MD Simulation Of Interfacial Strength Of Carbon Nanotubes Reinforced Ultrahigh Molecular Weight Polyethylene Composite Fibers

Due to the perfect mechanical properties, carbon naotubes (CNTs) have been widely used in polymer nanocomposites as reinforcements to improve their mechanical performance in the past several decades. The reinforcement mechanism of the CNT-based polymer composites has become a key issue in the field of nanomaterials. Many researchers investigated the effect of CNTs on the mechanical properties of CNT/Polymer composites by experimental or simulation. Their results suggested there are two important factors for the improvement of mechanical properties of composites:one is the dispersion of CNTs in the matrix materials and the other is the interfacial strength between CNTs and polymer. In general, the interfacial strength of composites can be measured by the pull-out experiment. Since the diameter of CNT is at the nano scale, it is very difficult to directly measure the interfacial strength by experiments. Therefore, the molecular dynamic (MD) simulation has widely been used in these researches.In this thesis, the research focuses on the MD simulation of the interfacial strength of the CNT reinforced ultrahigh molecular weight polyethylene (UHMWPE) composite fibers. The free parallel simulation software, LAMMPS, is used to model the pull-out experiments. The interfacial strength are calculated by two methods, the conservation of the energy and the force-displacement method, respectively. The results reveal the effects of the length, diameter and the number of walls of CNTs on the interfacial strength. The advantages and disadvantages of these two methods are also discussed in the thesis. Lastly, the critical length of the shear stress transfer at the interface are calculated at different conditions based on the shear-lag model.