“…The maximum stress is around 1.3 GPa, and the effective tensile modulus approximates 16 GPa (based on the least square fitting with e < 5%). Such results are consistent with that reported previously for cup-stacked NF [50]. According to the atomic configurations ( Figure 2c), both NF-S and NF deform like a continuum fiber in this stage with no detectable structural changes, which is governed by the interlayer vdW interactions.…”
Section: Super-elastic Tensile Behaviorsupporting
confidence: 92%
“…Since the adjacent layers are adhered to each through the van der Waals (vdW) interactions, the NFs exhibit a small yielding strain around 7% [50]. Our recent works show that a helicoid nanostructure constructed from a screw dislocation of 2D nanomaterials possesses a super-elastic tensile characteristic [51,52].…”
Section: Introductionmentioning
confidence: 99%
“…Comparing with the mono-layer carbon nanocones, few studies have investigated the mechanical properties of the NFs with stacked carbon nanocones. A recent study show that the tensile properties of the cup-stacked NFs can be significantly changed through thermal treatments, which introduces surface bonds between adjacent layers [50].…”
Carbon nanofibers (NFs) have been envisioned with broad promising applications, such as nanoscale actuators and energy storage medium. This work reports for the first-time superelastic tensile characteristics of NFs constructed from a screw dislocation of carbon nanocones (NF-S). The NF-S exhibits three distinct elastic deformation stages under tensile, including an initial homogeneous deformation, delamination, and further stretch of covalent bonds. The delamination process endows the NF-S extraordinary tensile deformation capability, which is not accessible from its counterpart with a normal cup-stacked geometry. The failure of NF-S is governed by the inner edges of the nanocone due to the strain concentration, leading to a common failure force for NF-S with varying geometrical parameters. Strikingly, the delamination process is dominated by the inner radius and the apex angle of the nanocone. For a fixed apex angle, the yielding strain increases remarkably when the inner radius increases, which can exceed 1000%. It is also found that the screw dislocation allows the nanocones flattening and sliding during compression. This study provides a comprehensive understanding on the mechanical properties of NFs as constructed from carbon nanocones, which opens new avenues for novel applications, such as nanoscale actuators. (Haifei Zhan) 1 = ( /2) and 1 = ( /2), respectively. Considering the close packing morphology, i.e., the distance between each layer equals to the graphite distance (b = 3.35 Å), the effective height or length of the nanofiber can be approximated as ℎ 1 = ( − 1) /sin ( 2 ⁄ ). Thus, the cross-section and volume of the nanofiber can be approximated as 1 = ( = − = ) sin( 2 ⁄ ) = , and 1 = ( − 1)( = − = )sin ( 2 ⁄ ).
“…The maximum stress is around 1.3 GPa, and the effective tensile modulus approximates 16 GPa (based on the least square fitting with e < 5%). Such results are consistent with that reported previously for cup-stacked NF [50]. According to the atomic configurations ( Figure 2c), both NF-S and NF deform like a continuum fiber in this stage with no detectable structural changes, which is governed by the interlayer vdW interactions.…”
Section: Super-elastic Tensile Behaviorsupporting
confidence: 92%
“…Since the adjacent layers are adhered to each through the van der Waals (vdW) interactions, the NFs exhibit a small yielding strain around 7% [50]. Our recent works show that a helicoid nanostructure constructed from a screw dislocation of 2D nanomaterials possesses a super-elastic tensile characteristic [51,52].…”
Section: Introductionmentioning
confidence: 99%
“…Comparing with the mono-layer carbon nanocones, few studies have investigated the mechanical properties of the NFs with stacked carbon nanocones. A recent study show that the tensile properties of the cup-stacked NFs can be significantly changed through thermal treatments, which introduces surface bonds between adjacent layers [50].…”
Carbon nanofibers (NFs) have been envisioned with broad promising applications, such as nanoscale actuators and energy storage medium. This work reports for the first-time superelastic tensile characteristics of NFs constructed from a screw dislocation of carbon nanocones (NF-S). The NF-S exhibits three distinct elastic deformation stages under tensile, including an initial homogeneous deformation, delamination, and further stretch of covalent bonds. The delamination process endows the NF-S extraordinary tensile deformation capability, which is not accessible from its counterpart with a normal cup-stacked geometry. The failure of NF-S is governed by the inner edges of the nanocone due to the strain concentration, leading to a common failure force for NF-S with varying geometrical parameters. Strikingly, the delamination process is dominated by the inner radius and the apex angle of the nanocone. For a fixed apex angle, the yielding strain increases remarkably when the inner radius increases, which can exceed 1000%. It is also found that the screw dislocation allows the nanocones flattening and sliding during compression. This study provides a comprehensive understanding on the mechanical properties of NFs as constructed from carbon nanocones, which opens new avenues for novel applications, such as nanoscale actuators. (Haifei Zhan) 1 = ( /2) and 1 = ( /2), respectively. Considering the close packing morphology, i.e., the distance between each layer equals to the graphite distance (b = 3.35 Å), the effective height or length of the nanofiber can be approximated as ℎ 1 = ( − 1) /sin ( 2 ⁄ ). Thus, the cross-section and volume of the nanofiber can be approximated as 1 = ( = − = ) sin( 2 ⁄ ) = , and 1 = ( − 1)( = − = )sin ( 2 ⁄ ).
“…For pure cellulose aerogels, stress is condensed in the curved region, resulting in rapid propagation of cracks across the cellulose aerogels, leading to the breakage of the cellulose aerogels. Otherwise, for the cellulose aerogels with AH NPs uniformly distributed in the cellulose matrix, the concentrated stress could be effectively scattered and dissipated. , Moreover, the uniformly distributed AH NPs with an appropriate size in the cellulose matrix were believed to act as buffer substances to inhibit or change the extension direction of tiny cracks. Meanwhile, the energy originated from the external stress was absorbed; therefore, the structural fracture of the cellulose matrix could be effectively avoided.…”
The production of cellulose-based aerogels from the conversion of cheap and rich precursors using environmentally friendly techniques is a very attractive subject in materials chemistry. In this work, we reports a facile strategy to construct flame retardant, sound-adsorption and mechanical enhancement cellulose-based composite aerogels by the incorporation of aluminum hydroxide nanoparticles (AH NPs) into cellulose gels via an in-situ sol-gel process, followed by freeze-drying to coat AH NPs on cellulose composite aerogels (AH NPs@cellulose composite aerogels). The results demonstrated that the AH NPs homogeneous dispersion within cellulose aerogel, and the presence of AH NPs did not have a remarkable influence on the homogeneous porous structure of cellulose aerogels when compared with cellulose aerogel prepared from the NaOH/urea/thiourea solution. The prepared composite cellulose aerogels showed excellent flame retardancy, the peak of heat release rate (PHRR) of the composite aerogels decreased significantly from 280 W/g of the control sample to 22 W/g, and total heat release (THR) of the composite aerogels decreased remarkably from 13.2 kJ/g to 1.6 kJ/g. Moreover, the incorporation of AH NPs composite aerogels exhibited remarkable mechanical properties, the compressive strength of the composite aerogels increased significantly from 0.08 MPa to 1.5 MPa. In addition, AH NPs composite cellulose aerogels have excellent sound absorption at high frequencies with a maximum sound absorption coefficient of 1. AH NPs composite cellulose aerogels have strong water and oil affinity. After immersing the samples in mixed silica nanoparticles, heptadecafluorononanoic, and fluoroalkyl silane solutions they became super-antiwetting, with a water contact angle (CA) larger than 150° and oil CA larger than 140°. In summary, this study provides a facile strategy to rationally construct flame retardant, mechanically robust, high-efficiency sound-adsorption and superamphiphobic cellulose-based composite aerogels, which have promising applications in the future as green engineering materials.
“…(Movie S1 ) also presents the good flexibility of CA4-800 composite sample. Carbon nanofibers are significantly structural and useful materials owing to its excellent mechanical and electrical properties and thus widely used as reinforcements for better nanocomposites with enhanced performance 21 , 22 . Figure 2 FE-SEM images of ( a ) CNFs-800, ( b ) CA2-800, ( c ) CA3-800, ( d ) CA4-800 and the digital images presenting the flexibility of ( e ) CA3-800 and ( f ) CA4-800 samples.…”
Electromagnetic (EM) wave absorbing materials have been fabricated from diverse materials such as conductive polymers, carbon based nanostructures and magnetic metal oxides. Nevertheless, it has remained a great challenge to develop lightweight and high-efficiency EM wave absorbing materials with a broad frequency range. Herein, we report a scalable strategy to create Co3O4/carbon composite nanofibrous membrane by electrospinning technique followed by stabilization and carbonization processes. An optimal reflection loss (RL) value of 36.27 dB is reached at 13.76 GHz for a layer of 2 mm thickness. RL exceeding −20 dB can be realized in any interval within the 4.5–14.4 GHz range by selecting a proper thickness of the absorbing layer between 1 and 5 mm. The Co3O4/carbon composite nanofibrous membrane could be well served as promising and attractive candidates for lightweight and enhanced EM wave absorbing materials. This presented research provides an innovative and effective approach to design the novel EM wave absorbing material in a broad frequency range for practical applications.
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