Investigations on dielectric properties of PVDF/PMMA blends

Poly(vinylidene fluoride) (PVDF)/poly(methyl methacrylate) (PMMA) blend films of thickness 100 mm were prepared by solution casting technique with compositions of PVDF/PMMA blends as 0:100, 10:90, 30:70, 50:50. The structural characterization of these blend films was done from the data obtained by XRD and FTIR techniques. The dielectric behaviour of these blends is expressed in the variation of electric parameters viz. complex dielectric function ε, electrical conductivity σac and electric modulus M in the frequency range 1 KHz–1 MHz at ambient temperature, obtained using Wanyne Kerr 6500B impedance analyzer. The structural characterization techniques revealed α and β phases of PVDF to coexist in these blends. The β-phase aligns the dipoles parallel rendering an augmentation in polarization mechanism of the material. The structural and electrical studies reveal that β-phase gets increased with PVDF concentration till the concentration does not exceed 30 wt% in these blends. Thereafter α phase becomes equally significant. The effect of this is observed clearly in the variation trends of the dielectric constant, dielectric loss and electric conductivity of the samples. The electric modulus studies exhibit the modulus relaxation peaks which are relatively sharper than those of the tanδ spectra. The peak modulus shifts towards higher frequency side on increase of PVDF content which infers that there is a reduction in the polymer–polymer interaction strength facilitating the cooperative chain segmental dynamics in the blend films.