MICROWAVE TRANSMISSION, REFLECTION AND DIELECTRIC-PROPERTIES OF CONDUCTING AND SEMICONDUCTING POLYPYRROLE FILMS AND POWDERS

Microwave transmission, reflection and some dielectric properties Of the conducting polymer, polypyrrole, are presented. Methods are discussed for determining microwave transmission and reflection of electrochemically synthesized and doped polypyrrole films with conductivities ranging from 0.1-5000 S m-1. Polypyrrole films were placed between waveguides and irradiated with microwaves centred at frequencies 2.45 and 1 0 G Hz with 0.1 G Hz span. The results indicate that the conductivity of doped polypyrrole films has a significant effect on both transmission and reflection. Microwave opacity of polypyrrole varied with the synthesis conditions of the polymer. Samples with low conductivity exhibited high transmission whereas low transmission readings were observed with highly conducting films. Dielectric properties are also presented for frequencies from 100 to 10(6) Hz in a temperature range of 90-280 K and at microwave frequencies of 2.45 and 10 GHz. These measurements indicate that the real and imaginary parts of the dielectric constant increase in magnitude with increasing doping level.