Conductive nylon-MXD6 composites prepared by melt compounding associated with formation of carbon black-covered PET domains serving as big conductive particles

Abstract

This contribution reports an economic yet scientifically-sound approach for the preparation of conductive nylon-poly(m-xylene adipamide) (MXD6) on the basis of a two-level percolation mechanism through addition of poly(ethylene terephthalate) (PET) and carbon black (CB). The primary percolation is percolation of CB in the surfaces of PET domains, and the secondary percolation involves formation of conductive network by highly conductive CB-covered PET domains serving as big conductive particles and CB aggregates in the matrix phase acting as bridges. When 20 wt% of MXD6 was replaced by PET, the percolation threshold of CB dramatically decreased by 83%, resolving the main problem encountered in the preparation of conductive nylon/CB composites. The thermodynamic driving force for assembly of CB on the surface of PET domains is the formation of Janus-type CB particles during compounding as a result of hydrogen bonding and π-π interactions between CB and the two polymers. The effects of PET content and polyester type on electrical conductivity of the composites were discussed in terms of conduction mechanism and interaction difference of CB with MXD6 and the polyester.