Cobalt Ferrite/Polyetherimide Composites as Thermally Stable Materials for Electromagnetic Interference Shielding Uses

The progress of the automated industry has introduced many benefits in our daily life, but it also produces undesired electromagnetic interference (EMI) that distresses the end-users and functionality of electronic devices. This article develops new composites based on a polyetherimide (PEI) matrix and cobalt ferrite (CoFe2O4) nanofiller (10-50 wt%) by mixing inorganic phase in the poly(amic acid) solution, followed by film casting and controlled heating, to acquire the corresponding imide structure. The composites were designed to contain both electric and magnetic dipole sources by including highly polarizable groups (phenyls, ethers, -CN) in the PEI structure and by loading this matrix with magnetic nanoparticles, respectively. The films exhibited high thermal stability, having the temperature at which decomposition begins in the interval of 450-487 degrees C. Magnetic analyses indicated a saturation magnetization, coercitive force, and magnetic remanence of 27.9 emu g(-1), 705 Oe, and 9.57 emu g(-1), respectively, for the PEI/CoFe2O4 50 wt%. Electrical measurements evidenced an increase in the conductivity from 4.42 10(-9) S/cm for the neat PEI to 1.70 10(-8) S/cm for PEI/CoFe2O4 50 wt% at 1 MHz. The subglass gamma- and beta-relaxations, primary relaxation, and conductivity relaxation were also examined depending on the nanofiller content. These novel composites are investigated from the point of view of their EMI shielding properties, showing that they are capable of attenuating the electric and magnetic parts of electromagnetic waves.

Automated summary

This article presents the development of new composites based on a PEI matrix and CoFe2O4 nanoparticles. These composites exhibit high thermal stability and increased conductivity compared to pure PEI. The composites also show potential for attenuating the electric and magnetic parts of electromagnetic waves, making them suitable for EMI shielding applications.