Zero-temperature-coefficient of capacitance in BaTiO3/PI composite films using paraffin as barrier layer

Firstly, the BaTiO 3 nanoparticles were coated with a layer of paraffin, forming a core shell structure. Then, as-prepared paraffin@BaTiO 3 nanofillers were directly blended with polyimide (PI) prepolymer to fabricate paraffin@BaTiO 3 /PI composite films. The microstructure, thermal, and dielectric properties were investigated in detail. The surface-modified paraffin@BaTiO 3 nanoparticles exhibited a typical core shell structure with uniform and complete coverage. The char yield of the composite film with 10 wt% paraffin@BaTiO 3 increased from 56.40% to 70.73%. It is obvious that the paraffin@BaTiO 3 nanofillers have a positive effect on ablative performance of the composite film. Compared with pure PI, the ε r of paraffin@BaTiO 3 /PI composites with 40% mass fraction increased from 3.41 to 9.35 (1 kHz). The tanδ of paraffin@BaTiO 3 /PI composites was just 0.0065 (1 kHz) when the filler loading was 40 wt%. Temperature dependency of the permittivity of the composites reveals a zero-temperature-coefficient from 80°C to 180°C.