以三种不同结构的聚酯铵盐前驱体为研究对象,采用傅里叶变换红外光谱研究前驱体的热环化过程,运用Gaussian 03程序计算得单体二胺的各原子电荷.结果表明:在170℃以前,前驱体热环化进行的较快,在170℃以后则明显减速;在热环化反应过程中,由于二胺结构不同,三类前驱体的热环化程度存在明显差异.与溶剂形成氢键的二胺的主要电子电荷数差异导致了前躯体热环化程度的不同,电荷数越大,其相应的前躯体环化程度越高.
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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