Comparative study of multiwalled carbon nanotube/polyethylene composites produced via different techniques

A comparative study of multiwalled carbon nanotube/polyethylene (MWCNT/PE) composites produced by different methods (thermal mechanical mixing, coagulation precipitation technique and in situ ethylene polymerization with a Ziegler–Natta catalyst supported on MWCNTs) has been performed. The morphology and structure of the produced composites were investigated by optical, scanning and transmission electron microscopies. MWCNT incorporation into PE matrix results in the change of conductivity mechanism from conductivity typical of a system with local disorder and effects of weak interaction of electrons (quantum correction to conductivity) to conductivity that can be described within the theory of Coulomb blockade or quasi-one-dimensional variable-range hopping conductivity with variable length of hops (Mott's law) between localized states. The electromagnetic (EM) response of composites was investigated in a broadband region (118–510 GHz). It was found that the dielectric properties of MWCNT/PE composites correlate with their electrophysical properties determined by the MWCNT distribution within the polymer matrix. Typical TEM image of MWCNT in polyethylene matrix. Distance between nanotubes filled with PE varies within a wide range