Modification of mechanical properties of vertical graphene sheets via fluorination

RSC Advances ◽  
2016 ◽  
Vol 6 (14) ◽  
pp. 11161-11166 ◽  
Author(s):  
Keivan Davami ◽  
Yijie Jiang ◽  
Chen Lin ◽  
John Cortes ◽  
Jeremy T. Robinson ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Graphene Sheets ◽  
Reduced Modulus

Fluorination can significantly enhance the reduced modulus of surfaces comprised of vertical graphene sheets.

Ultrastrong, Free-Standing and Large Nanofilms of Pyrenearamid

2019 ◽  
Author(s):  
Amalia Rapakousiou ◽  
Alejandro López-moreno ◽  
Belén Nieto-Ortega ◽  
M. Mar Bernal ◽  
Miguel A. Monclús ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Building Block ◽  
Aromatic Polyamide ◽  
Free Standing ◽  
Spatial Confinement ◽  
Polymeric Structure ◽  
Reduced Modulus ◽  
Organizational Arrangement ◽  
Polycyclic Aromatic ◽  
Nanoscale Building Block

We introduce poly(1,6-pyrene terephthalamide) polymer (PPyrTA) as an aromatic polyamide analogue of poly(p-phenylene terephthalamide) (PPTA), also known as Kevlar®. This work shows that the incorporation of polycyclic aromatic pyrene moieties improves drastically the mechanical properties of the polymeric structure, increasing elastic nanoindentation-determined modulus and hardness by factors of 1.9 and 4.3, respectively. Liquid deprotonated dispersions of PPyrTA nanofibers were used as nanoscale building block for producing large-surface, free-standing polymer macroscopic nanofilms. This 2D assembly leads to further significant improvements in reduced modulus and hardness (more than twice) compared to the starting polymer macroscale fibres, due to a better re-organizational arrangement of the PPyrTA nanofibers in the nanofilms, formed under 2D spatial confinement.

Enhanced thermal and mechanical properties of epoxy composites by mixing noncovalently functionalized graphene sheets

2014 ◽  
Vol 72 (3) ◽  
pp. 453-472 ◽  
Author(s):  
Cen Zeng ◽  
Shaorong Lu ◽  
Xiane Xiao ◽  
Jian Gao ◽  
Lulu Pan ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Epoxy Composites ◽  
Graphene Sheets ◽  
Functionalized Graphene ◽  
Thermal And Mechanical Properties

Hierarchical Design and Nanomechanics of the Calcified Byssus of Anomia simplex

2009 ◽  
Vol 1187 ◽  
Author(s):  
Jakob R Eltzholtz ◽  
Marie Krogsgaard ◽  
Henrik Birkedal
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Scanning Electron Microscopy ◽  
Mechanical Performance ◽  
Blue Mussel ◽  
Hierarchical Design ◽  
Reduced Modulus ◽  
Different Types ◽  
Microscopy Images ◽  
Scanning Electron

AbstractBiology has evolved several strategies for attachment of sedentary animals. In the bivalves, byssi abound and the best known example being the protein-based byssus of the blue mussel and other Mytilidae. In contrast the bivalve Anomia sp. has a single calcified thread. The byssus is hierarchical in design and contains several different types of structures as revealed by scanning electron microscopy images. The mechanical properties of the byssus are probed by nanoindentation. It is found that the mineralized part of the byssus is very stiff with a reduced modulus of about 67 GPa and a hardness of ˜3.7 GPa. This corresponds to a modulus roughly 20% smaller than that of pure calcite and a hardness that is about 20% larger than pure calcite. The results reveal the importance of microstructure on mechanical performance.

scholarly journals Mechanical Properties and Deformation Mechanisms of Graphene Foams with Bi-Modal Sheet Thickness by Coarse-Grained Molecular Dynamics Simulations

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5622
Author(s):  
Shenggui Liu ◽  
Mindong Lyu ◽  
Chao Wang
Keyword(s):  
Mechanical Properties ◽  
Elastic Recovery ◽  
Structural Connectivity ◽  
High Stress ◽  
Sheet Thickness ◽  
Functional Materials ◽  
Deformation Mechanisms ◽  
Coarse Grained ◽  
Graphene Sheets ◽  
Graphene Foams

Graphene foams (GrFs) have been widely used as structural and/or functional materials in many practical applications. They are always assembled by thin and thick graphene sheets with multiple thicknesses; however, the effect of this basic structural feature has been poorly understood by existing theoretical models. Here, we propose a coarse-grained bi-modal GrF model composed of a mixture of 1-layer flexible and 8-layer stiff sheets to study the mechanical properties and deformation mechanisms based on the mesoscopic model of graphene sheets (Model. Simul. Mater. Sci. Eng. 2011, 19, 54003). It is found that the modulus increases almost linearly with an increased proportion of 8-layer sheets, which is well explained by the mixture rule; the strength decreases first and reaches the minimum value at a critical proportion of stiff sheets ~30%, which is well explained by the analysis of structural connectivity and deformation energy of bi-modal GrFs. Furthermore, high-stress regions are mainly dispersed in thick sheets, while large-strain areas mainly locate in thin ones. Both of them have a highly uneven distribution in GrFs due to the intrinsic heterogeneity in both structures and the mechanical properties of sheets. Moreover, the elastic recovery ability of GrFs can be enhanced by adding more thick sheets. These results should be helpful for us to understand and further guide the design of advanced GrF-based materials.

Preparation and Characterization of In Situ Nanocomposites of Graphene Nanosheets/Polyurethane

2019 ◽  
Vol 814 ◽  
pp. 90-95 ◽  
Author(s):  
Guang Lei Lv ◽  
Yuan Yuan Li ◽  
Chen Fei ◽  
Zhi Hao Shan ◽  
Jing Gan ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Tensile Strength ◽  
Graphene Nanosheets ◽  
Graphene Sheets ◽  
Microstructural Properties ◽  
Wear Performance ◽  
Polyurethane Composites

Graphene nanosheets/polyurethane (GNS/PU) was prepared in situ by polymerization technique for the manufacture of PU safety shoes soles. The graphene nanosheets/polyurethane composites were characterized for their mechanical properties, thermal conductivity and abrasion resistance, and comparison is made with those of the neat polyurethane. The microstructural properties of GNS/PU were characterized by SEM. The results show that with the increase of the amount of graphene within the range of weight-percentages analyzed, the tensile strength of the composites gradually increases. The tensile strength of the GNS/PU composites increased to 64.14 MPa with 2 wt% GNS, compared with 55.1 MPa for neat PU. When the graphene sheets reached 2 wt%, the abrasion volume reached 71 mm3. Compared with the pure PU, the wear performance of GNS/PU composites was significantly improved.

Simulation of the thermomechanical behavior of graphene/PMMA nanocomposites via continuum mechanics

2019 ◽  
Vol 11 (5) ◽  
pp. 655-669
Author(s):  
Androniki Tsiamaki ◽  
Nicolaos Anifantis
Keyword(s):  
Mechanical Properties ◽  
Accurate Method ◽  
Thermomechanical Properties ◽  
Van Der Waals Interactions ◽  
Monolayer Graphene ◽  
Graphene Sheets ◽  
Temperature Dependent ◽  
Content Type ◽  
Graphene Layers ◽  
Derived Properties

Purpose The purpose of this paper is to simulate and investigate the thermomechanical properties of graphene-reinforced nanocomposites. Design/methodology/approach The analysis proposed consists of two stages. In the first stage, the temperature-dependent mechanical properties of graphene are estimated while in the second stage, using the previously derived properties, the temperature-dependent properties of graphene-reinforced PMMA nanocomposites are investigated. In the first stage of the analysis, graphene is modeled discretely using molecular mechanics theory where the interatomic interactions are simulated by spring elements of temperature-dependent stiffness. The graphene sheets are composed of either one or more (up to five) monolayer graphene sheets connected via van der Waals interactions. However, in the second analysis stage, graphene is modeled equivalently as continuum medium and is positioned between two layers of PMMA. Also, the interphase between two materials is modeled as a medium with mechanical properties defined and bounded by the two materials. Findings The mechanical properties including Young’s modulus, shear modulus and Poisson’s ratio due to temperature changes are estimated. The numerical results show that the temperature rise and the multiplicity of graphene layers considered lead to a decrease of the mechanical properties. Originality/value The present analysis proposes an easy and accurate method for the estimation of the temperature-dependent mechanical properties of graphene-reinforced nanocomposites.

Profiling of the Mechanical Properties of Ultralow-k Films Using Nanoindentation Techniques

2011 ◽  
Vol 1297 ◽  
Author(s):  
Holm Geisler ◽  
Ulrich Mayer ◽  
Matthias U. Lehr ◽  
Petra Hofmann ◽  
Hans-Juergen Engelmann
Keyword(s):  
Mechanical Properties ◽  
Cross Sections ◽  
Light Absorption ◽  
Uv Light ◽  
Lower Surface ◽  
Rear Side ◽  
Plastic Properties ◽  
Dynamic Mechanical ◽  
Reduced Modulus ◽  
Good Agreement

ABSTRACTSeveral nanoindentation techniques were applied to the surface, the reverse side and cross-sections of PECVD ultralow-k (ULK) film stacks to characterize their elasto-plastic properties quantitatively. Results showed good agreement of the reduced modulus (Er) values measured from above and on cross-sections, respectively. Er decreased by 10-22% from the upper to the lower surface of the films. This gradient suggests that UV light absorption inside the film leads to slightly reduced curing at the rear side of the films compared to the surface of the ULK layers. Both quasi-static nanoindentation and dynamic mechanical mapping showed this trend. It is demonstrated that quantitative mechanical mapping can be performed with a lateral resolution ≤ 100nm. Slight local variations of Er were detected on ULK/SiCxNy films stacked on top of Cu-low-k interconnect structures.

Mechanical properties of bilayer graphene sheets coupled by sp3 bonding

Carbon ◽  
2011 ◽  
Vol 49 (13) ◽  
pp. 4511-4517 ◽  
Author(s):  
Y.Y. Zhang ◽  
C.M. Wang ◽  
Y. Cheng ◽  
Y. Xiang
Keyword(s):  
Mechanical Properties ◽  
Bilayer Graphene ◽  
Graphene Sheets

Mechanical Properties of Interface of Heterogeneous Diffusion Welds of Titanium and Austenitic Steel

2013 ◽  
Vol 586 ◽  
pp. 178-181 ◽  
Author(s):  
Ladislav Kolařík ◽  
Marie Kolaříková ◽  
Petr Vondrouš
Keyword(s):  
Mechanical Properties ◽  
Titanium Alloy ◽  
Austenitic Steel ◽  
Explosion Welding ◽  
Fusion Welding ◽  
Diffusion Welding ◽  
Indentation Hardness ◽  
Reduced Modulus ◽  
Titanium Alloy Ti6al4v ◽  
Stainless Austenitic Steel

Titanium is material which is used in many areas of human activity. Therefore it is necessary to join it with other material. It is very difficult to welding Ti with other metals by conventional fusion welding methods. There exist special joining technologies of heterogeneous materials which is possible to use. This is usually a joining of materials in the solid state, as diffusion welding, friction welding or explosion welding. This contribution deals with diffusion welding of titanium alloy Ti6Al4V and stainless austenitic steel 1.4301. There are described mechanical properties (as is reduced modulus Er and indentation hardness HIT) and changes of chemical composition of join due to diffusion of elements.

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