FOURIER-TRANSFORM INFRARED-SPECTROSCOPY ON THE THERMOOXIDATIVE DEGRADATION OF POLYBENZIMIDAZOLE AND OF A POLYBENZIMIDAZOLE POLYETHERIMIDE BLEND

The thermo-oxidative degradation of the polybenzimidazole material, poly[(2,2'-m-phenylene)-5,5'-bibenzimidazole] (PBI), and of a blend of PBI with the polyetherimide, poly[2,2'-bis(3,4-dicarboxyphenoxy) phenylpropane-2-phenylene bisimide] (Ultem 1000), was investigated by Fourier transform infra-red (FTi.r.) spectroscopy. An experimental protocol and the necessary instrumentation were developed for real-time monitoring of the molecular changes occurring during the process. The spectroscopic data provided information about the mechanism and the kinetics of the thermo-oxidative degradation in its early stages. The FTi.r. spectra of the PBI/Ultem 1000 blend were analysed by subtraction spectroscopy, and the application of this technique allowed us to selectively follow the fate of the two components in the blend. No chemical interaction between PBI and Ultem 1000 was detectable by FTi.r. spectroscopy during the degradation process.