Enhancing Dielectric Properties, Thermal Conductivity, and Mechanical Properties of Poly(lactic acid)-Thermoplastic Polyurethane Blend Composites by Using a SiC-BaTiO Hybrid Filler.

A composite of polymer blends-thermoplastic polyurethane (TPU) and poly(lactic acid) (PLA)-and BaTiO-SiC was fabricated. BaTiO particles were used to improve the dielectric properties of the composite materials, whereas SiC was used to enhance thermal conductivity without altering the dielectric properties; notably, SiC has a good dielectric constant. The surfaces of the filler particles, BaTiO and SiC particles, were activated; BaTiO was treated with methylene diphenyl diisocyanate (MDI) and SiC's surface was subjected to calcination and acid treatment, and hybrid fillers were prepared via solution mixing. The surface modifications were verified using Fourier transform infrared spectroscopy (the appearance of OH showed acid treatment of SiC, and the presence of NH, CH, and OH groups indicated the functionalization of BaTiO particles). After the extruded products were cooled and dried, the specimens were fabricated using minimolding. The thermal stability of the final composites showed improvement. The dielectric constant improved relative to the main matrix at constant and variable frequencies, being about fivefold for 40% BaTiO-SiC-TPU-PLA composites. Upon inclusion of 40 wt.% MDI functionalized BaTiO-SiC particles, an improvement of 232% in thermal conductivity was attained, in comparison to neat TPU-PLA blends.