Koppalkar R. Anilkumar

Humidity Sensing Properties of Surface Modified Polyaniline Metal Oxide Composites

Polyaniline- (PANI) praseodymium Oxide (Pr2O3) composites have been synthesized by in situ polymerization method with different weight percentages. The synthesized composites have been characterized by Fourier transform infrared spectroscopy, X-ray diffraction and scanning electron microscopy. The temperature dependent conductivity shows that the conductivity is due to the hopping of polarons and bipolarons. These composites show negative thermal coefficient (α) behavior as a function of temperature, which is characteristic behavior of semiconducting materials. Sensor studies have been carried out by two-probe method and found that the sensitivity increases with increase in % RH. It is noticed that stability increase is due to the presence of Pr2O3 in polyaniline up to 30 wt%. A fast recovery and response time along with high sensitivity make these composites suitable for humidity sensors.

Frequency-Dependent Conductivity and Dielectric Permittivity of Polyaniline/TiO2 Composites

Conducting polyaniline/Titanium di-oxide (PANI/TiO2) composites have been synthesized by insitu deposition technique by placing fine graded TiO2 in polymerization mixture of aniline. The PANI/TiO2 composites have been synthesized with various compositions viz., 10,20,30,40 and 50 wt % of TiO2 in PANI. The ac conductivity was studied in the frequency range 102–106 Hz. It is observed from the ac conductivity studies that the ac conductivity is found to be constant up to 105 Hz and there after it increases steeply which is a characteristic feature of disordered materials. The dielectric behaviour was also investigated in the frequency range 102–106 Hz. It is observed from the dielectric studies that the value of dielectric constant decreases up to 20 wt % and later it increases rapidly up to 50 wt %. Similarly it is also seen that the tan δ values decreases rapidly up to 20 wt % and then increases up to 40 wt %, thereafter slowly increases up to 50 wt %. At higher frequencies these composites exhibit almost zero dielectric loss. The dimensions of TiO2 particles in the matrix have a greater influence on the conductivity values and the observed dielectric values.

Impedance Spectroscopic Studies on Nanometric Polyaniline/CdO Composites

The frequency dependent conductivity and dielectric behavior of PANI/CdO polymer nanocomposites based on polyaniline/CdO with SDBSA have been studied. The formation of nanocomposites and changes in the structural and microstructural properties of the materials were investigated by X-ray diffraction (XRD), FTIR and SEM techniques. The variation of ac conductivity with frequency obeys Jonscher power law except a small deviation in the low frequency region due to electrode polarization effect. The dc conductivity increases with increase in CdO concentration. Studies of dielectric properties at lower frequencies show that the relaxation contribution is superimposed by electrode polarization effect. The appearance of peak for each concentration in the loss tangent suggests the presence of relaxing dipoles in the polymer nanocomposite. On addition of CdO, the peak shifts towards higher frequency side indicating the speed up the relaxation time. Analysis of frequency dependence of dielectric and modulus formalism suggests that the electronic and polymer segmental motions are strongly coupled.

Electrical Conductivity of Polyaniline/NiZnO3 Composites: A Solid State Electrolyte

In situ polymerization of aniline was carried out in the presence of nickel zinc oxide to synthesize polyaniline/NiZnO3 composites (PANI/NiZnO3) by chemical oxidation method. The composites have been synthesized with various compositions (10, 20, 30, 40 and 50 wt%) of nickel zinc oxides in PANI. From the infrared spectroscopy (FTIR) studies on polyaniline/NiZnO3 composites, the peak at 1140 cm−1 is considered to be the measure of the degree of electron delocalization. The surface morphology of these composites was studied with the scanning electron micrograph (SEM). The dc conductivity was studied in the temperature range from 40–160°C and supports the one-dimensional variable range hopping (1DVRH) model proposed by Mott. The results obtained for these composites are of scientific and technological interest.

Thermoelectric Power Factor for Polyaniline/Molybdenum Trioxide Composites

The results of thermoelectric power (TEP), power factor and Seebeck coefficient of conducting polyaniline molybdenum trioxide (PANI/MoO 3 ) composites of different weight percentages (10, 20, 30, 40 and 50wt %) has been reported. The results are supported by the theory of coupled transport equations of heat and electricity in metals. It is observed that even though the Seebeck coefficient decreases with doping, the power factor increases with increase in electrical conductivity. The conductivity results lie between 10 – 5 and 10 – 3 S/cm from 0 wt% to 50wt% of MoO3 in PANI respectively match with that of conventional semiconductors.

Influence of Ta2O5 on polyaniline surface for liquid petroleum gas sensing applications

Purpose – The purpose of this paper is to study the sensitivity and selectivity properties of polyaniline/tantalum pentoxide (PANI/Ta2O5) composite to liquid petroleum gas (LPG).Design/methodology/approach – Polyaniline/tantalum pentaoxide (PANI/Ta2O5) composites were synthesized by in situ chemical polymerization method using ammonium persulphate as an oxidizing agent. This is the novel polymerization process for the direct synthesis of emeraldine salt phase of the polymer. The composites were characterized by FTIR, XRD and SEM. Temperature dependence conductivity of the composites shows thermally activated behaviour. Sensitivity and selectivity of the composites are studied.Findings – The PANI/ Ta2O5 composites of 20 wt% and 30 wt% are showing maximum change in resistance against time when compared to pure PANI and other polyaniline composites when exposed to LPG. The 20 wt % composites show maximum sensitivity of 83% to LPG. The selectivity studies reveals that LPG could be sensed better when compared ...

Synthesis and Characterization of Elongated Chain-like Nanostructure Polyaniline in Ice Cube

Highly crystalline polyaniline (PANI) with elongated chain-like nanostructures 20–35 nm in diameter and 60–80 nm in length were prepared using sodium dodecylbenzenesulfonic acid (SDBSA) in ice medium without stirring. The synthesized polyanilines were characterized by SEM, FTIR, and UV-Visible spectroscopy and XRD measurements. The formation of polyaniline/SDBSA salts insoluble in reaction system without stirring is found to be favourable for the formation of this clustered chain-like nanostructure. The temperature dependent conductivity measurement shows a thermally activated exponential behaviour of the chain-like polyaniline nanostructure. The melting point of the nanostructured polyaniline was found to be 253 °C.

Design of sensor setup and study of humidity sensing behaviour of conducting polyaniline / ceramic composites

Sensor setup for the measurement of humidity was designed using square glass chamber provided with sample holder, vaporizer, hygrometer and temperature display. Using this set up, authors have studied the response time of the sensor setup and humidity sensing properties for Polyaniline (PANI) and PANI/sodium metavanadate (NaVO3) composites. The variation in electrical resistance with change in relative humidity (RH) in the range between 20 to 95% of RH is reported and this may be due to change in surface electrical resistance. The variation in resistance and hence conductivity depends on capillary condensation of water causing ionic conductivity within the sensing materials.