Effect of in situ fibrillation on polyethylene/poly(ethylene terephthalate)/multiwalled carbon nanotube electromagnetic shielding foams

In this study, polyethylene (PP)/polyethylene terephthalate (PET)/multiwalled carbon nanotube (MWCNT) nanocomposites with nanofibrillary structure were processed by hot drawing‐assisted extrusion technology, and nonfoaming and microfoaming samples were processed by injection molding machine. Scanning electron microscope micrographs showed that when PET content was 2.5 wt%, PET fibers had a larger aspect ratio, which brought an outstanding promotion on microfoaming of PP matrix, and further details were provided by DSC and rheology analysis. When foaming sample loaded with 2.5 wt% PET and 3 wt% MWCNT, the best shielding effectiveness achieved 29.91 dB·cm3·g−1 in the test frequency range about 8.2–12.4 GHz. The results proved that the introduction of PET fibers optimized the microfoaming effect, and the uniform cell structure promoted the MWCNT dispersion and internal reflection of electromagnetic wave. Therefore, the shielding property is absorption‐dominated type and meets the requirements of lightweight and ultraefficient shielding demand of industry. Experimental consideration.