Electromagnetic interference shielding effect of nanocomposites with carbon nanotube and shape memory polymer

The nanocomposites with carbon nanotubes (CNTs) and shape memory polymer (SMP) were developed for electrical applications. The specimens with different CNTs weight fractions were prepared. Their electrical resistivities and electromagnetic interference (EMI) shielding effectiveness (SE) were investigated. The electrical resistivity was examined by four-probe method at different testing temperatures of 25, 35, 45, 55 and 65 degrees C around glass transfer temperature (T-g). As a result, for the developed nanocomposites, even lower weight fraction of CNTs could achieve a high level of conductivity and a low percolation threshold for CNTs content was confirmed. The electrical resistivity for the developed nanocomposites is dependant obviously on temperature with a linear relation like metals. The interconnected conducting network was formed more easily than other fillers. For the EMI SE measurements, a near-field antenna measurement system was used. The experiments to evaluate EMI SE were carried out in three different frequency bands, 8-26.5 GHz (K band), 33-50 GHz (Q band) and 50-75 GHz (V band). The EMI SE of CNT/SMP nanocomposites have a strong dependence of carbon nanotube content and the specimen thickness at all of three frequency bands. The higher frequency, the larger EMI SE. For the materials with 5.5 wt% VGCFs both experiment and analysis will agree well, and theoretical prediction proposed for EMI SE may be useful. (C) 2007 Published by Elsevier Ltd.