Electrical relaxation dynamics in TiO2 – polymer matrix composites

• DOI: 10.3144/expresspolymlett.2007.108
• Publication Date: 2007-12-10T14:25:18Z
• Authors: G. A. Kontos; A. L. Soulintzis; P. K. Karahaliou; G. C. Psarras; S. N. Georga; C. A. Krontiras; M. N. Pisanias
• Keywords: Polymer composites; 3CHEU; polar oxide; Chemical technology; TA401-492; TP1-1185; 02 engineering and technology; particulate filler; 0210 nano-technology; dielectric spectroscopy; Materials of engineering and construction. Mechanics of materials

Polymer matrix-TiO2 composites were prepared in three different filler concentrations. The electrical relaxation dynamics as well as the electrical conductivity of all samples were examined by means of Broadband Dielectric Spectroscopy (BDS) over a wide frequency and temperature range. The recorded relaxation response includes contributions from both the polymer matrix and the reinforcing phase. Two relaxation modes (β and γ) are observed in the low temperature region, which are attributed to the re-orientation of polar side groups of the matrix and rearrangement of small parts of the polymeric chain respectively. The α-relaxation and the Maxwell-Wagner-Sillars effect (MWS), attributed to the glassrubber transition of the polymeric matrix and to interfacial polarization phenomena respectively, are observed in the high temperature region. These two mechanisms are superimposed, thus a computer simulation procedure was followed in order to distinguish them. MWS effect becomes more pronounced with increasing concentration of the filler following an Arrhenius behaviour. The relaxation frequencies corresponding to α-mode follow the Vogel-Tamann-Fulcher (VTF) equation. An additional relaxation mode is recorded at relatively high temperatures and high frequencies. Its occurrence and dynamics are related to the presence and the concentration of the filler. Finally, the Direct Current (DC) conductivity follows the VTF equation.