Dielectric spectroscopy during extrusion processing of polymer nanocomposites: a high throughput processing/characterization method to measure layered silicate content and exfoliation

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].…”

Humidity Dependence of Proton Conductivity in DNA Film Studied by NMR and AC Conductivity

“…It is noted that of 10 -3~1 0 -4 sec is observed in the dielectric relaxation seen in the binding molecule such as ethylene-co-vinyl acetate and polyamide and so on. 15) Moreover, water molecules with long relaxation times are found mainly around the DNA phosphate group. Considering these results, in region II, the water bridges around phosphate group such as the PO 4 -water bridge increase and connect, and therefore increases by increasing humidity.…”