Effects of multiwalled carbon nanotube mass fraction on microstructures and electrical resistivity of polycarbonate-based conductive composites

Abstract

Four polycarbonate (PC)-based composites with 1, 2.5, 5, and 10 wt.% raw multiwalled carbon nanotubes (MWCNTs) were prepared using extrusion process followed by injection molding. The effects of MWCNT mass fraction (W) on composite mechanical, thermal, and electrical properties were examined. The mechanical properties suggested that the tensile strength of the composites with 2.5 wt.% raw MWCNTs exhibited an increase of ~5 MPa (~8.6%) at a particular injection condition. Besides, thermogravimetric analysis (TGA) indicated that the addition of 1 wt.% MWCNTs improved the thermal stability of PC by approximately 100°C. Aside from mechanical and thermal properties, the electrical resistivity of the 5 wt.% raw MWCNT composites was considerably decreased to 102 Ω/sq, a value approximately 15 orders of magnitude lower than that of PC. Furthermore, the effects of injection conditions on composite electrical properties were emphatically discussed, and it was found that electrical resistivity was sensitive to injection temperature and speed. Low electrical resistivity was achieved at high injection temperature and low injection speed. Scanning electron microscopy images revealed that electrical resistivity relied on the microstructure of the prepared MWCNT/PC composites.

Keywords

• carbon nanotubes
• electrical resistivity
• injection condition
• microstructure
• polycarbonate