Flexible and High-Performance\nElectromagnetic Shielding\nMaterials from Waste Polyurethane Foams

Abstract

In the modern society, polymer composites utilizing various\nwastes\nfor electromagnetic interference (EMI) shielding are of great economic\nand social significance. Herein, we report that waste polyurethane\nfoams (WPUF) can be facilely converted into high-performance EMI shielding\nmaterials via surface coating of carbon nanotubes followed by hot\npressing. The merit of this work lies in the novel skin-core segregated\nstructure from the complete three-dimensional skeleton of WPUF, which\nis well retained after compression molding. The uniform distribution\nof multiwalled carbon nanotubes (MWCNTs) on the polyurethane skeleton\nsurface assisted by cellulose nanofibers (CNFs) provides the material\nwith remarkable electrical conductivity, leading to excellent EMI\nshielding properties. The resultant composite (WPUF-MC) achieves a\nhigh EMI shielding effectiveness (SE) of 63.2 dB at a low loading\nof MWCNTs (6.6 wt %), far surpassing the values for many early reported\nshielding materials of this kind. Moreover, the WPUF-MC also exhibits\nsufficient flexibility and reliable EMI shielding performance. Even\nif bent or twisted 1000 times, it can still maintain EMI SE at a fairly\nhigh level. This work not only offers an effective strategy for high-value\nutilization of WPUF but also may expand the application potential\nof flexible shielding materials.