The Surface Treatment Of MWNTs And Its Influence On Mechanical Properties Thermal Performance And Electric Performance Of Polyimide Film

With the development of all industries based on electronic field, polyimide(PI) film which has high insulation, heat and cold resistance, high strength, etc.has been widely used in F, H class motors, transformers, electrical insulation,flexible printed circuit boards, mobile phones, computers and other electrical andelectronic industry. However, with the development of miniaturization ofmicroelectronic devices, higher performance requirements for PI films has beenalso put forward. in recent years, with the launching of studies on PI filmmodified by inorganic nanoparticles, PI films modified by MWNTs has madesome Results, But it mainly focuses on the corona-resistant and resistant tobreakdown performance of polymer material, while the testing and analysis oftwo-phase composite system’s overall performance is relatively rare, Carbonnanotubes (MWNTs) as an one-dimensional long fibrous material, not onlyhaving excellent electrical properties, but also having high strength and heatresistance, which is added to the PI matrix, will inevitably force mechanical,electrical, thermal properties of PI films. However, surface energy of MWNTs islarge, and reunite each other easily, hardly dispersed in the matrix, thus limitingit to play its role of long fibers. Therefore, we use different methods for surfacetreatment of MWNTs, and then added MWNTs treated to PI matrix for the studyof the impact of MWNTs treated on mechanical, electrical and thermal propertiesof the films.In this paper, using pyromellitic dianhydride (PMDA) and4,4’-diaminodiphenyl ether (ODA) as raw material, mixing functional MWNTs andmonomer by situ polymerization, then MWNTs/PAA hybrid glue was prepared,Films was made by industrial casting method on glass plate firstly, then throuth thermal imidization. many factors affect functionalized effect of MWNTs, wetreated MWNTs by mixed acid and fenton, finding the factors of functionalizedeffect affecting MWNTs, studying the affect of functionalized MWNTs onmechanical, electrical, thermal properties of PI films. SEM results showed:MWNTs entanglement after ultrasound treatment were solved, MWNTs by mixedacid treatment for4h,8h,12h were chopped, and entanglement phenomenonreduced significantly, length distribution of MWNTs was also smaller, can bemore evenly dispersed in ethanol solution; FTIR test results showed: the carboxyland hydroxyl functional groups were grafted on MWNTs surface after acidtreatment, hydroxyl functional groups were grafted on MWNTs surface afterfenton treatment; XRD results showed: MWNTs after mixed acid treatmentimproved the order degree of PI films molecule. MWNTs/PI composite filmsstretched data showed: tensile strength of mixed acid treated8h of MWNTs/PIcomposite films was greater than the mixed acid treated4h and12h of MWNTs/PI composite films, tensile strength of MWNTs treated by fenton/PI film wasgreater than the mixed acid treated MWNTs/PI composite films, moreover thedielectric constant and dielectric loss was relatively low, the increasing ondielectric strength of the films were more obvious; When the doping amout ofMWNTs were2.0wt%, the mixed acid treated MWNTs/PI composite films andfenton treated MWNTs/PI composite film were still showing good insulation.fenton balanced the tensile properties and dielectric properties of composite filmsbetter. Thermal property test results showed: under the experimental additionamount, addition of functionalized MWNTs had little impacts on thermaldecomposition temperature of PI films.