M.F. Shukur

Conductivity and electrical properties of corn starch–chitosan blend biopolymer electrolyte incorporated with ammonium iodide

This work focuses on the characteristics of polymer blend electrolytes based on corn starch and chitosan doped with ammonium iodide (NH4I). The electrolytes were prepared using the solution cast method. A polymer blend comprising 80wt% starch and 20wt% chitosan was found to be the most amorphous blend and suitable to serve as the polymer host. Fourier transform infrared spectroscopy analysis proved the interaction between starch, chitosan and NH4I. The highest room temperature conductivity of (3.04±0.32)◊10 4 Scm 1 was obtained when the polymer host was doped with 40wt% NH4I. This result was further proven by field emission scanning electron microscopy study. All electrolytes were found to obey the Arrhenius rule. Dielectric studies confirm that the electrolytes obeyed non-Debye behavior. The temperature dependence of the power law exponent s for the highest conducting sample follows the quantum mechanical tunneling model.

Conductivity and transport studies of plasticized chitosan-based proton conducting biopolymer electrolytes

This paper focuses on the conductivity and transport properties of chitosan-based solid biopolymer electrolytes containing ammonium thiocyanate (NH4SCN). The sample containing 40 wt% NH4SCN exhibited the highest conductivity value of (1.81 ± 0.50) × 10−4 S cm−1 at room temperature. Conductivity has increased to (1.51 ± 0.12) × 10−3 S cm−1 with the addition of 25 wt% glycerol. The temperature dependence of conductivity for both salted and plasticized systems obeyed the Arrhenius rule. The activation energy (Ea) was calculated for both systems and it is found that the sample with 40 wt% NH4SCN in the salted system obtained an Ea value of 0.148 eV and that for the sample containing 25 wt% glycerol in the plasticized system is 0.139 eV. From the Fourier transform infrared studies, carboxamide and amine bands shifted to lower wavenumbers, indicating that chitosan has interacted with NH4SCN salt. Changes in the C–O stretching vibration band intensity are observed at 1067 cm−1 with the addition of glycerol. The Rice and Roth model was used to explain the transport properties of the salted and plasticized systems.

Protonic Transport Analysis of Starch-Chitosan Blend Based Electrolytes and Application in Electrochemical Device

Two polymer electrolyte systems (unplasticized and plasticized) based on starch-chitosan blend doped with ammonium bromide (NH4Br) were prepared. The conductivity was found to be influenced by the number density (n) and mobility (μ) of the ions. The highest conducting plasticized electrolyte had n and μ values of 8.75 × 1018 cm−3 and 1.03 × 10−3 cm2 V−1 s−1, respectively. Ionic transference number for the highest conducting plasticized electrolyte was found to be 0.92. An electrochemical double layer capacitor (EDLC) using the highest conducting plasticized electrolyte was cycled for 500 times at 0.048 mA cm−2.

Conductivity studies of biopolymer electrolytes based on chitosan incorporated with NH4Br

A polymer electrolyte system based on chitosan complexed with ammonium bromide (NH4Br) salt was prepared by the solution cast technique. 30 wt% NH4Br added electrolyte gave a room temperature conductivity of (4.38 ± 1.26) × 10−7 S cm−1 and increased to (2.15 ± 0.47) × 10−4 S cm−1 with addition of 40 wt% glycerol. The dependence of the conductivity on temperature proves that both chitosan–NH4Br and chitosan–NH4Br–glycerol systems are Arrhenian. The activation energy (Ea) value for 70 wt% chitosan–30 wt% NH4Br film is 0.31 eV and the Ea value for 42 wt% chitosan–18 wt% NH4Br–40 wt% glycerol film is 0.20 eV. The carboxamide band at 1640 cm−1 and the amine band at 1549 cm−1 in the spectrum of pure chitosan film shifted to 1617 and 1516 cm−1, respectively, in the spectrum of 70 wt% chitosan–30 wt% NH4Br film, indicating the occurrence of complexation between polymer and salt. The band at 1024 cm−1 in the pure chitosan film spectrum, which corresponds to the C–O stretching vibration, shifted to lower wavenumbers on addition of salt. A new band appears at 997 cm−1 on addition of 40 wt% glycerol.

Electrical Properties of Starch Based Silver Ion Conducting Solid Biopolymer Electrolyte

In the present study, the electrical and dielectric properties of a solid biopolymer electrolyte system based on starch doped with different amounts of silver nitrate (AgNO3) were analyzed. The electrolyte system was prepared via solution cast technique. Electrical impedance spectroscopy (EIS) measurement for the system was conducted over a frequency range of 50 Hz - 1 MHz at room temperature. It was found that the sample containing 6 wt.% AgNO3 obtained the highest conductivity value of 1.03 × 10-9 S cm-1. The effect of salt concentration on the dielectric properties of the electrolytes was also studied in relation to the conductivity properties. The dielectric studies indicated that the electrolytes in the present study obeyed non-Debye behavior.

Transport Properties of Chitosan/Peo Blend Based Proton Conducting Polymer Electrolyte

The polymer electrolytes were prepared using the solution cast technique. The polymer host consisted of chitosan and poly(ethylene oxide) (PEO). Ammonium nitrate (NH4NO3) was added to the blend solution to provide the charge carriers for ionic conduction. The sample containing 40 wt.% NH4NO3 exhibited a conductivity value of 5.83 × 10-4 S cm-1 at 373 K. Conductivity-temperature relationship for all samples obeyed Arrhenius rule and the activation energy of each samples were obtained. The sample containing 40 wt.% NH4NO3 showed the lowest activation energy at 0.29 eV. The conductivity variation for the prepared electrolyte system was explained using the Rice and Roth model. Sample with 40 wt. % NH4NO3 exhibited the highest number density and mobility of charge carriers with values of 1.39 × 1020 cm-3 and 4.60 × 10-6 cm2 V-1 s-1 respectively. The increase in conductivity was attributed to the increase in the number density and mobility of charge carriers.

Dielectric Studies of Proton Conducting Polymer Electrolyte Based on Chitosan/PEO Blend Doped with NH4NO3

Polymer blend of chitosan and poly(ethylene oxide) (PEO) electrolytes were prepared by employing solution cast method. Ammonium nitrate (NH4NO3) was added to the blend to supply the charge carriers for ionic conduction. The impedance of the electrolytes was measured by electrical impedance spectroscopy (EIS) over the frequency range of 50 Hz to 1 MHz. The permittivity ɛr and electric modulus Mr of the complex were analyzed. Dispersion at low frequencies caused by space charge effect from the electrodes was observed. The modulus plots indicated that the dispersion deviated from the Debye behaviour. The relaxation time, τ decreased to 1.64 × 10-7 s as the NH4NO3 content was increased up to 40 wt.%.

Conduction Mechanism and Dielectric Properties of Solid Biopolymer Electrolyte Incorporated with Silver Nitrate

onic conductivity and dielectric properties of starch based polymer electrolytes doped with silver nitrate (AgNO3) at elevated temperatures were studied. The solid polymer electrolytes were prepared using the solution cast method. X-ray diffraction (XRD) analysis implied that the incorporation of 6 wt.% AgNO3 increased the amorphous phase of the electrolyte. Temperature dependence conductivity plots showed that electrolyte containing 6 wt.% AgNO3 obeyed Arrhenius rule with activation energy, Ea of 0.71 eV. The effect of temperature on the dielectric properties of the electrolyte was also studied in relation to the conductivity properties. The variation of dielectric loss with frequency was obtained from the power law exponent. Temperature dependence of the power law exponent concluded that the conduction mechanism of the 94 wt.% starch-6 wt.% AgNO3 electrolyte followed the correlated barrier hopping (CBH) model.