Abstract: This paper studied the addition of microspheres on the conductivity, dielectric properties and electromagnetic shielding properties of carbon black/epoxy resin composites. When the carbon black volume fraction was 36vol%, the volume resistivity value reach the lowest value of about 169Ω·cm, the density of the composite was 120kg/m³, the maximum shielding effectiveness was 12.18dB, the maximum dielectric loss was 0.48, and the maximum imaginary part of the dielectric constant was 12.58. After adding microspheres. When the carbon black volume fraction was 36vol%, the volume resistivity value was 121.1Ω·cm, the density of the composite was 80kg/m³, at the corresponding frequency, the maximum shielding effectiveness was 15.44dB, the maximum dielectric loss was 1.46, and the maximum imaginary part of the dielectric constant was 20.52. Therefore, the addtion of the microspheres not only reduce the density of the material, but also greatly improve the conductivity, dielectric properties and shielding properties of the carbon/epoxy composite.

Key words: carbon black, PS foam microspheres, conductivity, dielectric, EMI