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Molecular Dynamics Simulation of Polymer Nano-Composites Reinforced by Graphene Sheets under Impact Loading

khakbiz, Sadegh | 2016

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 48033 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Naghdabadi, Reza; Sohrabpour, Saeed
  7. Abstract:
  8. Mechanical properties such as Young's and bulk modulus and strength of material is improved by adding Nano fillers to polymer substrates. Hence by adding Nano fillers such as graphene and carbon nanotubes to polymer substrates it is possible to achieve better properties in resultant nano composites. The aim of this study is to investigate the improvement in polymer-based composites properties by adding graphene Nano fillers for shock absorption. In this study, molecular dynamics method is used to model the molecular behavior of the material. First, a sample cell that have the properties of the whole material, is modeled, then by applying impact loading in modeling software, the response of the material to impact loading is obtained. For more realistic modeling, graphene sheets are places in different places and angles among the polymer chains. The reactive force field has been used in this study. First by using the Hugoniostat method, the impact in steady state conditions was modeled and then, in order to validate the modeling, non-equilibrium method was used. The results show that by adding 1, 3 and 5 weight percent of graphene to the polymer substrate, Young's modulus increases 10, 41 and 59 percent, respectively. Also, in the impact loading, adding Nano fillers reduces volume changes in impact steady state conditions. But the positive effect of this Nano fillers in shock absorption, is higher for more pressure. The results showed that the higher density of Poly Methyl Methacrylate compared to Polyethylene, leads to better protection of graphene structure in the sheet state, and hence leads to better resistance of this sheet to volume changes. The results of applying impact to polystyrene, shows the reduction of volume changes to values lower than the corresponding ones for polyethylene in higher pressures. In addition, the ratio of volume changes caused by impact in Styrene, is always less than that of Polymethyl methacrylate
  9. Keywords:
  10. Nanocomposite ; Graphene ; Impact Loading ; Molecular Dynamic Simulation ; Reinforced Polymer

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