Thermal imidization and kinetic characterization of polyamide acid

Abstract

The imidization of Polyamide acid (PAA), as the main method to synthesis the organic polymer materials-Polyimide (PI) is influenced by pretreatment temperature. This paper focused on the thermal and kinetic characteristics of PAA imidization. Firstly, the effect of pretreatment temperature on the thermal behavior of PAA imidization was investigated by DSC and FTIR. It showed that the imidization of PAA was endothermic with 105.77 J g⁻¹ heat absorption in the range of 353.15–553.15 K. Secondly, the solvent peaks at 1359 cm⁻¹ and 1188 cm⁻¹ disappeared at pretreatment temperature 353.15 K, then the N–H peak of PAA at 3270 cm⁻¹ disappeared at 423.15 K and the C–N peak was enhanced at 473.15 K, indicating that the higher pretreatment temperature, the higher temperature range of PAA imidization. Finally, the kinetics characteristics of PAA imidization was studied. PAA imidization was divided into two stages, one was in the range of 353.15–423.15 K with the activation energy (E_a) of 131.15–200.07 kJ mol⁻¹, the other one was in the range of 423.15–473.15 K with E_a of 96.43–122.72 kJ mol⁻¹. The results indicated that the optimal PI film performance was achieved at a pretreatment temperature of 353.15 K.