Dielectric behavior and shielding properties of polyaniline composites

Intrinsically conducting polymers (ICP´s) and their blends with thermoplastics are very promising for applications in electromagnetic interference shielding (EMI). They can have relatively high conductivities and permittivities and these properties can be tuned easily from insulating to conducting states through chemical processes. Compared to metals, ICP´s are light, flexible and they can not only reflect but also absorb electromagnetic radiations. We report results obtained from polyaniline blends with thermoplastics in terms of variation of conductivity, permittivity and shielding effectiveness in function of the process of transformation of polymers, the mass fraction of polyaniline in the blends and the frequency in microwave and millimeter bands. The possibility to have low percolation threshold is very attractive to make materials with mechanical properties of the thermoplastics with the electronic properties of the ICP´s. The high value of shielding coefficient shows that ICP´s are efficient materials for such applications