Preparation and Tube Shortening Effects of Multi-walled Carbon Nanotubes on Electrical and Mechanical properties of Polycarbonate/MWCNT Composites

摘要

The effect of nanotube preparation method (freeze drying (FD) vs. oven drying (OD) during synthesis) and length of three multi-walled carbon nanotubes (MWCNTs) on the dispersion and further on the percolation and mechanical behavior of polycarbonate (PC)/MWCNTs composites was investigated. Nanocomposites were melt mixed in a twin-screw micro-compounder at concentration of 0.1-3.0 wt% MWCNTs. Tensile strength was independent of MWCNT concentration while the Young's modulus slightly increases and strain at break appreciable decreases when compare with pure PC. Scanning electron microscopy (SEM) and light microscopy (LM) micrographs revealed that at sub-micron scale shorter MWCNTs were found to be better dispersed than longer tubes, while at the macro scale the dispersion of long and short MWCNTs was comparable. Also, MWCNTs prepared by oven drying methods were found to be better dispersed at the sub-micron scale. Nanotubes with longer lengths (or aspect ratio (AR)) exhibited higher percolation thresholds (pcS) irrespective of differences in dispersion.