Deformation modeling of polyamide 6 and the effect of water content using molecular dynamics simulation
Polyamide 6 (PA6) shows significant water absorbability and hygroscopicity, which affect its mechanical properties such as Young’s modulus and yield strength, as water content enhances deformability. This study aims to investigate the effect of water molecules on the deformation behavior of PA6 and to elucidate the deformation mechanism at a molecular level. By using excluded volume map sampling method, we explored the possible incursion sites for water molecule absorption in the computational material cell. Using molecular dynamic simulations, we created the computational cell of PA6, and we applied mechanical loadings with and without the water molecule to determine the effect of water molecules on the deformation behavior. To investigate the fundamental reasons why water molecules enhance the deformability of PA6, we calculated the non-bonded potential energy of a pair of amide functional groups with and without the water molecule. The results reveal that water molecules decrease the interaction energy of the amide group, leading to macroscopic deformation. This study clarified the effect of water molecules on the deformation behavior of PA6, and it may be useful for predicting the mechanical deformation of PA6.
KeywordsPolyamide 6 Water Mechanical property Deformation Molecular dynamics simulation
This work is supported by the JSPS KAKENHI (grant no. 17 K06062) from the Japan Society for the Promotion of Science and by a research grant from The Suga Weathering Technology Foundation (no. 67).
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