Influence of Carbon Black and Silica Fillers with Different Concentrations on Dielectric Relaxation in Nitrile Butadiene Rubber Investigated by Impedance Spectroscopy

In neat nitrile butadiene rubber (NBR), three relaxation processes were identified by impedance spectroscopy: α and α′ processes and the conduction contribution. We investigated the effects of different carbon black (CB) and silica fillers with varying filler content on the dielectric relaxations in NBR by employing a modified dispersion analysis program that deconvolutes the corresponding processes. The central frequency for the α′ process with increasing high abrasion furnace (HAF) CB filler was gradually upshifted at room temperature, while the addition of silica led to a gradual downshift of the center frequency. The activation energy behavior for the α′ process was different from that for the central frequency. The use of HAF CB led to a rapid increase in DC conductivity, resulting from percolation. The activation energy for the DC conductivity of NBRs with HAF CB decreased with increasing filler, which is consistent with that reported in different groups.

Impedance, Electrical Equivalent Circuit (EEC) Modeling, Structural (FTIR and XRD), Dielectric, and Electric Modulus Study of MC-Based Ion-Conducting Solid Polymer Electrolytes

The polymer electrolyte system of methylcellulose (MC) doped with various sodium bromide (NaBr) salt concentrations is prepared in this study using the solution cast technique. FTIR and XRD were used to identify the structural changes in solid films. Sharp crystalline peaks appeared at the XRD pattern at 40 and 50 wt.% of NaBr salt. The electrical impedance spectroscopy (EIS) study illustrates that the loading of NaBr increases the electrolyte conductivity at room temperature. The DC conductivity of 6.71 × 10−6 S/cm is obtained for the highest conducting electrolyte. The EIS data are fitted with the electrical equivalent circuit (EEC) to determine the impedance parameters of each film. The EEC modeling helps determine the circuit elements, which is decisive from the engineering perspective. The DC conductivity tendency is further established by dielectric analysis. The EIS spectra analysis shows a decrease in bulk resistance, demonstrating free ion carriers and conductivity boost. The dielectric property and relaxation time confirmed the non-Debye behavior of the electrolyte system. An incomplete semicircle further confirms this behavior model in the Argand plot. The distribution of relaxation times is related to the presence of conducting ions in an amorphous structure. Dielectric properties are improved with the addition of NaBr salt. A high value of a dielectric constant is seen at the low frequency region.

STUDY OF AC/DC CONDUCTIVITY OF POLY VINYL CHLORIDE PVC AND EC, EC/PVC CONDUCTION MECHANISMS RESPONSIBLE FOR THE CONDUCTIVITY

The current work investigates the AC and DC conductivity constant of PVC and EC samples (3:1) at many constant temperatures in the frequency range (323K to 363K). The ndings were presented in graph form. The dielectric constant increases with temperature increase at constant frequencies, Dielectric constant decreases with frequency increases, and AC conductivity increases with frequencies at different constant temperatures. The frequencies reach almost saturation values as the ultimate 1MHz value reaches. The AC conductivity increases with the increase in frequency has been observed.

Acrylic Acid (AA) Based Polyaniline Composite for Liquified Petroleum Gas (LPG) Sensors

N-substituted PANI-ES was obtained from N-phenyl-β-alanine (N-substituted aniline). N-phenyl-β-alanine was synthesized chemically from methyl acrylate and aniline precursor. ESI-MS, H1NMR spectroscopy and FTIR spectroscopy are employed to characterise the N-phenyl-β-alanine for structure elucidation. The structure and properties of corresponding polymers were investigated by X-ray diffraction, FTIR, UV-Visible, H1NMR, FESEM, solubility, and DC conductivity. On the basis of experimental results of prepared N-substituted aniline monomer and its corresponding polymer is proposed. At room temperature, the average DC conductivity of as-prepared PANI polymers was found in semiconducting range, which is 0.153 S/cm for poly (3-methyl (phenyl amino) propionic acid. We also were analysed temperature dependent DC conductivity with and without magnetic field of as prepared PANI polymers to understand the conduction mechanism and it was followed variable-range hopping (VRH) process. In addition, we were discussed the response of liquefied petroleum gas (LPG) with polyaniline based sensor materials.

Electrical Conductivity Enhancement of V2O5-P2O5-Bi2O3 Glasses by Nanocrystallization

The structural and electrical properties of the xP2O5-(40 − x) Bi2O3-60V2O5 (0 ≤ x ≤ 20) glass system have been investigated. The samples were prepared by the conventional melt-quenching technique. X-ray diffraction (XRD) patterns confirmed the amorphous nature of the present glasses. Nanocrystalline grains were found due to the annealing of the glass samples under study. Nanocrystals with an average grain size of 22 nm were implanted in the glass structure and estimated from the XRD patterns of the glass–ceramic samples. DC conductivity of the glass system has been determined in the temperature range 300–500 K. It was found that the general behavior of electrical conductivity was similar for all the glass compositions and found to decrease with increasing phosphate content. The electrical conductivity of the glass–ceramic nanocrystals obtained by annealing at crystallization temperature (Tc) was much higher than the initial glass. The activation energy (W) was enhanced by annealing and was obtained from plots of temperature-dependent DC conductivity, and found to be 0.23–0.31 eV for glasses and 0.19–0.23 eV for the glass–ceramic nanocrystals.

Poly Methyl Methacrylate (Pmma) Based Polyaniline Composite for Ammonia (Nh3) Gas Sensors

Inorganic acids (HCl, H2SO4, and H3PO4) doped-PMMA/PANI composites are prepared by in-situ technique via oxidation-polymerization process. Different techniques such as XRD, FTIR, UV-Visible, four-probe method are used to characterize the composite. Presence of different chemical group of the doped composites is analysed by ATR-FTIR spectroscopic analysis. Charge carrier behaviour of the doped composite is analyzed by UV-Visible spectroscopy. Band gap (Eg) of the doped composites is determined from UV-Visible absorption analysis using Tauc expression. The estimated direct band gap energy (Eg) is found to be 1.93 eV (for HCl doped PMMA/PANI composite), 1.19 eV (for H2SO4 doped PMMA/PANI composite), and 1.71 eV (for H3PO4 doped PMMA/PANI composite), respectively. DC-conductivity is measured with and without magnetic field. Temperature dependent DC conductivity is also measured. In addition, we were discussed the response of ammonia (NH3) gas with polyaniline-based sensor materials.

Inorganic Acid Doped Polyaniline Based Carbon Monoxide (Co) Sensor

Simple in situ chemical oxidation method was employed to prepare different molar of HCl doped DL−PLA/PANI composites using AnHCl as precursor. Surface morphology, ATR−FTIR, UV–Visible, and band gap were studied. PANI nanowires with different diameter and smooth surface were observed for composites. The lowest direct band gap was found to be 1.68 eV for 2 (M) HCl doped DL−PLA/PANI. DC conductivity at room temperature was measured and followed the ohmic behaviour. The calculated highest DC conductivity at room temperature was found to be 0.1628 × 10−2 (S/cm) for 2 (M) HCl doped DL−PLA/PANI. Temperature variation (70−300 K) DC conductivity without magnetic field of as prepared composites was analysed using linear four probe techniques and showed semiconducting nature. The conductivity in the range of temperature (70−300 K) follows 3D VRH hopping mechanism. In kivelson model, the exponents are increased with increasing dopant concentration and was obeyed the power law. MR of the prepared DL−PLA/PANI composite films is strongly dependent on temperature, magnetic field, and concentration of HCl dopant. Negative MR is discussed in terms of a wave function−shrinkage effect on hopping conduction. In addition, we were discussed the response of carbon monoxide (CO) gas with polyaniline-based sensor materials.

Polyaniline based Composite for Gas Sensors

In this research work, we have demonstrated the synthesis, spectroscopic characteristics, thermal behaviour and DC conductivity of a few nanostructured composites, substituted conducting polymers (ICPs) and composites of ICPs. The physical properties of aforementioned composites are significantly changed by the doping with HCl, H2SO4, HNO3, H3PO4, or acrylic acid. The charge transport properties of these polymeric materials have been studied in detail because of their potential application in gas sensors. In the current work, varieties of conducting polymer based materials such as PANI-ES/Cloisite 20A nanostructured composite, acrylic acid (AA) doped PANI polymer, N-substituted conducting polyaniline polymer, DL−PLA/PANI-ES composites, poly methyl methacrylate (PMMA) based polyaniline composite, and inorganic acid doped polyaniline are sucessfuly synthesized using aniline/aniline hydrochloride as precursors in acidic medium. Particularly, AA based synthesised PANI polymer was found with higher solubility The spectroscopic, thermal stability, enthalpy of fusion, room temperature DC conductivity and temperature dependent DC conductivity measurements with and without magnetic was carried out with as-synthesized materials. The FTR/ATR−FTIR spectra indicated the presence of different functional groups in the as-prepared composite materials. The UV−Visible absorption spectroscopic analysis showed the presence of polaron band suggesting PANI-ES form. The Room temperature DC conductivity, temperature variation DC conductivity (in presence and absence of magnetic field), and magnetoresistance (MR) of as-prepared conducting polyaniline based were analysed. The highest room temperature DC conductivity value was obtained from H2SO4 doped based composite materials and all prepared conductive composites were followed ohms law. The low temperature DC conductivity was carried out in order to study the semiconducting nature of prepared materials. The Mott type VRH model was found to be well fitted the conductivity data and described the density of states at the Fermi level which is constant in this temperature range. From MR plots, a negative MR was observed, which described the quantum interference effect on hopping conduction. We discuss different gas analytes i.e., NO2, LPG, H2, NH3, CH4, and CO of conducting polymer based materials.