Investigation of Dielectric Relaxation in Biodegradable Polymer Blends for Capacitor Applications

Biodegradable polymer-based dielectrics offer environmentally sustainable alternatives to conventional petroleum-derived capacitor films, with potential for manufacture from Nigerian agricultural-derived biopolymers including starch, cellulose, and polylactic acid. Understanding dielectric relaxation dynamics in these materials is essential for evaluating their suitability for capacitor applications across the relevant frequency range. This study investigates dielectric relaxation in binary blends of cassava starch and polylactic acid prepared by solution casting at blend ratios of 100:0, 75:25, 50:50, 25:75, and 0:100. Dielectric permittivity and loss tangent are measured over the frequency range of 100 Hz to 10 MHz and the temperature range of 25 to 100 degrees Celsius using an LCR bridge with a parallel plate capacitor cell. Dielectric relaxation parameters including relaxation time, distribution parameter, and activation energy are extracted by fitting Cole-Cole and Havriliak-Negami functions to the measured dielectric spectra. Results indicate that the 50:50 blend achieves the most favourable combination of high permittivity (3.8 at 1 kHz) and low loss tangent (0.028) at ambient temperature. The study contributes to materials development for eco-friendly capacitors using Nigerian biopolymers. Keywords: dielectric relaxation, biopolymer, starch, polylactic acid, capacitor