Thermal and thermo-oxidative stability and probable degradation mechanism of some polyetherimides

• Aromatic polyetherimides were synthesized.
• Thermal stability in air and helium was investigated.
• The influence of structure on the thermal degradation mechanism of the polymers was evidenced.

This study assesses the thermal and thermo-oxidative stability and establishes the degradation mechanism for five aromatic polyetherimides, by simultaneous mass spectrometry and Fourier transform infrared spectroscopy of off-gases from thermogravimetric analyzer in two working atmospheres: air and helium. Aromatic polyetherimides were synthesized starting from 4,4′-(4,4′-isopropylidenediphenoxy)bis(phthalic anhydride) and five aromatic diamines, three of them containing 1,3,4-oxadiazole ring. The study establishes the influence of the structure and of the working atmosphere on the thermal stability and the start mechanism of thermal degradation. Moreover, it determines the main decomposition products both in inert atmosphere (helium) and in air.