M. Revanasiddappa

Synthesis, characterization and low frequency a.c. conduction of polyaniline/fly ash composites

In situ polymerization of aniline was carried out in the presence of fly ash (FA) to synthesize polyaniline/ fly ash (PANI/FA) composites. The PANI/FA composites have been synthesized with various compositions (15, 20, 30 and 40 wt%) of FA in PANI. The composites, thus synthesized have been characterized by infrared spectroscopy and X-ray diffraction. The morphology of these samples was studied by scanning electron microscopy. Further the a.c. conductivity of these composites have been investigated in the frequency range 102–106 Hz. The presence of polarons and bipolarons are made responsible for frequency dependence of a.c. conductivity in these composites. The Cole-Cole plots indicate clear shift in the distribution of relaxation times as the wt% of FA in PANI changes. These composites show almost symmetric semicircles of Cole-Cole plots indicating the Debye-type relaxation in their polarization response.

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.

Dielectric property of NiTiO3 doped substituted ortho-chloropolyaniline composites

Ortho-chloropolyaniline (OCP)-NiTiO3 composites have been synthesized via in-situ polymerization of ortho-chloroaniline with various weight percentages of NiTiO3. Fourier Transform Infrared spectroscopic studies of Ortho-chloropolyaniline and its composites indicated the formation of composites as a result of Vander Waals interaction between OCP and NiTiO3 particles. Surface morphology of OCP and OCP-NiTiO3 composites were studied using Scanning Electron Microscope (SEM). The SEM micrographs indicated a modified morphology after the composite formation. Dielectric properties and electric modulus of OCP and OCP-NiTiO3 composites have been investigated in the frequency range of 50 Hz – 5 MHz. It has been noticed that electrical resistance decreases with increase in weight percentage of NiTiO3 particles in polymer matrix as well as with applied frequency. The display of semicircular arcs in Cole-Cole plots indicates the formation of series resistor and capacitor in network causing a decrease in the relaxati...

Synthesis, Characterization and Electrical Properties of Polyaniline/BaTiO3 Composites

Conducting polyaniline/BaTiO 3 (PANI/BT) composites have been synthesized by ‘in situ’ deposition technique by placing fine graded BaTiO 3 in polymerization mixture of aniline. The composites are characterized using various techniques such as SEM, XRD and IR spectroscopy. The electrical properties such dc conductivity and ac conductivity are studied by sandwitching the pellets of these composites between the silver electrodes. It is observed that in both the cases the values of conductivities increases up to 30 weight % of BaTiO 3 in polyaniline and decreases thereafter. Initial increment in conductivity is due to extended chain length of polyaniline where polarons possess sufficient energy to hop between favorable sites. Beyond 30 weight % of BaTiO 3 in polyaniline, the blocking of charge carriers takes place reducing the conductivity values. The polyaniline/ BaTiO 3 composites are poled by applying constant voltage for a fixed time to study their electrical hysteresis characteristics. It is observed that the area under the curve depends on the content of BaTiO 3 in polyaniline.

Synthesis of polyaniline/ZrO2 nanocomposites and their performance in AC conductivity and electrochemical supercapacitance

Polyaniline/zirconium oxide (PANI/ZrO2) nanocomposites have been synthesized by incorporating ZrO2 nanoparticles into the PANI matrix via liquid–liquid interfacial polymerization method. The composite formation and structural changes in PANI/ZrO2 nanocomposites were investigated by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR). PXRD pattern of PANI/ZrO2 nanocomposites exhibited sharp and well-defined peaks of monoclinic phase of ZrO2 in PANI matrix. SEM images of the composites showed that ZrO2 nanoparticles were dispersed in the PANI matrix. The FT-IR analysis revealed that there was strong interaction between PANI and ZrO2. AC conductivity and dielectric properties of the nanocomposites were studied in the frequency range, 50–106 Hz. AC conductivity of the nanocomposites obeyed the power law indicating the universal behaviour of disordered media. The nanocomposites showed high dielectric constant in the order of 104, which could be related to dielectric relaxation phenomenon. Further, the materials were checked for their supercapacitance performance by using cyclic voltammetry (CV), chronopotentiometry (CP) and electrochemical impedance spectroscopy (EIS). Among the synthesized nanocomposites, PANI/ZrO2-25 wt.% showed a higher specific capacitance of 341 F g−1 at 2 m Vs−1 and good cyclic stability with capacitance retention of about 88% even after 500 charge–discharge cycles.

Synthetic, Spectral and Thermal Studies of Tin(IV) Complexes of 1, 5-Benzodiazepines

Tin(IV) complexes of 7-substituted 6,7-benzo-1,5-dizepines have been synthesized in absolute alcoholic medium. Elemental analysis indicates that the complexes have 1:2 stoichiometry of the type L2SnCl4, TGA data support this conclusion. Molar conductance values in DMF at 10–3 M suggest that, these complexes are non-electrolytes. Infrared spectral data shows the involvement of C=N and NH groups in coordination with the metal ion. X-ray diffraction pattern of few representative complexes indicate that, these are having simple cubic crystal structure. The energy of activation and order of reaction are calculated using TGA data of the complexes. All these information support that Sn(IV) in these complexes exhibits coordination number eight.

Electromagnetic shielding effectiveness studies on polyaniline/CSA-WO3 composites at KU band frequencies

This paper highlights the Electromagnetic Interference (EMI) Shielding Effectiveness and electromagnetic wave attenuation behavior of Polyaniline/Camphor Sulphonic Acid (PANI-CSA) – tungsten oxide (WO3) composites. Insitu polymerization of aniline monomer with camphor sulphonic acid (CSA) as a dopant was carried out in the presence of ammonium persulphate an oxidizing agent to synthesize PANI-CSA tungsten oxide composites (PANI/CSA-WO3) by chemical oxidation method. The composites have been synthesized with various compositions (10, 20, 30, 40 and 50 wt %) of tungsten oxide in PANI/CSA matrix. The EMI shielding measurements were carried out in the broad microwave spectrum covering the frequency range from 12 to 18 GHz (Ku-Band). The results show the influence of tungsten oxide in PANI/CSA over the EMI shielding Effectiveness. The composites have shown excellent microwave absorption behavior confirmed by the EMI Shielding Effectiveness values of the order of −15 to −16 dB.This paper highlights the Electromagnetic Interference (EMI) Shielding Effectiveness and electromagnetic wave attenuation behavior of Polyaniline/Camphor Sulphonic Acid (PANI-CSA) – tungsten oxide (WO3) composites. Insitu polymerization of aniline monomer with camphor sulphonic acid (CSA) as a dopant was carried out in the presence of ammonium persulphate an oxidizing agent to synthesize PANI-CSA tungsten oxide composites (PANI/CSA-WO3) by chemical oxidation method. The composites have been synthesized with various compositions (10, 20, 30, 40 and 50 wt %) of tungsten oxide in PANI/CSA matrix. The EMI shielding measurements were carried out in the broad microwave spectrum covering the frequency range from 12 to 18 GHz (Ku-Band). The results show the influence of tungsten oxide in PANI/CSA over the EMI shielding Effectiveness. The composites have shown excellent microwave absorption behavior confirmed by the EMI Shielding Effectiveness values of the order of −15 to −16 dB.

Synthesis and characterisation study on polyaniline-SFA-Ag nanocomposite with plasma surface treatment

Abstract In-situ polymerisation of aniline was carried out in the presence of Sintered Fly Ash to synthesise polyaniline-SFA-Ag (IPANI-SFA-Ag) nanocomposite by chemical oxidation method with various compositions (5, 10, 15, 20 and 25 wt %) of fly ash in polyaniline. The synthesised composite film was surface modified by DC glow discharge plasma to improve the surface properties of IPANISFA-Ag nanocomposite. The prepared composite films were characterised by FTIR, XRD, SEM, UV and DC conductivity analysis. From FTIR analysis, some new bonds, like C=O, C-H., were observed in the plasma-treated samples. An XRD analysis report shows that the Ag nanoparticles were in good agreement with IPANI and the intensity of the composite has increased after plasma treatment. The calculated average grain size of the composite was 38 nm; also the specific surface area of both samples was (SSA) 26 m2 g-1.

Synthesis and conductivity study on polyaniline/BaFe/silver (PANI+BaFe+Ag) nanocomposite with plasma treatment

Polyaniline/fly ash/silver (IPANI+BaFe+Ag) composite films were prepared in different concentrations of BaFe and surface modified by DC glow discharge plasma. The prepared composite films were characterised by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), UV and DC conductivity analysis. From FTIR analysis, some new bonds like C = O and C–H were observed in the plasma treated samples. An XRD analysis report shows that the Ag nanoparticles were in good agreement with IPANI, and the intensity of the composite has increased after plasma treatment. The calculated average grain size of untreated Ag is 38 nm and plasma treated is 35 nm, and also, the specific surface area of both samples is 24 m2 g− 1. SEM analysis showed the Ag particles were well distributed on IPANI and also had a small amount of surface roughness after plasma treatment. The UV–Vis absorption spectroscopy indicates the characteristics of absorption spectra of IPANI. The DC conductivity of pure PANI/BaFe+Ag nanocomposites clearly indicated that the Ag nanoparticles increased the electrical conductivity of PANI nanocomposites as compared to pure aniline.