Calorimetric and dielectric study of a blend containing a conductive polymer: poly(3-octylthiophene) plus poly(ethylene-co-vinylacetate)

The phase diagram of the binary system poly(3-octylthiophene) + poly(ethyle ne-co-vinylacetate), P3OT + EVA was studied by Differential Scanning Calori metry (DSC). The blends of low and high content of P3OT were found to be ho mogeneous. The system was also studied by a dielectric relaxation technique in the frequency range 20 Hz-100 kHz. The complex electric modulus M* is d iscussed in terms of the well-known Havriliak-Negami function. We also obta ined the spectrum of relaxation times using a regularization technique. The spectra allowed us to calculate the d.c. conductivity. A low frequency con tribution to the dielectric loss found in two-phase samples was attributed to interface polarisation effects. (C) 1999 Elsevier Science Ltd. All right s reserved.