Enhancing electromagnetic interference shielding performance of polyester fabrics through composite polymer coating with metal oxides and expanded graphite

Radio frequency (RF) devices, in which use of high frequency electromagnetic waves, may cause electromagnetic interference (EMI), have been an essential part of the human being due to their large area applications especially as transmitters, receivers, computers, televisions, and mobile phones. However, the pollution caused by RF and/or EMI should not be underestimated. For this reason, studies have been carried out to develop shielding properties against EMI of various products, in particular of wearable fabrics. With this manner, in this study, composite polymer coated textiles were designed and produced by utilizing polyester base fabric, polyvinylidene fluoride coating polymer (matrix) and some additives (fillers) such as expanded graphite (E-GR), bismuth oxide (Bi₂O₃) and copper oxide micro/nano-particles. The experimental design on the preparation of the samples based on the unary, binary, and ternary combinations of the additives was created to investigate their combined effects on the EMI shielding performances. Samples were characterized by scanning electron microscopy, energy dispersive spectroscopy, fourier-transform infrared spectroscopy, and vector network analyzer. According to the results, it can be inferred that the fillers are homogeneously distributed along the all surface without a chemical interaction with the matrix of continuous and compact composite coatings. Among the samples, the highest EMI performance with 19 dB shielding effectiveness was recorded for the sample containing E-GR and Bi₂O₃ in which of the 98.74% electromagnetic signals were blocked along 8–12 GHz frequency range.