Synthesis and curing process of TMA-MDI polyamide-imides

Abstract

The influence of molecular ratio of monomers, reaction time, reaction temperature and solid content on the molecular weight of polyamide imides(PAI), heating rate, temperature and time on tensile properties of PAI film was investigated in detail. The results showed that when monomer molar ratio (MDI: TMA)R >1, PAI is an isocyanate terminated, intrinsic viscosity increases with the increase of R, reaches maximum value at R=1.06, then it decreases obviously. Contrarily, when R <1, PAI is terminated with anhydride, intrinsic viscosity increases with the decrease of R, its maximum value at R= 0.97, then it decreases with the decrease of R. The relation between intrinsic viscosityof PAI and reaction temperature, reaction time, solid content all follows the parabolic law. The optimal reaction temperature,reaction time, solid content is 140°C, 120 min, 30%. Therefore, the best synthesis process of the PAI is reacting for 120 min at 140°C when 30% solid content and R=1.06. Tensile strength and elongation increase with the increase of heating rate, curing temperature and curing time, after peak value, they decrease with the increase of heating rate, curing temperature andcuring time. The best curing process of the PAI is curing for 2h at 260°C and heating rate 100°C/h.