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Abstract
Polymer composites and nanocomposites are relatively new class
of advanced materials that are helping to meet the demand of new
technology. Because of their unique behavior, these materials are suitable
for a wide range of applications.
This work aims to study the dielectric properties in relation to
structural composition of Nylon 6/CaCO3 composites. In order to achieve
this goal, three composite groups of different sizes, namely, 4 μm, 2 μm
and 70 nm, of the CaCO3 were prepared and characterized. Each of the
three groups contains four loadings 2, 4, 6 and 10 wt% of the CaCO3
subdivided into surface modified CaCO3 with oleic acid and unmodified
one. Surface modification was investigated using sedimentation
experiments and Transmission Electron Microscope (TEM). Thermal
Gravimetric Analysis (TGA), and Differential Scanning Calorimetry
(DSC), were used to study thermal stability and glass transition
temperature of the samples under investigation. The molecular
relaxations processes and charge transport are investigated in a wide
frequency and temperature ranges by mean of Broadband Dielectric
Spectroscopy (BDS), Thermal Stimulated Depolarization Current
(TSDC) and LCR-Bridge. The obtained results were discussed and
interpreted in the scope of the updated theories. The dielectric relaxation
spectra were fitted with Havriliak-Negami equation and the mean
relaxation rates and the dielectric relaxation strengths were observed. The
temperature dependence of the mean relaxation rates, , was
described using either the Vogel-Fulcher-Tammann, VFT, for the MWS
and -relaxations, or an Arrhenius type relation for , and - relaxations. The results show the unplasticizing effects as well as
resistivity increase in the direction of decreasing the filler size even at the
nano size without any surprising trend.