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Broadband dielectric spectroscopy (10 À1 to 10 6 Hz) in combination with TSDC were employed to study the relaxations and the conductivity phenomena in polyamide 6/CaCO 3 composites loaded with different contents and particle sizes of treated and untreated CaCO 3 . In addition to the primary a-relaxation associated with the glass transition, significant interfacial relaxation and ionic conduction processes have been revealed. The temperature dependence of the relaxation rates of a-relaxation and Maxwell-Wagner-Sillerprocess as well as that of the hopping rate of the conduction mechanism were found to follow the Vogel-Fulcher-Tammann-model. This may support the idea that the three mechanisms are not completely independent. The modification of the filler does not add any effect on the resistivity values.

Several polymer composites formed from nylon 6/CaCO 3 with different ratios and particle sizes were prepared using modified and unmodified CaCO 3 as inorganic filler. The modification of CaCO 3 surfaces was carried out by adsorption of oleic acid from toluene. TGA and DSC measurements show that the glass transition temperatures reduced by the presence of inorganic filler, whereas the melting temperature did not influenced. In all prepared polymer composites, the presence of filler accelerates the degradation process of the polymer. Dielectric properties of the investigated samples were studied in the frequency range from 45 Hz to 1 MHz and at temperatures ranging between 50 and 200• C. The presence of CaCO 3 led to a remarkable decrease in the conductivity of nylon 6.

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