Molecular Dynamics Investigation of the Compression and Stretching of Polymer Nano-composite Systems

NN Li and L Wang and Y Liu and HJ Liang, ACTA POLYMERICA SINICA, 1292-1300 (2014).

The tensile, compressive and equilibrium-state properties of polymer nano-composites (PNC) are studied using molecular dynamics (MD) with coarse-grained polymer-nanoparticle model. The influence of the size and the mass loading of the nanoparticles on PNC's mechanical properties, and the microscopic change of the cross-linked networks of PNC systems are investigated by the tensile and the compression tests of the PNC MD simulations. We find that nanoparticles of relatively smaller size reinforce the mechanical property more, when the surface area or the mass loading of nanoparticles of different sizes are kept still. Secondly, the mechanical property of PNC system increases while the increment becomes smaller, as the mass loading of nanoparticles increases; and there exists an optimised value of the mass loading of nanoparticles for enhancing the tensile property of PNC system. Most important, the microscopic polymer-polymer and polymer-NP crosslinked networks existing in PNC systems compete with each other, and affect the tensile and compression stress with different microscopic mechanisms. Additionally, the equilibration-state MD simulations of varying mass loading of nanoparticles illustrate that the ratio of respective microscopic cross-linked networks determines the mechanical properties of PNC systems, and the aggregation of the nanoparticles induced by overloading weakens such effects.

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