Abstract
Polyamide is a semi-crystalline polymer with different nano-micro structures and macroscopic mechanical properties depending on thermal history. In this study, polyamide specimens were prepared under isothermal and annealing conditions. The nano-micro structure was evaluated by wide angle X-ray scattering, small angle X-ray scattering (SAXS), Differential Scanning Calorimetry, and polarized light microscopy. The SAXS measurement revealed the difference of nano-micro structures in PA6 with different thermal histories. The macroscopic mechanical properties were measured by uniaxial tensile tests. Based on the measured results, the relationship between nano-micro structure and macroscopic deformation behavior was discussed and evaluated. Under the high-temperature isothermal condition where spherulites are formed, a tendency to fracture was observed without stretching after the yield stress. On the other hand, under the annealing conditions where crystal morphologies other than spherulites were formed, stretching was observed until the late stage of deformation even after the yield stress. The relationship between the lamella thickness obtained from the SAXS measurement and the maximum stress obtained from the tensile test was confirmed to be correlated under both the isothermal and annealing conditions for PA6. On the other hand, the relationship between the maximum stress and the lamella thickness of PAMXD10 was represented to be different from that of PA6.
