Polyaniline coated cellulose fiber / polyvinyl alcohol composites with high dielectric permittivity and low percolation threshold

Abstract

Cost effective, high performance dielectric composites based on polyvinyl alcohol, cellulose fibers and polyaniline were prepared and the dielectric properties were studied as a function of fiber content, fiber dimensions and polyaniline content over a frequency range of 40 Hz to 30 MHz. The short cellulose fibers were size-reduced to micro and nano levels prior to coating with polyaniline. Fiber surface was coated with Polyaniline (PANI) by an in situ polymerization technique in aqueous medium. The composites were then prepared by solution casting method. Short cellulose fiber composites showed a dielectric constant (DEC) of 2.3 x 105 at 40 Hz. For the micro- and nano- cellulose fiber composites the DEC was increased to 4.5 x 105 and 1.3 x 108, respectively. To gain insight into the inflection point of the dielectric data polynomial regression analysis was carried out. The loss tangent of all the composites remained at less than 1.5. Further, AC conductivity, real and imaginary electric moduli of all the composites were evaluated. PVA nanocomposite attained an AC conductivity of 3 S/m. These showed that by controlling the size of the fiber used, it was possible to tune the permittivity and dielectric loss to desired values over a wide range. These novel nanocomposites, combining high dielectric constant and low dielectric loss, can be effectively used in applications such as high-charge storage capacitors.

Polyaniline-modified nanocellulose prepared from Semantan bamboo by chemical polymerization: preparation and characterization

“…It was found that on increasing the amount of monomer and PANi percentage in the nanocomposite, the average diameter of the resulting particles increased. 31 This might be due to the fact that for higher amount of monomer, the polymerization becomes more intensive, which results in agglomeration in some parts of the nanocomposite (Fig. 4f and h).…”

Flexible high dielectric thin films based on cellulose nanofibrils and acid oxidized multi-walled carbon nanotubes

“…It is ascribed to the electrode effect and Maxwell-Wagner-Sillars interfacial polarization. 24,31,[42][43][44] When an electric eld is applied on the nanocomposite lm, many dipoles and charge carriers accumulate at the interface between the electrode and the sample and between the llers and matrices. With the frequency going up, the high periodic reversal of the electric eld makes it harder for the dipoles and charge carriers to catch up with the change of frequency.…”

“…Commonly used llers for nanocellulose based high dielectrics are ceramic llers (e.g., barium titanate, 12 titanate dioxide 13 ) and conductive llers (e.g., silver nanowires, 3,14 graphene, [15][16][17][18] triglycine sulfate (TGS), [19][20][21][22] polyaniline (PANI), 23,24 carbon nanotubes 25 ). High dielectric nanocellulose/ceramic composites usually demand high ller loading (>50 wt%), leading to severe agglomerations, poor mechanical properties, and low breakdown strength.…”

Polythiophene Coated Cellulosic Fibers from Banana Stem for Improved Electrical, Mechanical, Thermal and Dielectric Properties of Polypropylene Composites

“…Razak et al [18] prepared composites of epoxy resin and polyaniline coated cellulosic fibers from kenafbast. Polyvinyl alcohol was used to prepare composites of polyaniline coated cellulosic fiber composites with low percolation threshold [19].…”