Investigation of correlation between dielectric parameters and nanostructures in aqueous solution grown poly(vinyl alcohol)-montmorillonite clay nanocomposites by dielectric relaxation spectroscopy

Abstract

Abstract. Poly(vinyl alcohol) (PVA)-montmorillonite (MMT) clay nanocomposite films up to 10 wt% clay concentration were synthesized by aqueous solution grown technique. The relative complex dielectric function, alternating current electrical conductivity, electric modulus and impedance properties of these organic-inorganic nanocomposites were investigated in the frequency range from 20 Hz to 1 MHz at ambient temperature. The PVA-MMT clay nanocomposite films show a large decrease in the real part and loss of relative dielectric function at 1 wt% MMT clay loading compared to pure PVA film and anomalous behaviour is observed with further increase of clay concentration in PVA matrix. Two dielectric relaxation processes were observed in these nanocomposites; a high frequency relaxation associated with PVA segmental motion and a low frequency relaxation resulting from PVA/dispersed MMT clay interfacial polarization (Maxwell-Wagner relaxation). Dielectric relaxation times corresponding to these processes were determined by fitting dc conductivity corrected complex dielectric function data to the Havriliak-Negami expression. A correlation between change in dielectric relaxation strength, relaxation time and hindrance to the PVA-chain dynamics with the degree of exfoliated structures of dispersed nanoscale MMT clay filler in the PVA matrix were explored. Results confirm the application of dielectric relaxation spectroscopy as a potential tool in the confirmation of nanocomposite formation and their structure characterization.

Dielectric spectroscopy and confirmation of ion conduction mechanism in direct melt compounded hot-press polymer nanocomposite electrolytes

“…In the PEO matrix, MMT nanoplatelets form the hybrid structures (intercalated and exfoliated) due to their hydrophilic behaviour. The predominance of intercalated or exfoliated structures of MMT, respectively, governs the increase or decrease of ε′ values, as compared to that of the pristine polymer matrix [22,[25][26][27][28][29]. The inset of Fig.…”

“…Dielectric studies of the polymer clay nanocomposite establish the fact that the comparative changes in ε′ values with the MMT concentration in the polymer matrix possess strong correlation with the intercalated/exfoliated MMT structures [17][18][19][20][21][22][25][26][27][28][29]. In the PEO matrix, MMT nanoplatelets form the hybrid structures (intercalated and exfoliated) due to their hydrophilic behaviour.…”

Dielectric dispersion and relaxation studies of melt compounded poly(ethylene oxide)/silicon dioxide nanocomposites

“…values have anomalous decrease with the increase of SiO 2 concentration in the nanocomposites. The values of various relaxation times are found in the order s e [ s tan d [ s M for these nanocomposite films, which is a common characteristic of several polymeric dielectric materials[23][24][25][26]. Further, the relaxation time values of the nanocomposites are found significantly low as compared to that of the pure PEO film.From Fig.…”

“…The modulus spectra are commonly studied for the solid dielectrics because they are free from contribution of electrode polarization effect and also independent of the electrode material, electrode/dielectric contact and the adsorbed impurities in the dielectric sample [23][24][25][26]. Figure 5 shows the spectra of real part M 0 and loss M 00 of the electric modulus of PEO-x wt% SiO 2 nanocomposites.…”

“…Our survey of literature revealed that, so far the PEO and SiO 2 interactions and their effect on the polymer physico-chemical properties are characterized by rheological, differential scanning calorimetry (DSC), thermo gravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), dynamical mechanical analysis (DMA), X-ray diffraction (XRD) scanning electron microscopy (SEM) and transmission electron microscopy (TEM) measurements [1,[3][4][5][6][7]19]. Besides these experiments, the dielectric relaxation spectroscopy (DRS) is also a powerful tool for the study of polymer and nanofiller interactions and their effect on polymer dynamics in the PNC materials [20][21][22][23][24][25][26][27][28][29][30][31]. Further, the investigation on dielectric properties of such PNCs can provide the in-depth discussion of nanodielectrics, which is an emerging and fast-moving topic in electrical insulation for microelectronic devices.…”