Electromagnetic interference shielding efficiency of polyaniline mixtures and multilayer films

Electromagnetic interference shielding efficiency (SE) of the mixtures of p olyaniline(PAN) and: conducting powders such as silver (Ag), graphite, and carbon black is measured in the frequency range from 10 MHz to 1 GHz by usi ng ASTM D4935-89 technique. The measured SEs of the mixtures are from 20 dB to 50 dB, which agree with theoretical values obtained from a good-conduct or approximation. The SEs of the system increase with increasing DC conduct ivity. For the mixture of emeraldine base form of PAN and Ag powder doped w ith hydrochloric acid, the SE is similar to 46 dB with similar to 70 mu m t hickness. Chemical doping in PAN mixture samples induces the increase of th e SE. The model accounting for the increase of the SE in the mixture system is discussed. The effects of multilayer of PAN on the SE are presented.