Nanocomposite Foams of Polypropylene and Carbon Nanotubes: Preparation, Characterization, and Evaluation of their Performance as EMI Absorbers

Highly expanded nanocomposite foams of polypropylene and carbon nanotubes (PP/CNT) are formed using supercritical carbon dioxide (scCO(2)) technology. The foaming parameters (temperature, pressure) are investigated to establish their influence on the morphology of the resulting foams and their impact on the electrical conductivity. As promising electromagnetic-interference (EMI) absorbers, the EMI shielding performance of the foams is determined, and a preliminary relationship is established between foam morphology and the EMI shielding performance. The best candidates are highly expanded foams with a volume expansion of >25, containing 0.1 vol% CNTs; they are able to absorb more than 90% of the incident radiation between 25 and 40 GHz.