Dielectric properties of KH-SiO₂/PES/BMI-F51 composites

Abstract

KH-SiO2 was obtained by using 3-glycid-oxypropyl-trimethoxy-silane (KH-560) to modify nano-silica (nano-SiO2). KH-SiO2/PES/BMI-F51 multi-phase composite was prepared, the phenolic epoxy resin (F51) and bismaleimide (BMI) as the matrix, 4%(mass fraction, the same below) polyethe-rsulfone (PES) as toughening agent and different contents (0.5%-2.5%) of KH-SiO2 as modifier. The results of Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM) and transmission electron microscope (TEM) show that the surface modification of nano-SiO2 is favourable, the agglomeration tendency of nanoparticles is weakened, the size is decreased and the specific surface area is increased. Dielectric properties test displays that the dielectric constant of the material is decreased first and then increased with the increase of doping amount of KH-SiO2. There is no significant change in dielectric loss tangent, and the volume resistivity and breakdown strength are increased first and then decreased. The dielectric constant and dielectric loss tangent of composite reach 4.55 and 0.0029 at 10Hz, respectively, when the doping amount of KH-SiO2 is 1.5%. The volume resistivity and breakdown strength are 1.74×1014Ω·m and 29.11kV/mm, respectively, which are 68.9% and 35.9% higher than that of resin matrix.

Keywords

• bismaleimide
• polyethersulfone
• phenolic epoxy
• silica
• dielectric property