Preparation And Characterization On Polyimide Foam And Polyimide Foam Reinforced With Carbon Fiber Honeycomb Material

In this paper,the preparation process and properties of polyimide foam and polyimide foam reinforced with carbon fiber honeycomb were investigated.First,polyimide precursor powder was yield using 3,3',4,4'-benzophenonetetracarboxylic dianhydride(BTDA),3,3',4,4'-biphenyltetracarboxylicdianhydride(BPDA),ethanoland4,4'-diaminodiphenylmethane(MDA)as raw materials.Then the powder was manufactured foam.Secondly,through using carbon fiber cloth,environment-friendly hot melt adhesive and polyamic acid solution as impregnated resin,carbon fiber honeycomb materials were prepared.Then polyimide foam reinforced with carbon fiber honeycomb was obtained by filling polyimide precursor powder into the carbon fiber honeycomb,foaming and applying post-treatment.And these products were characterized.The structures of BTDA and BPDA esterification product were analyzed by fourier transform infrared spectroscopy(FT-IR)and nuclear magnetic resonance spectroscopy(~1H-NMR).The esterification reaction time of BTDA and BPDA was determined as 1 h,and 12 h respectively.Through viewing the morphology of the polyimide precursor powder from scanning electron microscopy(SEM),it was found that the particle of the powder was a hollow microspheres with its dimension ranging from 0.5?m to 30?m.The foaming temperature of the polyimide precursor powder was determined by thermogravimetric analysis(TGA)in the range of 110~260?.The structure of polyimide foam was analyzed by FT-IR,which proved that the polyimide foam was completely imidized after high temperature treatment.The decomposition temperature of polyimide foam with weight loss of 5wt/%and 10wt/%was above 490?and 540?,respectively,which reveals the favorable thermal properties.The morphology and the properties of polyimide foam were characterized by scanning electron microscopy(SEM),TGA,limiting oxygen index(LOI)instrument,microcomputer controlled electronic universal testing machine and DR-1 thermal conductivity tester.The results show that with a decrease in molar ratio of BTDA and BPDA,the porosity,the compressive strength and the thermal conductivity of polyimide foam decrease and the limiting oxygen index increases.Polyimide foam shows excellent flame resistance and thermal stability.The compression performance and the insulation of polyimide foam reinforced with carbon fiber were tested by means of microcomputer controlled electronic universal testing machine and DR-1 thermal conductivity tester,and such results were compared to those of polyimide foam and carbon fiber honeycomb.The results were show the compression strength of the polyimide foam reinforced with carbon fiber honeycomb is much higher than that of the pure polyimide foam and the carbon fiber honeycomb.The compression strength of reinforced foam is 85 times higher than that of the pure polyimide foam and 35 times higher than that of the carbon fiber honeycomb,such results indicate that carbon fiber honeycomb and polyimide foam have a good synergistic effect.With the decrease in the cell size of carbon fiber honeycomb,the compressive strength of polyimide foam reinforced with carbon fiber honeycomb increases,and the recovery ability of polyimide foam reinforced with carbon fiber honeycomb gradually decreases.Meanwhile,the polyimide foam reinforced with carbon honeycomb has excellent insulation property.