Dielectric relaxation and thermal studies on dispersed phase polymer nanocomposite films (original) (raw)
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The frequency dependent dielectric and conductivity behavior of a plasticized polymer nanocomposite electrolytes (PPNCEs) based on poly(ethylene oxide) + NaClO 4 with dodecyl amine modified montmorillonite (DMMT) as the filler and poly(ethylene glycol) as the plasticizer 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) and optical microscopy techniques. 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 electrolyte (PNCE) films. On addition of plasticizer, the peak shifts towards higher frequency side suggesting the speed up the relaxation time. 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 plasticizer concentration. Analysis of frequency dependence of dielectric and modulus formalism suggests that the ionic and polymer segmental motions are strongly coupled.
Physica B: Condensed Matter, 2015
The dielectric and conductivity response of polymer nanocomposite electrolytes (films of PMMA4LiClO4 dispersed with nano CeO2 powder) have been investigated. The dielectric behavior was analyzed via the dielectric permittivity (ε΄) and dissipation factor (tan δ) of the samples. The analysis has shown the presence of space charge polarization at lower frequencies. The real part of ac conductivity spectra of materials obeys the Jonscher power law. Parameters such as dc conductivity, hopping rate, activation energies and the concentration of charge carriers were determined from conductivity data using Almond West formalism. It is observed that the higher ionic conductivity at higher temperature is due to increased thermally-activated hopping rates accompanied by a significant increase in carrier concentration. The contribution of carrier concentration to the total conductivity is also confirmed from activation energy of migration conduction and from Summerfield scaling. The ac conductivity results are also well correlated with TEM results.
Dielectric and conductivity relaxations in PVAc based polymer electrolytes
Ionics, 2004
The polymer electrolytes composed of a blend of poly (vinyl acetate) (PVAc) and poly (methylmethacrylate) (PMMA) as a host polymer and LiClO4 as a salt are prepared by a solution casting technique. The formation of blend polymer- salt complex has been confirmed by FT-IR spectral studies. The conductivity- temperature plots are found to follow an Arrhenius nature. Arrhenius plot shows the decrease in activation energy with the increase in salt concentration. The dielectric behaviour of the sample is analysed using dielectric permittivity (ε′), dielectric loss (ε″) and electric modulus (M″) of the samples. The impedance cole- cole plot shows the high frequency semi- circle is due to the bulk effect of the material and the depression in the semicircle shows the non-Debye nature of the material. The bulk conductivity is found to vary between 2.5×10−5 Scm−1 to 1.7×10−3 Scm−1 with the increase of salt concentration of blend polymer samples. The migration energy derived from the dissipation factor is almost equal to the activation energy calculated from conductivity. The modulus spectrum of the samples shows the non-Debye behaviour of the polymer electrolyte films. The low frequency dispersion of the dielectric constant implies the space charge effects arising from the electrodes.
Studies of structural, thermal and electrical behavior of polymer nanocomposite electrolytes
Express Polymer Letters, 2008
Structural, thermal and electrical behavior of polymer-clay nanocomposite electrolytes consisting of polymer (polyethylene oxide (PEO)) and NaI as salt with different concentrations of organically modified Na + montmorillonite (DMMT) filler have been investigated. The formation of nanocomposites and changes in the structural properties of the materials were investigated by X-ray diffraction (XRD) analysis. Complex impedance analysis shows the existence of bulk and material-electrode interface properties of the composites. The relative dielectric constant (εr) decreases with increase in frequency in the low frequency region whereas frequency independent behavior is observed in the high frequency region. The electrical modulus representation shows a loss feature in the imaginary component. The relaxation associated with this feature shows a stretched exponential decay. Studies of frequency dependence of dielectric and modulus formalism suggest that the ionic and polymer segmental motion are strongly coupled manifeasting as peak in the modulus (M″) spectra with no corresponding feature in dielectric spectra. The frequency dependence of ac (alternating current) conductivity obeys Jonscher power law feature in the high frequency region, where as the low frequency dispersion indicating the presence of electrode polarization effect in the materials.
The Journal of Physical Chemistry C, 2019
The enhancement of conductivity of composite polymer as a dielectric material is an essential requirement for the electrostatic storage devices. We have modified the microstructure of the polymer matrix by introducing insulating nano filler SiO 2. The effect of such filler on the ionic conductivity of composite polymer electrolyte has been investigated using a variety of experimental techniques along with non-Debye type of relaxation functions. We have achieved optimum conductivity enhancement at a threshold filler concentration of 0.7 wt% in the blend polymer matrix composed of Poly (ethylene oxide) [PEO], Poly (vinilidene fluoride) [PVDF] (80:20) and salt NH 4 I (35 wt%). Such an enhancement of conductivity is a result of formation of highly conducting interphase region around the nano filler surface. The mobility of conducting species is found to increase enormously in the presence of filler. As a consequence, ionic conductivity of filler-induced blend polymer electrolyte increases three times of its magnitude (3.02 × 10-3 S/cm) compared to that without filler. The occurrence of two different activation energies which decrease with increasing filler concentration, as determined from temperature dependent conductivity, has been well explained from dynamics of free and contact ions. A non Debye behaviour of relaxation properties has been analysed using a newly approached one parameter Mittag-Lefler function. The experimental decay
Conductivity and thermal studies of blend polymer electrolytes based on PVAc–PMMA
Solid State Ionics, 2006
The polymer electrolytes comprising blend of poly(vinyl acetate) (PVAc) and poly(methylmethacrylate) (PMMA) as a host polymer and LiClO4 as a dopant are prepared by solution casting technique. The amorphous nature of the polymer–salt complex has been confirmed by XRD analysis. The DSC thermograms show two Tg's for PVAc–PMMA blend. A decrease in Tg with the LiClO4 content reveals the increase of segmental motion. Conductance spectra results are found to obey the Jonscher's power law and the maximum dc conductivity value is found to be 1.76 × 10− 3 S cm− 1 at 303 K for the blend polymer complex with 20 wt.% LiClO4, which is suitable for the Li rechargeable batteries. The conductivity–temperature plots are found to follow an Arrhenius nature. The dc conductivity is found to increase with increase of salt concentration in the blend polymer complexes.
DC-Ionic Conductivity and Dielectric Studies of PVP-CH 3 COOK Based Solid Polymer Electrolyte Films
Solid polymer electrolyte films were prepared with different wt% compositions of PVP-CH3COOK by solution cast technique. DC ionic conductivity measurements for the prepared nanocomposite films were performed by lab made conductivity four probe method. From the measurements the higher ionic conductivity was found to be 2.31x10-5 S/cm at 373 K for the composition 80PVP:20CH3COOK. Dielectric studies were performed on the prepared polymer films at room temperature in the frequency ranging between 5000 Hz and 50000 KHz to find the best optimum conductivity and electric relaxation process of the samples.
Open Journal of Organic Polymer …, 2012
Polymer blend electrolytes, where PEO-PMMA polymer blend is used as polymer host matrix, doped with AgNO 3 and plasticized with ethylene carbonate (EC) and Al 2 O 3 as nano-filler were synthesized using the solution cast techniques. The polymer films were characterized by impedance spectroscopy, XRD, DSC, SEM, FT-IR and ionic transport measurements. The results indicate an enhancement in conductivity of PEO-PMMA-AgNO 3-EC polymer electrolytes. The ionic conductivity of the polymer films is also found to increase with temperature. Electrical properties of polymer films in the framework of dielectric and modulus formalism are studied and discussed.
Ionics, 2017
In the present work, the effect of different nanofiller (BaTiO3, CeO2, Er2O3 or TiO2) on blend solid polymer electrolyte comprising of PEO and PVC complexed with bulky LiPF6 have been explored. The XRD analysis confirms the polymer nanocomposite formation. FTIR provides evidence of interaction among the functional groups of the polymer with the ions and the nanofiller in terms of shifting and changing peak profile. The highest ionic conductivity is ~2.3×10-5 S cm-1 with a wide electrochemical stability window of ~3.5 V for 10 wt. % Er2O3. The real and imaginary part of dielectric permittivity follows the identical trend of the decreasing value with increase in the frequency. The particle size and the dielectric constant shows an abnormal trend with different nanofiller. The ac conductivity follows the universal power law. An effective mechanism has been proposed to understand the nanofiller interaction with cation coordinated polymer in the investigated system. storage/conversion devices must have (a) high ionic conductivity; (b) electrochemical stability window (>4 V); (c) low melting point; (d) high boiling point; (e) high chemical stability; (f) nontoxicity; (g) low cost and good compatibility with electrodes. Solid polymer electrolyte (SPEs) plays a dual role as an electrolyte as well as a separator which keeps both electrodes separate and avoids the user from using a spacer as in liquid electrolyte system. The first report on ionic conduction was given by P. V. Wright [5] and Fenton et al [6] in 1973 and it was concluded that polymer host dissolved with an alkali metal salt results in an ionic conductive system. The first application of novel polymer electrolyte in batteries was announced by Armand and his co-workers in 1978 [7]. Most devices are based on liquid/gel polymer electrolytes due to their high ionic conductivity (10-3-10-2 Scm-1) and compatible with
Journal of Non-Crystalline Solids, 2011
A novel combination of dispersed phase polymer nanocomposite electrolyte (PNCE) series based on an amorphous polymer host (PMMA) 4-LiClO 4 complex dispersed with nanocrystalline CeO 2 is reported. XRD analysis has confirmed the dispersed phase nanocomposite formation. Effect of nano CeO 2 dispersion on ion-ion and ion-polymer interactions has been analyzed. A drastic enhancement in electrical conductivity, by 2 orders of magnitude at 30°C and 5 orders of magnitude at 100°C, has occurred on nano CeO 2 dispersion when compared with room temperature conductivity of undispersed PS film. An excellent correlation between variation of d.c. conductivity and free mobile charge carriers has been observed. An ion conduction model is proposed. Strength of the model lies in the experimental evidences from FTIR, conductivity and TEM analyses. Thermal analysis indicates a strong dependence of thermodynamical parameters, e.g., glass transition temperature (T g), crystalline melting temperature (T m), enthalpy etc. on filler addition. Substantial improvement in voltage stability (~4.4 V), thermal stability and ion transport properties has been noticed on nano CeO 2 dispersion.