Poly(butylene adipate-co-terephthalate)/carbon fiber foam bonded with continuous carbon fiber reinforced polypropylene prepregs for electromagnetic interference shielding

Construction of highly conductive layer on polymer foams is conducive to enhancing the electromagnetic interference (EMI) shielding performance. Herein, sandwich structures consisted of poly(butylene adipate-coterephthalate) (PBAT)/carbon fiber (CF) foam and continuous CF reinforced polypropylene prepregs were prepared. The prepregs and PBAT/CF composite film were first bonded by hot pressing, and then foamed using supercritical CO2. The morphology of fracture surfaces and peeling tests of the pressed samples demonstrated a good bonding in interfaces between prepregs and composites. Because the bonded prepregs hindered gas escape from PBAT/CF film, the cells of foams with prepregs were more uniform and denser. By adjusting the foaming temperature, pressure, and CF content, foams with cell size of 2.7-34.3 mu m, cell density of 4.4 x 107-7.3 x 1010 cells/cm3, and expansion ratio of 1.2-2.8 were achieved. Owing to the high conductivity of prepregs, sandwich structures also had an enhanced the EMI shielding performance. The EMI shielding effectiveness of the sandwich structure with a thickness of 0.7 mm and a 51 % decrease in density was 38.1 dB.