Two-dimensional scattering patterns and stress-strain relation of elongated clay nano composite gels: Molecular dynamics simulation analysis

K Hagita and Y Shudo and M Shibayama, POLYMER, 154, 62-79 (2018).

DOI: 10.1016/j.polymer.2018.08.047

To verify the structure-properties relation of elongated clay nanocomposite (NC) gels through two-dimensional scattering patterns (2DSPs), we performed coarse-grained molecular dynamics (CGMD) simulations of a bead-spring model of NC gels. In order to reproduce the 2DSP behavior, we modeled a clay particle as a disk-like aggregation of a large number of beads. In our model of polymer networks filled with the clays, we maintained the structural relations of the clays such as shape, size, and concentration, and emulated gelation processes through CGMD simulations. As results, the model with a scale map with 1 sigma = 2 nm, where s is the scale unit of CGMD simulations, succeeded in reproducing behaviors of stress-strain relations and 2DSPs. After our pseudo reaction processes with bonding between the ends of the polymers and between polymer ends and clays, uniaxial stretching CGMD simulations were performed. It is found that rapid increases in the estimated stress-strain relation for large stretching ratio were caused by the percolated network of the NC gel model with high NC concentration. We confirmed that the dependences of clay concentration and stretching ratio on 2DSP and stress were consistent with the small-angle neutron scattering experiments and tensile experiments, respectively.

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