Broadband electrical conductivity of metal/carbon nanotubes polyamide 6 composites fabricated by reactive encapsulation

Abstract

This is the first broadband dielectric spectroscopy study on the temperature- and frequency-dependent electrical conductivity of polyamide 6 (PA6) composites containing both metal microparticles (Al, Fe, or Cu) and carbon nanotubes (CNT). The dually reinforced PA6 hybrids are prepared through compression molding of metal- and CNT-loaded microparticles (MP). These MP are synthesized by activated anionic ring-opening polymerization (AAROP) of ε-caprolactam in suspension, carried out in the presence of the micron-sized metal powders and the nanosized CNT fillers, with a combined load of up to 10 wt%. The good dispersion of the two loads by the AAROP strategy results in a notable increase in the electrical conductivity by up to 11 orders of magnitude. Moreover, the frequency-dependent behavior of the measured conductivity obeys the so-called universal dynamic response. This response involves a direct current (d.c.) electrical conductivity ($${\sigma }_{{\text{dc}}}$$ σ dc ) observed beyond a critical frequency, $${F}_{{\text{c}}}$$ F c , followed by a power-law response characterized by an exponent s, which fluctuates between 0.11 and 0.43. The $${\sigma }_{{\text{dc}}}$$ σ dc of the binary composites spans from 1.42 $$\times$$ × 10−5 to 1.63 $$\times$$ × 10−2 S/cm, this increase being attributed to the synergetic effect between CNT and the metal particles that contribute to the carrier mobility within the conductive network. Graphical Abstract

Synergistic Effect of Aluminum Nitride and Carbon Nanotube-Reinforced Silicon Rubber Nanocomposites

“…To address the deficiency of single filler-incorporated polymer composites, a synergistic effect based on hybrid fillers was developed for the construction of high-performance composites [ 16 , 17 , 18 , 19 , 20 , 21 , 22 ]. The hybrid filler system can accelerate the construction of a continuous filler structure and upgrade the dispersion/exfoliation of each filler.…”