The thermal stability of polyetherimide

A technique called bivariate fitting has been devised for obtaining kinetic parameters of thermal decomposition of polyetherimide from TGA data. In this way an apparent order of 5·33 was obtained, an apparent activation energy of 192kJ/mol, and a pre-exponential factor of 1·45 × 10¹²min⁻¹. Compared with other methods such as Friedman's⁵ and Ozawa's,⁶ this method was found to be a good approach to the solution of the kinetics of the decomposition. The products of the thermal degradation of the polymer were also analysed by ir, elemental analysis and pyrolysis/gas chromatography/mass spectrometry. A decomposition mechanism is suggested.