Effect of Particle Functionalization on Structural and Dielectric Properties of Flexible TPU/BaTiO3/MWCNTs Composite Films

Flexible, low-cost thermoplastic polyurethane (TPU) composite films with functionalized BaTiO3 (BT) and multiwall carbon nanotubes (MWCNTs) are prepared by solution casting and tested as dielectric materials. Different volume content loadings of BT filler (between 10 and 80 vol%) and 0.12 vol% of MWCNTs are applied. The effects of particle functionalization and BT content on the structural, mechanical, and energy storage properties are studied by Fourier infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), as well as puncture and dielectric measurements. It is found that the particle functionalization and BT content significantly affect the hydrogen bonding within the polymer matrix, and have a huge impact on the mechanical and dielectric properties. The optimal concentration (30 vol% of functionalized BT and 0.12 vol% of functionalized MWCNTs) giving the highest dielectric constant of 30.28 and dielectric breakdown strength of 42 kV mm−1 is determined.