Study On The Preparation And Dielectric Properties Of Cnfs/pei Composite Film

In recent years, Polymer matrix composites have been extensivelydeveloped in the field of high-tech industries, such as: power electronics,aerospace, military and energy information, and are developing to thedirection of structure-integration materials. Polymer matrix compositescan have special dielectric properties, such as high or low dielectricconstant, and also have excellent mechanical strength and excellentmachinability performance, can be widely used in the area of thecapacitor and microelectronics.In this paper, CNFs was used as fillers, and polyetherimide (PEI)was used as resin matrix, using electrospinning and coating to prepareCNFs/PEI composite film.Research on the influence of solvent, solution concentration, airhumidity and CNFs to the electrospun process and morphology of PEIfiber. The results show that the solvents determine the spinnability of PEI,selected the NMP as the solvent, and produced the PEI fibrousmembranes for subsequent research. Air humidity seriously affects themorphology of PEI fibers, when the air humidity is40%, can get morphologically uniform PEI fibrous membranes. With the increase ofelectrospinning solution concentration, the average diameter increasesfrom400nm to3.25μm. CNFs seriously influence the morphology ofcomposite fibers, after ultrasonication, which can reduce the aspect ratio.The CNFs with small aspect ratio can significantly improve themorphology of CNFs/PEI fibers, and reduce the average diameter.With the addition of CNFs, the dielectric constant and mechanicalstrength of CNFs/PEI coating film can be significantly enhanced. Thedielectric constant of PEI fibers is very low, the range is1.1-1.62, andkeeping stable with frequency, the dielectric loss maintained at a very lowlevel. The solution concentration, the receiving method of the fibrousmembrane and hot-stretching influence the dielectric properties of PEIfibrous membrane. CNFs has little effect on the dielectric constant of PEIfibrous membrane, when the CNFs content is5wt%, the dielectricconstant can only rise to1.92. However the addition of CNFs caneffectively improve the thermal stability and dimensional stability, andcan also significantly enhance the mechanical strength of PEI fibrousmembrane.