Nylon 6/ clay nanocomposites were studied by dielectric relaxation spectroscopy (DRS) to correlate morphology and microstructure with relaxation behavior of the polymer matrix at the molecular level. Two types of microstructure, agglomerated and exfoliated, were prepared by extruding nylon 6 with surfactant-treated montmorillonite clays. A new on-line dielectric slit die sensor was used to examine the melt state properties during extrusion compounding. Solid state properties were probed by off-line DRS over a temperature range from -50 C to 180 C in a frequency range from 10-3 Hz to 106 Hz. Using non-linear regression methods, the experimental data were fit with the Cole-Cole dielectric dispersion function corrected for electrode polarization and DC conductivity. Characteristic frequency, relaxation strength, and, DC conductivities were extracted from curves with overlapping relaxation modes. Two dielectric dispersions were observed in the composite melt: the α relaxation associated with molecular segmental motion, and a Maxwell-Wagner interfacial polarization attributed to the resin/clay interface. Analysis of the solid state data yielded a comprehensive master plot of dielectric dispersions that include the standard α, Beta, and Gamma dispersions and other dispersions associated with water, the crystal/amorphous interface, and Maxwell-Wagner interfacial polarization attributed to the resin/clay interface. Analysis of the solid state data yielded a comprehensive master plot of dielectric dispersions that include the standard α, Β, and γ dispersions and other dispersions associated with water, the crystal/amorphous interface, and Maxwell-Wagner processes. For example, we found that localized α relaxation deviates more from the main α relaxation upon the addition of fillers as the heterogeneity of the system yields a broader range of dynamics. Crystallization of nylon 6, filler/matrix interaction and plasticization due to trapped moisture are altered in the presence of microstructures associated with different clays.
Citation: Journal of Polymer Science Part B-Polymer Physics
Pub Type: Journals
clay nanocomposites, DC conductivity, dielectric properties, dielectric relaxation, dielectric spectroscopy, electrode polarization, exfoliated, nylon 6