A strategy for achieving low percolation and high electrical conductivity in melt-blended polycarbonate (PC)/multiwall carbon nanotube (MWCNT) nanocomposites: Electrical and thermo-mechanical properties

Abstract

Abstract. In this work, polycarbonate (PC)/multiwall carbon nanotube (MWCNT) nanocomposites were prepared by simple melt mixing at a temperature (~350°C) well above the processing temperature of PC, followed by compression molding, that exhibited percolation threshold as low as of 0.11 wt% and high electrical conductivity of 1.38!10 -3 S·cm -1 at only 0.5 wt% MWCNT loading. Due to the lower interfacial energy between MWCNT and PC, the carbon nanotubes are excellently dispersed and formed continuous conductive network structure throughout the host polymer. AC electrical conductivity and dielectric permittivity of PC/MWCNT nanocomposites were characterized in a broad frequency range, 10 1 -10 7 Hz. Low percolation threshold (p c ) of 0.11 wt% and the critical exponent (t) of ~3.38 was resulted from scaling law equation. The linear plot of log! DC vs. p -1/3 supported the presence of tunneling conduction among MWCNTs. The thermal property and storage modulus of PC were increased with the incorporation of little amount of MWCNTs. Transmission electron microscopy (TEM) and field emission scanning electron microscopy (FESEM) confirmed the homogeneous dispersion and distribution of MWCNTs throughout the matrix phase.

Dielectric spectroscopy of high aspect ratio graphene-polyurethane nanocomposites

“…At higher frequencies, charge carriers due to the excitations hop around the nearby conductive sites back and forth causing an increase in the effective conductivity. [25] At high temperatures, the AC conductivity behavior is distinctive. It can be explained via activation energy equation.…”

“…Capacitance and dielectric tangent loss were observed directly, while dielectric constant, dielectric loss, and AC conductivity were derived as under. [25] The complex permittivity is represented as (1) where the real part ε' gives the dielectric constant and the imaginary part depicts the dielectric loss. Dielectric constant, a quantity measuring the ability of a substance to store electrical energy in an electric field, can be calculated by using the following equation (2) where C is the observed capacitance of the sample, d is the thickness, A is the area, and ε 0 is the permittivity of free space.…”

Carbon nanofillers incorporated electrically conducting poly ε-caprolactone nanocomposite films and their biocompatibility studies using MG-63 cell line

“…Insulating polymers can be modified to conducting nanocomposites amidst retaining the polymer properties using conducting nanofillers. The continuous conducting network formation using conducting nanofillers can only be achieved above some critical amount of nanofiller loading (percolation threshold) [16]. To achieve percolated network at low nanofiller concentration with appreciable reproducibility, the conductivity of the nanofillers and its aspect ratio should be very high [17].…”

Tough semiconductor polycarbonate/multiwalled carbon nanotubes nanocomposites by rubber modification

“…Moreover, electrically conductive NCs based on PC can be obtained at low MWCNT contents (0.1-2 %) by direct melt processing of both components [17,18], or by using previously prepared highly dispersed PC master-batches [19,20]. The presence of 4 relatively low MWCNT contents (2-3 %) seriously deteriorates the ductility of the PC matrix, which shows a dangerous tough/brittle transition at around these contents [21,22].…”