Investigation Of The Interfacial Behavior Of Nanocomposite Reinforced By Carbon Nanotube Fiber And Graphene

Carbon nanotube(CNT) and graphene(GH) have attracted an extensive concern of scientists since they were found. The idea of space elevators and micro/nano robots gives the CNT and GH higher historic mission to innovate materials. In addition, the CNT and GH with their perfect physical properties will be promised reinforcements for composite materials. GH, a honeycomb-like sheet of carbon just one atom thick, likes a piece of “filter paper” having selective permeability for ions when ions pass through it. So it is expected to become a new type of ions sieve. Molecular dynamics method can not only accurately simulate the dynamic characteristics of large-scale atomic system in force or electric field but also show the trajectory of the dynamic system. Molecular dynamics simulation is of great significance for us to know the mechanical properties of the materials by observing the trajectory of the atoms. In this thesis, the interfacial behavior of CNT fiber/polyethylene(CNTF/PE) composite as well as graphene/polyethylene(GH/PE) composite, and the interaction between GH and ions in electric field were investigated by using molecular dynamics method. The main contents are as follows.(1) The interfacial behavior and fracture mechanism of CNTF/PE composite is investigated. The energy of the CNTF/PE composite system is conserved during the whole pull-out process. The structure parameters of CNT fiber(CNTF) play an important role in the interfacial shear strength of the CNTF/PE composite; Twisting weakens the bonding strength between the surrounding and the middle CNTs within CNTF; the interfacial shear strength of CNTF/PE composite is also reduced by twisting.(2) The interfacial fracture process of GH/PE composite is numerically simulated. The PE with a range of lattice structure is a kind of anisotropic material; the interfacial crack classified by the direction of crack growth can be divided into normal crack, shear crack and peeling crack, the interfacial bonding strength of these three kinds of crack are different. The interfacial bonding strength of normal crack is strongest, the peeling crack is secondary and the shear crack is weakest. The interfacial shear stress concentrations of these three kinds of crack are all at the crack tips, their failure process of the interface is reversible.(3) The interaction between GH and ions in electric field is discussed. Under the effect of strong electric field, the hydrogen ions and fluorine ions can easily pass through the GH, the phenomenon of C-C bonds broken does not occur in the process of the ions passing through the GH. In the role of weak current field, GH acting as a barrier, hydrogen ions and fluorine ions can not pass through it. Whether Hydrogen ions and fluorine ions can pass through the GH is also determined by the action time of the electric field. The shorter the time, the higher the voltage is needed when hydrogen ions and fluorine ions can pass through the GH. The longer the time, he lower the voltage is needed when hydrogen ions and fluorine ions can pass through the GH. This work is helpful to design of the GH-ion sieve.The significance of the present research work is intended to show the interfacial behavior of CNTF or GH composites and predict their interfacial strength, show the interaction behavior of GH and ions to provide theoretic support for the development of GH-ion sieve.