Studies of dielectric relaxation and a.c. conductivity in cellulose acetate hydrogen phthalate–poly(methyl methacrylate) blends

Dielectric constant, dielectric loss and a.c. conductivity of polyblends of cellulose acetate hydrogen phthalate(CAP) and poly(methyl methacrylate) (PMMA) of different compositions have been measured in the temperature range 300–430 K and in the frequency range 50–100 kHz. Variations in dielectric constant with temperature of the blends exhibit unique behavior, different from the component polymers. In the blends, the dielectric loss as a function of temperature displays a single peak corresponding to the glass transition temperature (Tg), in the region between the Tg values of the pure polymers. The Tg values observed agree well with those values obtained from DSC. Dielectric studies show that CAP forms miscible blends with PMMA. AC conductivity values are calculated from dielectric data and the conduction mechanism is discussed.