聚丙烯/氮化硼纳米片复合薄膜的制备及介电储能性能研究

Polypropylene (PP) films have been widely used in thin film capacitors and electrostatic energy storage devices. However, its further application are limited by low dielectric constant. In this paper, PP/BN nanocomposite films were prepared by doping low content hexagonal boron nitride (h-BN) two-dimensional nanosheets with PP as the matrix material to improve the dielectric constant of PP. One of the key factors is to control the two-phase interface to obtain a good dispersion of h-BN in PP and a close combination with the matrix. BNNSs with few-layer were prepared by sonication-assisted hydrolysis and exfoliation method, and then the organic PDA nanolayers were coated by dopamine self-polymerization. The morphology of BNNSs coated with PDA was characterized by TEM, XRD and FT-IR. The diameter of core-shell structure was about 150-200 nm, the minimum thickness was about 3 nm, and the average thickness of organic PDA shell was about 7 nm. PP based composite films with different contents of few-layer BNNSs@PDA were prepared by solution casting method. The dielectric properties and breakdown strength of the films were studied by means of SEM, voltage withstanding test equipment and impedance analyzer. The results showed that when the content of BNNSs@PDA was only 1wt%, the dielectric constant of the composite material increased to 5.62@1 kHz, the loss was only 0.006, and the theoretical energy storage density reached 7.42 J/cm³, which was 4.8 times higher than neat PP film. The above results show that BNNSs@PDA has a good binding force and compatibility with PP. The two-dimensional sheet structure with orientation distribution effectively hinders the expansion of the electrical trees under the external electric field, inhibits the transmission of carriers, and causes the interface polarization, thus effectively improving the dielectric and breakdown properties of the composite film.