AC-ELECTRICAL CONDUCTIVITY AND DIELECTRIC PROPERTIES BEHAVIOUR OF MWCNT/ABS NANOCOMPOSITE

Abba Alhaji Bala 1 , Abdussalam Balarabe Suleiman 1 , Mukhtar Lawan Adam 2 and Ibrahim Saadu 1 . 1. Department of Physics, Federal University Dutse, P.M.B.7156 Jigawa State Nigeria. 2. Department of Physics, Bayero University Kano, P.M.B. 3011 Kano State Nigeria. ...................................................................................................................... Manuscript Info Abstract ......................... ........................................................................ Manuscript History

Since the discovery of carbon isomers for electronics devices application, a number of research works have been carried out with a remarkable and satisfactory result. Carbon nanotubes are new class of carbon isomers which are categorized into single wall nanotube, multi wall nanotube and their ropes or bundles (El-Nahass et al. 2016; Kaneto et al. 1999).
MultiWalled Carbon Nanotubes (MWCNTs) have probe excellently due to their thermal, electrical and mechanical properties. MWCNTs are influential additive to enhance polymer and also an additive to reinforced electrical conductivity in polymer insulation such as polycarbonate (PC), polypropylene (PP), polyethylene (PE) and polymethyl methacrylate (PMMA). The aspect ratio of carbon nanotube when used as conduction nanofiller provides a room for the formation of electric conduction array in the insulating polymer domain at low concentration of nanofiller ( Dielectric materials become a great subject to study electrical behavior of materials which their application is found to be in industrial devices like microwave filters, dynamic access memory telecommunication and voltage controlled oscillators (Kabir et  This polymer material possesses vital characteristics which include electric conductance and polarization that brought to useful effects on dielectric properties. The two kinds of systems for dielectric polarization are charge carriers and dipole systems in which a range of relaxation process together with their metal-insulator, electrodeelectrolyte, semiconductor-insulator and similar kind systems interfacial phases (Ramani et al. 2015).
AC conductivity, σ ac , give information concerning internal structure of materials at relatively low conducting region, it also differentiate between free band conduction where σ ac decreases with increasing frequency and localized conduction in which σ ac increases with increase in frequency (Abd EL-Rahman et al. 2016). AC conductivity measurements have been widely in application to investigate the ionic motion nature in ionically conducting substances because it is assumed that it is responsible for this kind of conduction. It is also well known that, the electrical behavior of ionically complex conducting materials with respect to frequency generate two domains of behavior namely; nearly constant loss (NCL) in which dielectric loss is almost constant and universal dielectric response (UDR). The ac conductivity dependence on frequency, σ ac (ω), obeys the power law equation defined as the UDR given in Eqn. EXPERIMENT DETAILS:-Materials: -ABS; Acrylonitrile-Butadiene-Styrene, (Cycolac Ex-39, Specific gravity 1.03, and MFI 1g/10min) was obtained from SABIC Innovation Plastics. NC7000 was Carbon Nanotubes used in this study which is provided by Nanocyl S.A., Belgium. From the manufacturers, the carbon nanotube is multiwall-made using chemical vapor deposition method (CVD) with an average diameter of 9.5nm and length of 1.5mm.
Composite Preparation:-Before mixing of the nanocomposites, the filler and the polymers were dried up under vacuum for 12 hours at 130 o C and 80 o C respectively, after then the nanocomposite preparation of MWCNT/ABS was carried out by mix-melting in a batch mixer from Thermo Scientific, Germany, by which the nanocomposite was filled with 0wt%, 0.75wt%, 1wt% and 2wt% MWCNT.
The compounding was taking at 50 rpm, 210 o C for 12mm; 9 min for polymer mix with filler melting and 3 min for pure polymer melting. During melt compounding, an increase in viscosity is observed with nanofiller loading as also showed by El-Ghanem et al. 2013. The plates were compressed for ac measurement using Carver compression mold obtained from Carver Inc. USA, to have plates of thickness 1.1mm which were then annealed at 220 o C, 25 MPa pressure for 10 min in the molder.
Results Analysis:-AC Properties Measurement: Impedance: -An impedance is a complex number that consists of two parts; real part (Z') and the imaginary part (Z'') as in equation 2. Z = Z' + jZ'' (2) Where the real part is the resistance, the imaginary part is the loss factor or the reactance and j = √-1 1362 Figure 1 indicated a characteristic behavior of an insulator for which Z' decrease with an increase in frequency for the nanocomposite with filler concentration below the threshold frequency and unfilled ABS. The figure also shows a transition of Z' on frequency, whereas nanocomposite transition behavior is observe to be from frequency independent (Resistive) to frequency dependent (Capacitive) and the cut-off frequency increases with concentration of MWCNT as also indicated in another study (Al-Saleh et al. 2013). The dielectric curve vs. frequency (Fig. 3) shows no peaks as the curve is smoothing slippery compared to figure 3, this is due to the fact that, there are two losses type of dielectric. The first is due to the flow of the real charge into the dielectric called conduction loss and the second is due to the rotation of molecules/atoms in the alternating current field called dielectric loss. As a result of this, the MWCNT/ABS composite conduction is dominance at low frequency by resistance, as such, much conduction loss is produced. The production of this loss give rise to the sample temperature in the ac field and causes a disorder in the motion of the charge carriers that breaks the regular arrangement slowly at the composite interface as shown in figure

AC Electrical Conductivity: -
The ac electrical conductivity dependence on frequency for MWCNT/ABS composite is shown in figure 6. It is evident from the figure that the conductivity increases with frequency increase. This is due to the ac electrical conductivity characteristics of CNT which solemnly depend on CNT content in the composite. The conductivity increase with increasing CNT content, whereas, the highest conductivity was found with 1% concentration which may be due to partial substitution of CNT, similar was also found by Rahman

Conclusion:-
AC-Electrical conductivity and dielectric properties of MultiWalled Carbon Nanotube-Acrylonitrile Butadiene Styrene composite (MWCNT/ABS) has been investigated. The conductivity increases with increasing CNT content and frequency increase due to the ac electrical conductivity characteristics of CNT which solemnly depend on CNT content in the composite. The study also showed that electrical conductivity σ, obeys the power law σ ac = Aω S with the frequency exponential factor S < 1 that indicate ε'' not equal to constant and depends on frequency. The dielectric constant ε' and dielectric loss ε'' remain constant with increase in frequency at lower concentration of CNT but shows increase in frequency with decrease of ε' and ε'' at high concentration which indicated that high concentration CNT play a vital role in increasing dielectric constant and dielectric loss