Enhanced dielectric and electrical properties of three-component PMMA–NaNbO3–starch percolative composite films

Three-component PMMA–NaNbO₃–starch percolative composites with starch and sodium niobate (NaNbO₃; NN) particles embedded into poly(methylmethacrylate) (PMMA) matrix were prepared using solution casting technique. The structure, dielectric and electrical properties of the three-component PMMA–NN–starch composites containing starch in (PMMA + NaNbO₃) matrix as function of frequency and the different weight percentages of starch were employed. The experimental results showed that the three-component PMMA–NN–starch composite has a superior dielectric constant (≈395) and suppressed dielectric loss (< 0.6) at 100 Hz. Moreover, the improvement of electrical properties of the composites may be attributed to the synergistic effect of the NN ceramics and conductive starch particles within the polymer matrix. The homogeneous dispersion gives an insulating layer between neighboring conductive starch particles in the PMMA matrix, which not only prevent the direct contact of starch but also provides with better homogeneity of the starch particles in the composite system. Furthermore, the percolation theory is utilized to elucidate the dielectric and electrical performance of the composite. These three-component PMMA–NN–starch composite exhibited an insulator–conductor transition with 7 wt% of starch contents at percolation threshold. This work might be a new approach to produce excellent composite films with enhanced dielectric and electrical properties for high performance energy storage applications.