Effects of Molecular Weight and Annealing on Electrical Conductivity of Multi-Walled Carbon Nanotube/Polypropylene Composites
Composites of polypropylene (PP) and multi-walled carbon nanotubes (MWCNTs) were prepared by a micro melt mixing process. The molecular weight of PP was varied from 190,000 to 340,000 to examine its effects on the electrical conductivity. It has been discovered that a significant enhancement of electrical conductivity could be achieved by a thermal post annealing process above the melting temperature of PP. Factors such as annealing time, temperature, viscosity of PP, and content of MWCNTs all affected the enhancement of electrical conductivity. Re-aggregation of MWCNTs and the subsequent formation of MWCNT networks during annealing are considered to be the main reasons for the quick enhancement of electrical conductivity. The observed effect of molecular weight of PP on the enhancement of electrical conductivity suggested that the enhancement process could be controlled by diffusion of MWCNTs.
Jianhong Zhao, Masanori Kunieda, Guilin Yang and Xue-Ming Yuan
Y. Z. Pan et al., "Effects of Molecular Weight and Annealing on Electrical Conductivity of Multi-Walled Carbon Nanotube/Polypropylene Composites", Key Engineering Materials, Vols. 447-448, pp. 619-623, 2010