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Understanding Mechanical Response of Elastomeric Graphene Networks.

Ni N, Barg S, Garcia-Tunon E, Macul Perez F, Miranda M, Lu C, Mattevi C, Saiz E - Sci Rep (2015)

Bottom Line: In this work, we constructed elastomeric graphene porous networks with well-defined structures by freeze casting and thermal reduction, and investigated systematically the effect of key microstructural features.A better restoration of the graphitic nature also has a considerable effect.These findings suggest that an improvement in the mechanical properties of porous graphene networks significantly depend on the engineering of the graphene flake that controls the property of the cell walls.

View Article: PubMed Central - PubMed

Affiliation: Centre for Advanced Structural Ceramics, Department of Materials, Imperial College London, London SW7 2AZ, UK.

ABSTRACT
Ultra-light porous networks based on nano-carbon materials (such as graphene or carbon nanotubes) have attracted increasing interest owing to their applications in wide fields from bioengineering to electrochemical devices. However, it is often difficult to translate the properties of nanomaterials to bulk three-dimensional networks with a control of their mechanical properties. In this work, we constructed elastomeric graphene porous networks with well-defined structures by freeze casting and thermal reduction, and investigated systematically the effect of key microstructural features. The porous networks made of large reduced graphene oxide flakes (>20 μm) are superelastic and exhibit high energy absorption, showing much enhanced mechanical properties than those with small flakes (<2 μm). A better restoration of the graphitic nature also has a considerable effect. In comparison, microstructural differences, such as the foam architecture or the cell size have smaller or negligible effect on the mechanical response. The recoverability and energy adsorption depend on density with the latter exhibiting a minimum due to the interplay between wall fracture and friction during deformation. These findings suggest that an improvement in the mechanical properties of porous graphene networks significantly depend on the engineering of the graphene flake that controls the property of the cell walls.

No MeSH data available.


Related in: MedlinePlus

In situ high-resolution SEM images showing the microstructural change at different strain levels during the deformation for rGO-PNs with (a) lamellar structure and (b) cellular structure. Scale bar: 20 μm. (c) Evolution of a pre-exist defect during deformation. Scale bar: 10 μm.
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f5: In situ high-resolution SEM images showing the microstructural change at different strain levels during the deformation for rGO-PNs with (a) lamellar structure and (b) cellular structure. Scale bar: 20 μm. (c) Evolution of a pre-exist defect during deformation. Scale bar: 10 μm.

Mentions: The porous networks can recover its original volume with little macroscopic permanent deformation after being subjected to high compressive strains of up to 0.8 or after compressive cycling (Fig. 4b,c). The materials retain over 82% of their maximum stress after the cyclic compression. Large recoverability (<3% permanent deformation after 50% strain) was observed for samples with densities as low as ∼2.6 mg/cm3. While a direct comparison is difficult as the measured values are influenced by the foam density and testing conditions, this superelastic behaviour appears to be comparable or superior to other porous carbon structures3172425. The microstructural changes of the porous structure during compression can be followed by in-situ SEM (Fig. 5a,b). The microstructure recovers almost completely after loading is removed even after high deformations. On the other hand, propagation of pre-existing defects such as micro-cracks (Fig. 5c) and wrinkling of the cell walls (Figure S9b and c in reference 4) are responsible for the small non-recoverable deformation and the observed decrease in mechanical properties.


Understanding Mechanical Response of Elastomeric Graphene Networks.

Ni N, Barg S, Garcia-Tunon E, Macul Perez F, Miranda M, Lu C, Mattevi C, Saiz E - Sci Rep (2015)

In situ high-resolution SEM images showing the microstructural change at different strain levels during the deformation for rGO-PNs with (a) lamellar structure and (b) cellular structure. Scale bar: 20 μm. (c) Evolution of a pre-exist defect during deformation. Scale bar: 10 μm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4562249&req=5

f5: In situ high-resolution SEM images showing the microstructural change at different strain levels during the deformation for rGO-PNs with (a) lamellar structure and (b) cellular structure. Scale bar: 20 μm. (c) Evolution of a pre-exist defect during deformation. Scale bar: 10 μm.
Mentions: The porous networks can recover its original volume with little macroscopic permanent deformation after being subjected to high compressive strains of up to 0.8 or after compressive cycling (Fig. 4b,c). The materials retain over 82% of their maximum stress after the cyclic compression. Large recoverability (<3% permanent deformation after 50% strain) was observed for samples with densities as low as ∼2.6 mg/cm3. While a direct comparison is difficult as the measured values are influenced by the foam density and testing conditions, this superelastic behaviour appears to be comparable or superior to other porous carbon structures3172425. The microstructural changes of the porous structure during compression can be followed by in-situ SEM (Fig. 5a,b). The microstructure recovers almost completely after loading is removed even after high deformations. On the other hand, propagation of pre-existing defects such as micro-cracks (Fig. 5c) and wrinkling of the cell walls (Figure S9b and c in reference 4) are responsible for the small non-recoverable deformation and the observed decrease in mechanical properties.

Bottom Line: In this work, we constructed elastomeric graphene porous networks with well-defined structures by freeze casting and thermal reduction, and investigated systematically the effect of key microstructural features.A better restoration of the graphitic nature also has a considerable effect.These findings suggest that an improvement in the mechanical properties of porous graphene networks significantly depend on the engineering of the graphene flake that controls the property of the cell walls.

View Article: PubMed Central - PubMed

Affiliation: Centre for Advanced Structural Ceramics, Department of Materials, Imperial College London, London SW7 2AZ, UK.

ABSTRACT
Ultra-light porous networks based on nano-carbon materials (such as graphene or carbon nanotubes) have attracted increasing interest owing to their applications in wide fields from bioengineering to electrochemical devices. However, it is often difficult to translate the properties of nanomaterials to bulk three-dimensional networks with a control of their mechanical properties. In this work, we constructed elastomeric graphene porous networks with well-defined structures by freeze casting and thermal reduction, and investigated systematically the effect of key microstructural features. The porous networks made of large reduced graphene oxide flakes (>20 μm) are superelastic and exhibit high energy absorption, showing much enhanced mechanical properties than those with small flakes (<2 μm). A better restoration of the graphitic nature also has a considerable effect. In comparison, microstructural differences, such as the foam architecture or the cell size have smaller or negligible effect on the mechanical response. The recoverability and energy adsorption depend on density with the latter exhibiting a minimum due to the interplay between wall fracture and friction during deformation. These findings suggest that an improvement in the mechanical properties of porous graphene networks significantly depend on the engineering of the graphene flake that controls the property of the cell walls.

No MeSH data available.


Related in: MedlinePlus