Themodification Of Polyether Imide And The Preparation Of Its Nanocomposites Microspheres

Polyetherimide(PEI)having excellent mechanical properties and heat resistance,it has been widely applied in the industrial field.However,compared with ordinary polymer materials,PEI has a higher processing temperature because of the higher glass transition temperature,and this make the enterprise spend much more money to produce it.In addition,In order to improve the thermal conductivity and antistatic ability of PEI,multi-walled carbon nanotubes(MWCNTs)are often used to modify PEI.But it is difficult to solve the problem of uniform dispersion of MWCNTs in the matrix by melt blending directly with MWCNTs and PEI in the extruder.Therefore,in order to reduce the production cost of PEI and improve the dispersibility of MWCNTs in PEI matrix,it is necessary to improve PEI synthesis and processing technology.We synthesized PEI with bisphenol A dianhydride,p-phenylenediamine and 4,4'-oxybisbenzenamine as raw materials,and prepared MWCNTs/PEI nanocomposites by microsphere.In the process of synthesizing PEI,to prepare bisphenol Adianhydride(BPADA)by a four step method which is the most important.First,sodium hydroxide is reacted with bisphenol A to prepare sodium salt of bisphenol A,sodium salt in the presence of catalyst and N-methyl-4-nitro phthalimide synthesis reaction of bisphenol A.Finally,the bisphenol A dianhydride was obtained by acidification and high temperature anhydride.Secondly,we will get the modified PEI with different proportions of p-phenylenediamine and 4,4'-oxybisbenzenamine which reacted with bisphenol A dianhydride.Thus,the modified PEI were prepared and the property of the PEI was characterized by thermo-gravimetric(TGA),Fourier transform infrared spectroscopy(FTIR),differential scanning calorimetry(DSC)and tensile performance test.The results show that the glass transition temperature of PEI after modification is 35 ?lower than that before modification,and still maintains high thermal stability and mechanical properties.Finally,MWCNTs/PEI nanocomposite microspheres were prepared under high speed stirring with polyvinylpyrrolidone as nucleating agent and surfactant,and water was used as precipitant.The morphology of the microspheres and the dispersion state of the carbon nanotubes was characterized by FTIR,scanning electron microscopy(SEM).The results show that the dispersion of carbon nanotubes in the MWCNTs/PEI nanocomposites is better than that in the direct melt blending process,and the addition of the carbonized carbon nanotubes is better than that of the direct melt blending process.And the content of volume electric conductivity of the percolation threshold was 1.0wt%and when the content of blending extrusion MWCNTs/PEI was 2.0wt%.