Effect of Crystallinity on Relaxation Losses in Polyimide R-BAPS Films
The effect of the degree of crystallinity on relaxation processes in poly((4,4'-bis(4-aminophenoxy) biphenyl)imido-1,3-bis(3,3'-4,4'-dicarboxyphenoxy)benzene) films is studied by thermoactivation spectroscopy and dynamic mechanical analysis. Using thermoactivation spectroscopy, it shown that the β transition is caused by the dipole-group relaxation of polyimide, the β' transition is related to the breakdown of spatial charge, and the α transition is due to the dipole segment relaxation. The dynamic mechanical analysis data correlate with the results of thermoactivation spectroscopy studies. The activation energies of the relaxation processes are calculated. It is shown that the β- and β'-relaxation peaks shift toward higher temperatures with an increase in the degree of crystallinity of polyimide R-BAPS.
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