Mechanical modeling for evaluation of effects of molecular chain structure and crystallinity on mechanical behavior of polyamide

Abstract

Polyamide (PA) is a semi-crystalline polymer in which main chain is configured by repeating units of amide bonds (-NHCO-). The strength of PA is achieved by intermolecular hydrogen bond between hydrogen and oxygen atoms of amide bonds. In this study, the effects of the density of amide group, crystallinity were investigated by uniaxial tensile tests of commercial PA6 and PA-MXD10. Furthermore, the time-dependent nonlinear mechanical model based on the unfixed MCN model was proposed to predict the mechanical behavior of PAs with different crystallinities. From experimental results, the maximum stress was proportional to tensile rate, and the stress-strain curves of the PAs with small crystallinity showed the sharp drop after the maximum stress. In contrast, the gradual change in the stress can be observed around the maximum stress of the PAs with large crystallinity. Simulation results indicated that the modified unfixed MCN model can predict the mechanical behavior of PAs with different crystallinities.