Dielectric behaviour and functionality of polymer matrix - ceramic BaTiO3 composites

Dielectric properties of polymer matrix - ceramic BaTiO3 composites were examined by means of Broadband Dielectric Spectroscopy (BDS) in the frequency range of 10(-1)-10(7) Hz and over the temperature range of 30-160 degrees C, varying the content of ferroelectric particles. Experimental results provide evidence that the recorded relaxation phenomena include contributions from both the polymeric matrix and the presence of the reinforcing phase. Obtained results are analysed via the electric modulus formalism. Polymer matrix exhibits two distinct relaxation processes attributed, with ascending relaxation rate, to glass/rubber transition, and local motions of polar side groups. Interfacial polarization or Maxwell-Wagner-Sillars process is present in the low frequency range and at high temperatures. Finally, in the vicinity of the characteristic Curie temperature (T-C) an abrupt variation of the real part of dielectric permittivity with temperature is recorded. This peak is probably related to the ferroelectric to paraelectric phase transition of the employed ceramic inclusions.