Preparation And Properties Research Of Modified Carbon Nanutubes/Poly(vinylidene Fluoride) Composite Film

Poly(vinylidene fluoride)(PVDF),a ferroelectric polymer,which has unique piezoelectricity,ferroelectricity and thermoelectricity,making the application of PVDF based nanocomposites in the electromagnetic shielding field become a hot spot.For the composites composed of ferroelelctric polymer matrix,the dielectric properties are one of the important factors that affect the electromagnetic shielding effect.Due to unique structure,superior conducticity,light weight,effective microwave absorption and chemical stability,carbon nanotubes(CNTs)have attracted wide attention from researchers.Meanwhile,ferromagnetic materials have also been reported in electromagnetic shielding materials.However,combining conductive material and ferromagnetic material to improve the dielectric properties of polymer matrix has not been studied so far,and how to achieve uniform dispersion of nanofillers in the polymer matrix is a critical issue.Therefore,in this paper we combine CNTs with ferromagnetic materials to improve the dielectric properties of the PVDF matrix,and improve the diepersion of nano fillers in the PVDF matrix by surface modification.In this study,Fe3O4 nanoparticles were modified on the surface of CNTs by in situ hydrothermal synthesis,and the CNTs-Fe3O4@SiO2 nanohybrids were prepared by modifying the 15-20 nm thick SiO2 shell on the surface of nanoparticles by CTAB template.Then CNTs-Fe3O4@SiO2/PVDF composite films were prepared by mixing the nanohybrids with PVDF matrix use solution mixtion method.The morphology,crystallization,thermal properties,mechanical properties and dielectric properties were studied by scanning electron microscope(SEM),X-ray diffraction,Fourier transform infrared spectroscopy(FTIR),differential scanning calorimetry(DSC),thermogravimetric analysis(TG),dynamic thermomechanical analysis(DMA)and broadband dielectric spectrum test,respectively.The results show that the dispersion of CNTs-Fe3O4@SiO2 nanoparticles in PVDF is improved,and the nanohybrid have a significant effect on the crystallization of the composite film.The thermal properties,mechanical properties and dielectric properties of CNTs-Fe3O4@SiO2/PVDF composite film have been improved.The results could provide a new idea for the research of high dielectric PVDF based composites,which provides a theoretical basis for the development of electromagnetic shielding packaging in special fields such as microelectronics industry.