On the thermal stability of some aromatic-aliphatic polyimides

Aromatic-aliphatic polyimides were synthesized and their thermal decomposition process was investigated. Thermal degradation processes had been undertaken by dynamic thermogravimetry in nitrogen atmosphere, up to 700 °C. Comparative thermal stability studies of the samples were also undertaken. Evolved gases analyses were conducted by using a coupling to a quadrupole mass spectrometer and a Fourier transform infrared spectrophotometer equipped with external modulus for gas analysis. Kinetic study was conducted by applying Flynn-Wall-Ozawa, Friedman and non-linear regression methods. Kinetic parameters values decreased with the increase in conversion degree values, suggesting the occurrence of a change in rate determining step.