Analysis of the dielectric relaxation in reduced graphene oxide/epoxy composites materials using the modulus formalism.

This work reports an analysis of the dielectric properties of reduced graphene oxide mixed into epoxy resin, diglycidyl ether of bisphenol A, in the frequency range 10[Formula: see text]-10[Formula: see text] Hz and over the temperature range of 300-400 K, using impedance spectroscopy. For this study, a series of samples were prepared with various filler contents. Using the electric modulus formalism, it has been found that these composites exhibit below and above the percolation threshold [Formula: see text] a critical behavior of the dielectric relaxation phenomenon due to the single [Formula: see text]-relaxation, which is associated with the glass-rubbery transition of the epoxy matrix above the glass transition temperature.

Dielectric spectroscopy of melt-extruded polypropylene and as-grown carbon nanofiber composites.

In this work, different weight contents of as-grown carbon nanofibers (CNFs), produced by chemical vapor deposition, were melt-extruded with polypropylene (PP) and their morphologic, structure and dielectric properties examined. The morphologic analysis reveals that the CNFs are randomly distributed in the form of agglomerates within the PP matrix, whereas the structural results depicted by Raman analysis suggest that the degree of disorder of the as-received CNFs was not affected in the PP/CNF composites. The AC conductivity of PP/CNF composites at room temperature evidenced an insulator-conductor transition in the vicinity of 2 wt.