Effect of multi-walled carbon nanotubes aspect ratio and temperature on the dielectric behavior of alternating alkene-carbon monoxide polyketone nanocomposites

Abstract New alternating poly(propylene- alt -carbon monoxide/ethylene- alt -carbon monoxide) (PECO)/multiwalled carbon nanotubes (MWCNTs) composites have been prepared. Dielectric permittivity, electric modulus and ac conductivity of the isolated materials were investigated as a function of fiber aspect ratio, frequency and temperature. For aspect ratio of 30 and 200, a transition from insulator to semiconductor was observed at frequency 1×10 4 . However, for high aspect ratio sample (660), no transition was observed and the conductivity is frequency independent in the measured frequency range of 10–10 6  Hz. The conductivity increases from about 1×10 −4 for the sample that contain fibers of aspect ratio 30 and reaches 5×10 −2 (Ω m) −1 for aspect ratio was 660. This behavior can be modeled by a circuit that consists of a contact resistance in series with a parallel combination of resistance ( R ) and capacitance ( C ). The calculated activation energy for sample filled with fibers having aspect ratio 30 is about 0.26 eV and decreases to about 0.16 eV when the aspect ratio is 660.