Microstructural evolution of electrically activated polypropylene/layered silicate nanocomposites investigated by in situ synchrotron wide-angle X-ray scattering and dielectric relaxation analysis

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

“…Wang et al [20] also concluded that a large amount of exfoliated MMT clay structures in PCNs enhances the T g value and simultaneously reduces the ε s value. The increase in τ value is also related to the increased amount of layered silicate surface area as a result of the increased degree of exfoliation [24,28]. Above 1 wt% MMT clay loading both the interfacial area and intercalation are enhanced and more PVA chains are confined between the MMT clay sheets.…”

“…The decrease in polymer chain segmental mobility relaxation time in nanocomposite provides an explanation for the increased thermal and mechanical stability in the PCNs. Davis et al [24], Kim et al [28], and Sengwa et al [34] also concluded that the increase of τ value represents an increase in clay exfoliation in the PCNs. At varying MMT clay concentrations, good resemblance is observed between the change in the ε s and τ values (Figure 3).…”

“…Further, the formation of the hydrogen bonds between the PVA vinyl alcohol group and silicate oxygen force the PVA chains to create long adsorbed trains due to the atomically smooth dispersed MMT surfaces. The large reduction in ε′ value at 1 wt% MMT clay concentration in PVA-MMT clay nanocomposites also suggests that the amount of exfoliated structures is very high as compared to that of the PVA intercalated clay structures [14,15], which is the common characteristics of solution grown PCNs at very low clay concentration [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34]. The loss part ε″ spectra of complex dielectric function ( Figure 1b) reflects the presence of two relaxation processes in the PVA-MMT clay nanocomposite films over the frequency range 20 Hz-1 MHz, which can be seen in their complex plane plots (ε″ vs. ε′) (Figure 2).…”

“…The complex dielectric function, alternating current (ac) electrical conductivity, impedance properties and electric modulus spectra of the PVA-MMT clay nanocomposite films were investigated over the frequency range 20 Hz to 1 MHz. An attempt is made to correlate the values of various dielectric parameters with structural behaviour of these nanocomposites materials to establish the use of dielectric relaxation spectroscopy as diagnostic tool for the development of on-line testing and monitoring of the nanocomposite formation in PCNs materials [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33].…”

Interfacial effects on the dynamics of ethylene–propylene copolymer nanocomposite with inorganic clays

“…One key factor in the fabrication of good polymer-clay nanocomposites is the capability of obtaining good dispersion of the individual silicate platelets in the matrix and a good adhesion between polymer molecules and the platelets. Several approach has been proposed to this scope such as the organo-modification of the silicate [13], the compatibilization of the polymer chain toward the inorganic component [14,15], the application of ac electric field [16], the development of the polymerization reaction in presence of the silicate [7,17]. Even though macroscopic characterizations of the materials obtained by the above procedures are reported, a true understanding of their effects on the properties of the polymer-MMT interfaces is still lacking.…”