Study On Dielectric Properties Of Polyimide-based Composites

As a kind of energy storage device,dielectric capacitor has high power,safety and reliability and fast charging-discharging speed.For dielectric materials,dielectric properties of materials are very important factors.With the development of devices from the original large scale and complexity to the direction of simplification,miniaturization and lightweight,the dielectric properties are particularly criticalFerroelectric ceramics are widely used due to their excellent dielectric properties Traditional organic polymer dielectric materials can be widely used in various working environments owing to their high pressure resistance,good flexibility and high mechanical strength.In this paper,different ceramic materials with high dielectric properties were used as filler to disperse in the polymer matrix with good flexibility and processing performance by in-situ polymerization to form composite film materials with high dielectric properties,good flexibility and processing performance.On this basis,the effects of different contents and types of ceramic fillers on the phase structure and microstructure of polyimide-based composite films were investigated in detail,and the changes of dielectric properties and energy storage energy with filling mass fraction,frequency and temperature were further analyzedSodium niobate(NN)nanofiber was prepared by sol-gel method,and then NN fiber/PI nanocomposite film was prepared by in-situ polymerization after dopaminergic modification.The structure of the composite was analyzed by a series of tests and characterization,and the dielectric properties of the composite were systematically studied Thermogravimetric analysis showed that the prepared nanocomposite film had good thermal stability.For dielectric properties,at 100 kHz,the dielectric constant of the composite film reaches the maximum value of 5.79 when the fiber filling amount increases to 15 wt%,and the dielectric loss is about 0.012Potassium sodium niobate(KNN)fiber was prepared successfully by sol-gel method and electrospun.After the prepared fiber was etched by nitric acid solution,KNN fiber/PI nanocomposite film was prepared by in-situ polymerization method.The structure morphology and dielectric properties were studied by various characterization methods The results showed that the dielectric constant of the composite film reached the maximum value of 8.72 at 100 kHz,when the fiber filling content increased to 10 wt%,and the dielectric loss was about 0.003The(Sm0.5Nb0.5)0.02Ti0.98O2 ceramic particles with giant dielectric properties and low dielectric loss were prepared by solidstate sintering method,and then the(Sm0.5Nb0.5)0.02Ti0.98O2/polyimide composite film materials were prepared by in-situ polymerization.Its morphology,structure and dielectric properties were systematically studied by some characterization methods.The results show that the dielectric constant of composite film increases with the increase of the filling amount.At 100 kHz,the dielectric constant of composite film reached the maximum value of 12.30 when the filling amount was 40 wt%,and the dielectric loss was 0.014Polyimide is one of the organic insulation materials with the highest heat resistance grade,and it has good temperature stability.These composite film materials would be very suitable for the field that needs to work at high temperature.