POLYANILINE CELLULOSE-ACETATE BLENDS - TR ANSPORT-PROPERTIES

Several series of conducting blends based on polyaniline in a cellulos e acetate matrix have been studied regarding their transport propertie s. The de conductivity exhibits a percolative behavior with a remarkab ly low conduction threshold, lower than 1% wt. polyaniline. As a funct ion of temperature, the conductivity follows the typical law for hoppi ng : In(sigma)proportional to -(T-o/T)(gamma) with 0.5 less than or eq ual to gamma less than or equal to 1, depending on the concentration. Magnetoresistance is found to be positive, roughly identical for each serie, and proportionnal to (B/T)(2). ac conductivity measurements yie ld a dispersive behavior:sigma(omega) proportional to (omega/omega(o)) (u) for omega>>omega(o) with u approximate to 0.7 and omega(o) proport ional to sigma(omega=O) whatever the temperature, which is characteris tic for ac transport in disordered media. Finally, ESR linewidth shows a maximum as a function of temperature, that can be attributed to the microscopic metallic nature of charge tranport.