T. Sheela

Ionic conductivity and dielectric studies of LiClO4 doped poly(vinylalcohol)(PVA)/chitosan(CS) composites

This paper focuses on the dielectric constant (e′), dielectric loss factor (e″) and frequency dependent conductivity (σac) properties of newly prepared poly(vinylalcohol) (PVA) chitosan (CS) composite films incorporated with different concentrations of LiClO4. The composite films were prepared using solution casting technique. The complexation between salt and polymer host is confirmed by FT Raman and UV-Vis studies. The sample containing 20 wt.% LiClO4 exhibits a highest ionic conductivity of 3 × 10-6 S/cm at room temperature. The dielectric properties of the composites follow non-Debye behavior.

Thermal, mechanical and dielectric properties of poly(vinyl alcohol)/graphene oxide composites

In this work the composite films of poly(vinyl alcohol) (PVA) doped with functionalized Graphene Oxide (GO) were prepared by solution casting method. The films were characterized using FT-IR, DSC, XRD, mechanical properties and dielectric studies at room temperature. FTIR spectra shows the formation of hydrogen bonds between hydroxyl groups of PVA and the hydroxy groups of GO. The DSC thermograms shows the addition of GO to PVA greatly improves the thermal stability of the composites. XRD patterns shows that the GO exfoliated and uniformly dispersed in PVA matrix. Mechanical properties are significantly improved in PVA/GO composites. The tensile strength increased from 8.2 to 13.7 MPa and the Young’s modulus increased from 7.5 to 24.8 MPa for 5 wt% GO doped sample. Dielectric spectroscopy showed a highest dielectric constant for the 5 wt% GO doped PVA films. This work provides a potential design strategy on PVA/GO composite, which would lead to higher-performance, flexible dielectric materials, high charg...

Influence of transport parameters on conductivity of lithium perchlorate-doped poly(vinyl alcohol)/chitosan composites

This article focuses on the calculation of transport parameters (number density of ions and time travel of ions between sites, mobility, diffusion coefficient, and number of transitions per unit time) of the lithium perchlorate (LiClO4)-doped poly(vinyl alcohol)/chitosan (PVA/CS) composites using Rice and Roth model. The thermal study reveals a decrease in glass transition temperature for LiClO4-doped PVA/CS composites. The highest ionic conductivity of 3 × 10−6 S cm−1 at room temperature is observed for the 20 wt% LiClO4-containing composite. The temperature-dependent conductivity follows Arrhenius relation and lowest activation energy of 0.153 eV is observed for highest conducting sample. The mechanical properties such as Young’s modulus, stiffness, and tensile strength decreases and its percentage elongation at break increases with increase in LiClO4-doping level in PVA/CS polymer matrix. The scanning electron microscopic images exhibit smooth and homogeneous surface of PVA/CS composite.

Photochromic and microstructural properties of methyl orange doped poly(vinyl alcohol)

The effect of Methyl Orange (MO) dye on microstructural, optical and fluorescence properties of the polymer Poly(vinyl alcohol) (PVA) is studied. The FTIR study shows the appearance of new peaks indicates the interaction of MO with PVA. The UV-Vis study shows three absorption regions with the first two shows red shift and the third one shows blue shift and hence correspondingly three optical energy band gaps. In fluorescence study, it is observed that the intensity increases with increasing wavelength. These results are understood by invoking the hydrogen bonding and hydrophobic interaction between PVA and MO, forms the charge transfer complex (CTC).

Effect of Al2O3 on dielectric behavior of LiClO4/PVA polymer electrolytes

The dielectric properties of lithium per chlorate (LiClO4)/polyvinylalcohol (PVA) solid polymer electrolyte dispersed with alumina (Al2O3) nanoparticles have been investigated in this work. Free standing films of Al2O3/LiClO4/PVA were prepared using solution casting method. FTIR results confirm the successful dispersion of Al2O3 in LiClO4/PVA polymer matrix. The variation in dielectric constant follows Non-Debye type behavior. The interfacial polarization phenomenon is the main reason for lower frequency regime variation in dielectric properties. The inertial properties of the dipoles play vital role in higher frequency regime. The composites with 5wt% Al2O3doped LiClO4/PVA show highest conductivity, can be used as an electrolyte with certain attainable modifications.

Synthesis and characterization of multifunctional ZnBr2/PVA polymer dielectrics

Different weight percentage of ZnBr2 doped poly(vinyl alcohol) (PVA) free standing composite films were prepared using solution casting method. These films were characterized for analyzing structural, dielectric, electrochemical properties. This paper mainly focused to understand the contribution of physical phenomenon on conductivity in terms of dielectric parameters. FTIR spectrum confirms the interaction between ZnBr2 and PVA. Pseudo-capacitive behavior observed from cyclic voltammograms. Dielectric properties of the composites follow non-Debye type behavior. The conducting phenomenon occurs due to hopping of ions between coordination sites present in the composite and the segmental relaxation of polymer chain.

Dielectric, thermal and mechanical properties of ADP doped PVA composites

Polymer composites of poly(vinyl alcohol) (PVA), doped with different concentrations of ammonium dihydrogen phosphate (ADP) has been prepared by solution casting. The formation of complexation between ADP and PVA was confirmed with the help of Fourier transforms infrared (FTIR) spectroscopy. Thermogravimetric analysis (TGA) shows thermal stability of the prepared composites. Impedance analyzer study revealed the increase in dielectric constant and loss with increase the ADP concentration and the strain rate of the prepared composites decreases with ADP concentration.

Ionic conductivity studies in crystalline PVA/NaAlg polymer blend electrolyte doped with alkali salt KCl

Potassium Chloride (KCl) doped poly(vinyl alcohol) (PVA)/sodium alginate (NaAlg) in 60:40 wt% polymer blend electrolytes were prepared by solution casting method. The complexation of KCl with host PVA/NaAlg blend is confirmed by FTIR and UV-Vis spectra. The XRD studies show that the crystallinity of the prepared blends increases with increase in doping. The dc conductivity increases with increase in dopant concentration. Temperature dependent dc conductivity shows an Arrhenius behavior. The dielectric properties show that both the dielectric constant and dielectric loss increases with increase in KCl doping concentration and decreases with frequency. The cole-cole plots show a decrease in bulk resistance, indicates the increase in ac conductivity, due to increase in charge carrier mobility. The doping of KCl enhances the mechanical properties of PVA/NaAlg, such as Youngs modulus, tensile strength, stiffness.

Preparation and characterization of NaClO4 doped poly(vinyl alcohol)/sodium alginate composite electrolyte

The 60:40 wt% poly(vinyl alcohol) (PVA)/sodium alginate blend doped with different concentrations of NaClO4 composite films were prepared by solution casting method. The prepared samples were characterized by FTIR, UV-Vis, DC and AC conductivity. The FTIR spectra confirms the complexation of NaClO4 with host polymer blend. From the UV-Vis spectra, the calculated optical band gap decreases from 5.2eV to 4.6eV. The frequency dependent dielectric constant decreases, and hence the dielectric loss and ac conductivity increases with doping level. The mechanical study shows the Young’s modulus, tensile strength, stiffness were increases with the NaClO4 concentrations.

Optical and dielectric properties of TiO2doped PVA-CN/LiClO4composite electrolyte

Solid polymer electrolyte (SPE) composite films of PVA-CN-HOBt-LiClO4 doped with TiO2 were prepared by solution casting method. The films were characterized using FT-IR, UV-Vis, DSC and Dielectric studies at room temperature. The FTIR results show the interaction of TiO2 nanoparticles with PVA-CN-HOBt-LiClO4 composite. The optical absorbance of the composite films increases from 250nm to 400nm with increase in doping and optical band gap (Eg) decreases from 3.2eV to 3.1eV. The glass transition temperature increases with increase in doping level. The dielectric properties of the composites show that these composite films can be used for SPE nanocomposites.