on. This V-PTC characteristic is due to the expanding of the matrix volume and the relaxation of the MWNTs entanglement. Maleic anhydride grafted styrene-(ethylene-co-butylene)-sryrene copolymer(MA-g-SEBS) acts as a compatibilizer to MWNTs and HDPE, which improves the interaction between filler and polymer matrix, and thus almostly eliminated the V-PTC characteristic through restricting the movement of the filler.