[SY-H11] Symposium H-11

[SY-H11] Some Positive Aspect of Structural Defects in Graphene/Polymer Nanocomposites Studied by Abinitio,Molecular Dynamics, and Continuum Approaches

^○Seunghwa Yang¹, Janghyuk Moon¹, Maenghyo Cho² (1.School of Energy Systems Engineering, Chung-Ang University, Korea, 2.School of Mechanical and Aerospace Engineering, Seoul National University, Korea)

In this study, we reveal some positive aspect of the intrinsic defect commonly observed in two dimensional nanocarbon structure of graphene as a multifunctional reinforcement. Among the intrinsic defects commonly observed in graphene, we focus on the crystallographic defect of the Thrower-Tone-Wales (TSW) defect. Since the formation of the TSW defects in graphene involves 90 degree of rotation of the two covalently bonded neighboring carbon atoms and the resultant change in electron density, we firstly adopt the density functional theory to investigate the adhesion characteristics of the carbon atoms in TSW defect to the to the polypropylene (PP) monomers. In order to observe the effect of the arbitrarily generated TSW defect on representative volume element level mechanical properties, we modeled transversely isotropic molecular unit cell model of single layer graphene reinforced PP nanocomposites. The stress-strain curves in tension and shear are predicted from a constant strain rate ensemble simulation at below the glass transition temperature of the PP matrix and at the atmospheric pressure. At the same time, the mechanical properties of single layer graphene embedding the TSW defect is studied using the same ensemble simulations. To correlate the locally rippled configuration of the TSW defected sites to the macroscopic stress-strain relation, we analyzed the surface roughness of the graphene according to the density of TSW defects. Finally, a multiphase micromechanics model incorporating the weakened interface between graphene and PP matrix is applied to study the stress-strain relation of poly-dispersed nanocomposites with random graphene orientation. The two rivalling effects of the degradation of the graphene and improvement of the interfacial shear load transfer are evaluated from parametric studies on the effect of the aspect ratio and the volume fraction of the defected graphene on overall stress-strain relation of poly-dispersed nanocomposites.
This research is supported by a Basic Science Research Program grant (15-113-701-010) through the Agency for Defense Development of Korea