Preparation and Characterization of PU/PET Matrix Gradient Composites with Microwave-Absorbing Function

In the field of microwave-absorbing materials, functional powder has always been the focus of research. In order to fabricate lightweight and flexible garment materials with microwave-absorbing function, the current work was carried out. Firstly, the general properties of polyurethane (PU) matrix composites reinforced with various microwave-absorbing powders were studied, and the carbon nanotubes (CNTs)/Fe3O4/PU film was proven to have the best general properties. Secondly, the needle-punched polyester (PET) nonwoven fabrics in 1 mm-thickness were impregnated into PU resin with the same composition of raw material as Fe3O4/CNTs/PU film, thereby the microwave-absorbing nonwovens with gradient structure were prepared. Moreover, the absorbing properties of the CNTs/Fe3O4/PU/PET gradient composites were tested and analyzed. Finally, the relationship between the mass ratio of CNTs and Fe3O4, and the microwave-absorbing properties was studied. The results show that the mass ratio of CNTs/Fe3O4 has a significant effect on the microwave-absorbing property of CNTs/Fe3O4/PU/PET. When the mass ratio of CNTs/Fe3O4 is 1:1, the prepared CNTs/Fe3O4/PU/PET gradient composite can achieve effective reflection loss in the range of more than 2 GHz in Ku-band (12-18 GHz), and the minimum reflection loss reaches -17.19 dB.