Three-layered PBAT/CNTs composite foams prepared by supercritical CO2 foaming for electromagnetic interference shielding

Plastic pollution and electromagnetic radiation cause serious environmental problems. Herein, biodegradable poly(butylene adipate-co-terephthalate) (PBAT) and carbon nanotubes (CNTs) composite foams with three-layered structure for electromagnetic interference (EMI) shielding application were prepared by an environmentally friendly supercritical CO2 foaming method. For the CNTs content of 4.9 vol%, the EMI shielding efficiency (SE) of three-layered composite was 23.4 dB, which was improved by 125 % compared with that of single-layered composite with a CNTs content of 4.7 vol% owing to high conductivity in skin layer and multiple reflection between interfaces. The CNTs content in core has little effect on the EMI SE when the CNTs content in skin was 16 wt%. After foaming, SE values slightly decreased due to a decreased volume content of CNTs. However, considering the decreased density of foam, the specific EMI SE was improved by 26.2% after foaming when the CNTs content was 16 wt% in skin and 0 in core. This work provided a facile and green method for preparing lightweight EMI shielding materials.