Molecular Dynamics Simulation on the Interfacial Behavior of Over-Molded Hybrid Fiber Reinforced Thermoplastic Composites

Abstract

Hybrid fiber reinforced thermoplastic composites are receiving important attention in lightweight applications. The fabrication process of hybrid thermoplastic composites is that discontinuous fiber reinforced thermoplastics are injected onto the continuous fiber reinforced thermoplastics by over-molding techniques. The key issue during this process is to get a reliable interfacial bonding strength. To understand the bonding mechanism at the heterogeneous interface of hybrid thermoplastic composites which is difficult to obtain through experimental investigations, a series of molecular dynamic (MD) simulations were conducted in this paper. The influence of processing parameters on the interfacial characteristics, i.e., the distribution of interfacial high-density enrichment areas, radius of gyration, diffusion coefficient and interfacial energy, were investigated during the forming process of a heterogeneous interface. Simulation results reveal that some of molecule chains get across the interface and tangle with the molecules from the other layer, resulting in the penetration phenomenon near the interface zone. In addition, the melting temperature and injection pressure exhibit positive effects on the interfacial properties of hybrid composites. To further investigate the interfacial bonding strength and fracture mechanism of the heterogeneous interface, the uniaxial tensile and sliding simulations were performed. Results show that the non-bonded interaction energy plays a crucial role during the fracture process of heterogeneous interface. Meanwhile, the failure mode of the heterogeneous interface was demonstrated to evolve with the processing parameters.

Experimental investigation and molecular dynamics simulations of plasma treatment on the interface strength of overmolded hybrid fiber reinforced polypropylene composites

“…To assess the influence of plasma treatment on the interfacial strength of overmolded hybrid thermoplastic composites, tensile lap shear tests were carried on a universal testing machine (MTS CMT 4204, United States) according to ASTM D1002. As described in our previous work, [18] tensile lap shear samples with the dimensions shown in Figure 2 were obtained from overmolded F I G U R E 1 Schematic drawing of manufacturing process of hybrid thermoplastic composites T A B L E 1 Injection overmolding parameters for hybrid thermoplastic composites. [19] hybrid thermoplastic composites plate.…”

“…Regarding the injection overmolding process of hybrid thermoplastic composites, Jiang et al [ 18 ] reported that the physical–chemical interaction between CFRTs and injection molded part affects strongly the interfacial strength of overmolded hybrid thermoplastic composites. Thus, improving the interfacial strength of overmolded hybrid thermoplastic composites could be potentially achieved by plasma treatment on CFRTs laminate.…”

Elucidating the Interfacial Bonding Behavior of Over-Molded Hybrid Fiber Reinforced Polymer Composites: Experiment and Multiscale Numerical Simulation

“…Polymer/polymer interfaces have also been studied using molecular simulations. For example, the interface between PP/PA66, epoxy/epoxy interface, poly­(methyl methacrylate) (PMMA) substrates/cover sheet, and PVDF/epoxy resin have been well-illustrated using MD simulation to study the effect of temperature, pressure, and moisture content. However, no attempt has been made so far to evaluate the interfacial behavior of the PEEK-LMPAEK interface based on molecular simulations, which is the main objective of this work.…”

Mixed Mode Crack Propagation in Polymers Using a Discrete Lattice Method

“…The way in which the interaction elements are defined is what distinguishes each discrete model. Included in this category, it is important to mention: molecular dynamics models [ 36 , 37 , 38 , 39 ], focusing on the simulation of the movement of atoms and molecules through the definition of atomic potentials; peridynamic models [ 21 , 40 ], a nonlocal form of continuum mechanics in which the equation of motion is replaced by an integro-differential equation where spatial derivatives are removed, the peridynamic bonds transfer forces between connected points and their failure is used to establish damage at a certain point; and finally, the Lattice Models (LMs) [ 41 , 42 , 43 , 44 ], which are composed of one-dimensional mechanical elements that connect a set of nodes that may be regularly or irregularly distributed, being their main advantage the simplicity in the description of the propagation of cracks by eliminating the mechanical interaction between nodes.…”