Fabrication And Characterization Of Cnt Buckypaper Reinforced Pmr-type Polyimide Composite

A PMR polyimide composite reinforced with CNT buckypaper, was fabricated by means of an two step process in this research project:impregnation and hot-compression. The PMR polyimide matrix resin was derived from 4,4'-methylenediamine (MDA), diethyl ester of 3,3',4,4'-oxydiphthalic (ODPE), monoethyl ester of cis-5-norbornene-endo-2,3-dicarboxylic acid (NA) and 4-(Phenylethynyl)phthalic anhydride (PEPA).CNT buckypaper were prepared by filtration method. The MWNTs were dispersed in methanol containing 0.2 vol:%Triton-X 100 by ultrasonic agitation. The solution was then vacuum filtered through a membrane filter with 0.2 mm pore size PTFE membrane filters to get buckypaper.The rheological properties as a function of solid content were investigated. Based on the cure reaction of the PMR type polyimide and the results of the rheological studies, an optimum two step fabricating method was established. In the first step, the buckypaper were impregnated with polyimide resin using vacuum filtration method at rising temperature followed by removing the solvent and pre-imidization. In the second step, the preforms were compressed by an optimized molding procedure.The internal structure of the composites were observed with a field emission scanning electron microscope. Needle shaped voids were generated in NA endcapped polyimide composite while the PEPA endcapped counterparts remain tight and voidless. The decomposition temperature and the temperature at 5% weight loss of the NA and PEPA endcapped composite are 413℃and 506℃, respectively.