Convenient manufacturing of gradient EVA/carbon nanostructure composite foams for green electromagnetic shielding

Construction of conductive polymer composites (CPCs) for green electromagnetic interference (EMI) shielding with efficient shielding effectiveness (SE) but low EM reflection is urgently needed. Though the introduction of cellular or gradient structures can effectively reduce EM reflection, most current methods for preparing gradient CPC foams are relatively complex and lack sufficient applicability for large-scale production. Herein, we demonstrate the convenient fabrication of gradient-structured EVA/carbon nanostructure (CNS) foams through chemical foaming of thermally molded EVA/CNS composites with gradient CNS construction. Compared to uniform EVA/CNS foams, lower R coefficient with an effective EMI SE of >20 dB was obtained for gradient EVA/CNS foams with 3 phr CNS, accompanied by an average green shielding index (g s ) of ∼2.8. This study provides a more feasible two-step process of thermal press molding and chemical foaming for mass manufacturing of gradient CPC foams with effective green EMI shielding characteristics.