Improving dielectric properties, electrical conductivity, and thermal properties of biodegradable polymer composites prepared with lanthanum

The precipitation method was adapted to synthesize the poly(epsilon-caprolactone-copolymer- ethylene oxide) (epsilon-CL-co-EO) composite with the salt of lanthanum (La), a rare earth element. This salt was incorporated into the polymer of different weight percentages to study how it affects the thermal and dielectric properties of the polymer. The resulting products were characterized by Fourier Transform Infrared Spectroscopy, X-ray diffractometry (XRD), Scanning electron microscopy (SEM) and thermogravimetric analysis. XRD and SEM data show that the polymer mixes homogeneously with the metal salt. Thermal degradation data show that the thermal stability of composites synthesized with La is lower than that of pure polymer. The dielectric properties and A.C conductivity measurements of the composites were investigated by using impedance analyzer in the frequency range (100 Hz to 20 kHz) at room temperature. The electrical property results of (epsilon-CL-co-EO)/La composites displayed that dielectric constant (epsilon), dielectric loss (epsilon"), tan delta (tan delta) and A.C electrical conductivity (sigma(ac)) increase with increasing La content. The largest conductivity of (epsilon-CL-co-EO)/La composite filled with 20 wt% La was 8.80 x 10(-8) S/cm, which was 162% times pure (epsilon-CL-co-EO). In addition, impedance (IZI) of composites was evaluated from the dielectric data. This procedure is eco-friendly and easy to handle, which provides a promising route to polymer composites in the application of the conductivity field.