Carbon black silicone rubber blends as absorbing materials to reduce Electro Magnetic Interferences (EMI)

In this work the microwave absorbing properties of carbon black/silicone rubber blends were investigated in the frequency range 0.2+6.0 GHz, varying the carbon black contents. In particular, the permittivity of the samples was measured by a network analyzer and then the experimental data were fitted as function of microwave frequency and carbon black content, epsilon*=epsilon*(f,C). The reflection loss for a layer of blend attached on a metal plate, which is related to the shielding effectiveness, was simulated as function of frequencies and of layer thickness for some values of carbon black content, and the simulation results were summarized in contour plots. These plots can be used to select thickness and carbon black content necessary to achieve the desired shielding effectiveness for a given frequency.