Abstract Multilayer graphene sheets (MLGSs) are promising nano-reinforcements that can effectively enhance the properties of polymer matrices. Despite many studies on MLGSs-reinforced polymer nanocomposites, the effect of wrinkles formed in MLGSs on the reinforcement effect and the viscoelastic properties of polymer nanocomposites has remained unknown. In this study, building upon previously developed coarse-grained models of MLGSs and poly(methyl methacrylate) coupled with molecular dynamics simulations, we have systematically investigated nanocomposites with different numbers of graphene layers and various wrinkle configurations. We find that with decreasing degree of waviness and increasing numbers of layers, the elastic modulus of the nanocomposites increases. Interestingly, we observe a sudden stress drop during shear deformation of certain wrinkled MLGSs-reinforced nanocomposites. We further conduct small amplitude oscillatory shear simulations on these nanocomposites and find that the nanocomposites with these specific wrinkle configurations also show peculiarly large loss tangents, indicating an increasing capability of energy dissipation. These behaviors are attributed to the activation of the interlayer sliding among these wrinkled MLGSs, as their interlayer shear strengths are indeed lower than flat MLGSs measured by steered molecular dynamics technique. Our study demonstrates that the viscoelastic properties and deformation mechanisms of polymer nanocomposites can be tuned through MLGS wrinkle engineering.
#1Yangchao Liao(NDSU: North Dakota State University)H-Index: 1
#2Zhaofan Li(NDSU: North Dakota State University)H-Index: 3
Last. Wenjie Xia(NDSU: North Dakota State University)H-Index: 20
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Abstract Understanding the complex structural behaviors of crumpled graphene at a fundamental level is of critical importance in various engineering and technological applications. Here, we present a coarse-grained molecular dynamics (CG-MD) study for investigating structural behaviors of graphene sheets having varying sizes (or masses) during the crumpling process. The simulation results reveal that larger size graphene sheets at the initial two-dimension (2D) state tends to become more self-ad...
Last. Xiaohu Yao(SCUT: South China University of Technology)H-Index: 14
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Abstract Incorporating graphene nanosheets into a polymer matrix is a promising way to utilize the remarkable electronic, thermal, and mechanical properties of graphene. However, the underlying mechanisms near the graphene-polymer interface remain poorly understood. In this study, we employ coarse-grained molecular dynamics (MD) simulations to investigate the nanoscale mechanisms present in graphene-reinforced polycarbonate (GRPC) nanocomposites and the effect of those mechanisms on GRPC’s mecha...
Two-dimensional materials such as graphene and molybdenum disulfide are often subject to out-of-plane deformation, but its influence on electronic and nanomechanical properties remains poorly understood. These physical distortions modulate important properties which can be studied by atomic force microscopy and Raman spectroscopic mapping. Herein, we have identified and investigated different geometries of line defects in graphene and molybdenum disulfide such as standing collapsed wrinkles, fol...
#1Jian Wang(Huada: Beijing University of Chemical Technology)H-Index: 10
#2Feiyan Song(BIT: Beijing Institute of Technology)H-Index: 1
Last. Mingwang Shao(BIT: Beijing Institute of Technology)H-Index: 1
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Abstract Lightweight, easy recyclability and improved bonding can be achieved by self-reinforced polymer composites (SPC). However, the mechanical properties of SPC are usually limited. This paper describes the incorporation of graphene platelets (GNP) into polypropylene (PP) to produce PP/GNP SPC. PP/GNP fibers were firstly prepared by melt compounding and spinning, and then PP/GNP SPC were produced by film stacking. The thermal, mechanical, and morphological properties of the produced samples ...
Last. Sinan Keten(NU: Northwestern University)H-Index: 34
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Abstract Graphene oxide (GO) is a promising building block for nanocomposites due to its excellent mechanical properties and tunable interfacial interactions with polymers. While experiments have shown that GO sheets consist of graphitic regions clustering into patches and oxidized regions constituting the remaining areas, the role that these heterogeneous patches play on interfacial and mechanical properties of GO reinforced nanocomposites have not yet been investigated. To address this issue a...
The performance of graphene/epoxy nanocomposites strongly depends on the interfacial interaction between the graphene and polymer as well as the structural defects of materials. This paper investigates the effect of hydrogen functionalized graphene on tensile properties of polymer nanocomposites by using molecular dynamics simulations. The pristine graphene sheet is functionalized by adding hydrogen atoms on its edge or surface. Results show that compared with those reinforced by pristine graphe...
#1Guorui Wang(USTC: University of Science and Technology of China)H-Index: 17
#2Zhaohe Dai(University of Texas at Austin)H-Index: 22
Last. Zhong Zhang(USTC: University of Science and Technology of China)H-Index: 62
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: Out-of-plane deformation patterns, such as buckling, wrinkling, scrolling, and folding, formed by multilayer van der Waals materials have recently seen a surge of interest. One crucial parameter governing these deformations is bending rigidity, on which significant controversy still exists despite extensive research for more than a decade. Here, we report direct measurements of bending rigidity of multilayer graphene, molybdenum disulfide (MoS_{2}), and hexagonal boron nitride (hBN) based on p...
Abstract Since the first discovery of graphene in 2004, the scientific and industrial community is still finding fields to bring the excellent mechanical performance of graphene into full play. Herein, this review summarizes the recent advances in graphene and graphene derivatives toughened polymer nanocomposites, which gives full play to the unique two-dimensional nanostructure, extra specific surface area and ultrahigh mechanical properties of graphene and graphene derivatives. Using graphene ...
Understanding and designing nanoscale interfaces are essential to advancing the thermomechanical performance of polymer nanocomposites reinforced by nanocellulose. In this context, it remains to be understood how disorder introduced on the surfaces of crystals as filler materials during extraction and processing influences interfacial adhesion with glassy polymers. Using atomistic molecular dynamics (MD) simulations, here we systematically explore the interfacial adhesion between nanocellulose a...
Abstract null null The cobalt-based absorbing materials with core-shell structure have been widely investigated and developed in the microwave absorption territory, but their shortcomings such as relatively high density and weak dielectric loss limit their practical applications. In this work, taking the modification of microstructure and coating material as the cut-in point, we fabricated the Co@void@polypyrrole (PPy) nanocomposites (NCs) with yolk-shell structure and conductive polymer PPy coa...
Abstract null null In this study, polymer nanocomposites based on polyimide (PI) and nanodiamond (ND) were prepared by in-situ polymerization. Polyamic acid (PAA), a precursor of PI, was polymerized in the presence of ND. ND was highly dispersed in PI at nanoscale. The excellent mechanical and thermal properties were achieved at very low content of ND. The Young's modulus increased approximately by 70% at ND content of 0.1 wt%. The strong enhancements in the thermal decomposition temperature (fr...