Carbon Nanotubes/Polyimide Nanocomposite

As the technology develops and the society advances,the demand for Polyimide(PI)has increased and the quantity requirements have risen up.There has been more attention paid to PI as its performance being improved,new function being developed and new adaptations being more widely used through different modification methods.In this paper,the biphenyl polyimide was prepared through the two-step method,using 3,3',4,4'-biphenyl dianhydride(BPDA)and 4,4'-diaminodiphenyl ether(ODA)as raw materials,N,N'-dimethylacetamide(DMAc)as solvent.Carboxylated multi-walled carbon nanotubes(MWNTs)as reinforced phase,A series of MWNTs/PI composites with different content of carbon nanotubes were prepared by ultrasonic dispersion-in situ polymerization.4-Phenylethynyl(4-PEPA)terminated polyimide composites were also prepared.The structure,the morphology,the glass transition temperatures(Tg),thermostability and electrical insulation property were characterized by Fourier Transform Infrared Analysis(FT-IR),Scanning Electron Microscopy(SEM),Differential Scanning Calorimetry(DSC),Dynamic Mechanical Thermal Analyzer(DMA),Thermogravimetic Analysis(TGA)and High Resistance Tester,respectively.The physical and mechanical properties were also tested.The results indicated that the modified MWNTs were dispersed homogeneously in the polyimide matrix by ultrasonica treatment.The Tg and thermal stability of the MWNTs/PI composites increased with the increasing of MWNTs content,but when the MWNTs content was further increased,the Tg and thermal stability decreased.Meanwhile,the composites could have a certain conductivity by introduction of MWNTs into PI matrix.The tensile strength and elongation at break were all increased with the increasing of MWNTs content,which reflected the enhancement effect of the MWNTs.