[SY-H2] Study on viscoelastic behavior of natural rubber with multiscale approach
In this study, the viscoelastic behavior of natural rubber is investigated with the aid of a coarse-grained (CG) molecular dynamics (MD) simulation. It is challenging to understand the long-term nature of polymeric materials using a conventional MD simulation due to the inherent limitation in the time and length scale. To overcome the drawback in terms of scalability in time and length, the CG model can offer a way to assess the long-term physical behavior by substantially reducing a degree of freedoms with the implementation of bead particles which are equivalent to the specific group of atoms. To describe the inter- and intra-interactions between the beads consisting of the system, the iterative Boltzmann inversion (IBI) method is employed. As an important viscoelastic behavior of elastomer, the time-dependent shear relaxation modulus is calculated using the stress autocorrelation function. The dynamic modulus in a frequency domain is further studied with using the Fourier transformation. The influence of vulcanization and chain length of natural rubber is taken into account. Plus, the spherical shape of SiO2 nanoparticles are considered as filler materials, and the behavior of filler-rubber is also studied for varying filler loading conditions. With the present work, the viscoelastic nature of rubber is understood by employing CG MD simulations which can enhance the scale of computation in terms of length and time. Further, this work can be extended to examine more complex polymeric system regarding the long-term physical nature or thermodynamic property.