Abstract：Poly(ester-amine salt)s(PEAS) precursor's cycloimidization to polyimide was important one of two-step polyimide foam plastics producing method.Three different and closely related PEAS were prepared,their thermal cycloimidization to the corresponding imides form was investigated by Fourier transform infrared spectroscopy(FTIR) analysis under isothermal conditions at eight different temperatures,for 30min respectively.The electric charge of different main atoms forming hydrogen bond with solvents was achieved through Gaussian 03 program.The results showed that the degree of cycloimidization of PEAS to polyimide had been calculated from their FTIR spectra.Cycloimidization occured at faster rate before 170℃,after that,this processes decreased gradually.Depending on the nature of diamine,the cycloimidization degree of containing electron with-drawing group like sulfone(PEAS3) and ether(PEAS2) in the diamine was somewhat higher compared with those of PEAS1.The higher electric charges of main atoms of diamine leaded to the higher cycloimidization degree of PEAS precursor.
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