Influence of Carbon Nanotubes Purity on the Properties of Carbon Nanotubes/Low-Density Polyethylene Composites

The influence of carbon nanotubes (CNTs) purity on the viscosity, thermal properties, impedance characteristics, and conductivity of CNT/low-density polyethylene (LDPE) nanocomposites was investigated. Two grades of CNT of similar aspect ratios but with different levels of carbon purities were investigated. CNTs with 90% (CNT90) and 95% (CNT95) carbon purity were used. The impedance analysis showed a lower electrical percolation threshold (EPT) of the CNT90/LDPE compared to the CNT95/LDPE. Also, at the same nanofiller loading, the characteristic frequency (fc) of the CNT90/LDPE composites was higher than that of the CNT95/LDPE composites. For example, at 7 wt% CNT, the fc of the CNT90/LDPE and CNT95/LDPE composites were 102 and 1.0 Hz, respectively. This finding reveals better dispersion of the CNT90 compared to the CNT95 in the LDPE. The better dispersion of CNT90 compared to CNT95 in the LDPE is supported by the processing behavior analysis that showed higher viscosity and mixing torque for the CNT90/LDPE composites compared to the CNT95/LDPE composites.