Comparative analysis of the structure and properties of high-temperature resistant polyamide PA6T/66 and PA5T/56

PA6T/66 and PA5T/56 with stable molecular weight and molecular weight distribution were prepared by one-step polymerization. The relationship between the structure and physicochemical properties of two kinds of polyamide samples was analyzed by software analysis and instrument test. The results show that the hydrogen bond between molecular chains has a significant effect on the properties of the materials. From the microscopic point of view, the mechanical properties of PA5T/56 molecular model were generally better than those of PA6T/66 molecular model because the hydrogen bond was not considered. At the macro level, the result was just the opposite because of the hydrogen bonds between the molecular chains. The Gibbs free energy of PA5T/56 dehydration condensation reaction was larger, indicating that the polymerization rate was faster, which was consistent with the actual situation. PA6T/66 belongs to the triclinic α crystal system, PA5T/56 belongs to the hexagonal γ crystal system, PA6T/66 T_g = 105.50℃, T_c = 257.34℃, T_m = 295.74℃, the ΔG_PA6T/66 and ΔG_PA5T/56 = 36.84 kJ/mol and 34.27 kJ/mol respectively indicate that the heat resistance and thermal properties of PA6T/66 were better than those of PA5T/56.