Investigation of mechanical properties and dispersion in silica/Styrene Butadiene Rubber (SBR) nanocomposites: A ReaxFF molecular dynamics study

E Joseph and N Swaminathan, COMPUTATIONAL MATERIALS SCIENCE, 200, 110751 (2021).

DOI: 10.1016/j.commatsci.2021.110751

Various factors that affect nanoparticles' (NP) strength and dispersion in silica-Styrene Butadiene Rubber (SBR) nanocomposites are determined using ReaxFF molecular dynamics simulations. Factors such as the size of silica NP, type of Silane Coupling Agent (SCA), surface occupancy of SCA at the silica surface and spatial distribution of sulphur cross-links at a molecular scale are considered. Various parameters like peak normal traction, strength modulus, interface energy, radius of gyration, and distance between NP of different systems were monitored to determine which factors significantly influence NP's strength and dispersion. It was found that the strength increased with both the size and volume fraction of the NP. The size of the NP or the type of the SCA did not affect the dispersion at all. The dispersion of NP was found to depend on the surface occupancy of a given SCA significantly. Furthermore, it was observed that the introduction of sulphur cross-links farther from the NP increased the tensile strength of the nanocomposite than if they were closer to the NP. This result indicates that controlling the distribution of sulphur cross-links may significantly influence the strength of the nanocomposite.

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