Modeling of Vertically Aligned Carbon Nanotube Composites for Vibration Damping

2009 ◽  
Author(s):  
J. Y. Jia ◽  
W. H. Liao
Keyword(s):  
Load Transfer ◽  
Epoxy Composite ◽  
Maxwell Model ◽  
Stick Slip ◽  
Slip Mechanism ◽  
Nanotube Composites ◽  
Multi Walled Carbon Nanotubes ◽  
Transfer Behavior ◽  
Vertically Aligned ◽  
Walled Carbon Nanotubes

High density aligned multi-walled carbon nanotubes (CNTs) and the CNT/epoxy composite are fabricated. To predict the energy dissipation in composites with vertically aligned multi-walled CNTs, a structural damping model of composite unit cell composed of resin, sheath and nanotube is developed. In this paper, the resin is described as viscoelastic material using Maxwell model. The CNT/epoxy composite is modeled based on the “stick-slip” mechanism, to describe the load transfer behavior between the CNT and its sheath. In order to further study the damping mechanism of the CNT composite, key parameters, such as length, center-to-center distance and critical stress of CNTs that are expected to affect the composite damping performances are studied. The simulation results show that loss factor of the CNT composite with varying parameters is sensitive to the applied stress.

scholarly journals Understanding Covalent Grafting of Nanotubes onto Polymer Nanocomposites: Molecular Dynamics Simulation Study

Sensors ◽  
2021 ◽  
Vol 21 (8) ◽  
pp. 2621
Author(s):  
Seunghwa Yang
Keyword(s):  
Molecular Dynamics ◽  
Load Transfer ◽  
Cell Model ◽  
Md Simulations ◽  
Dynamics Simulation ◽  
Covalent Grafting ◽  
Modelling Strategies ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes ◽  
External Loads

Here, we systematically interrogate the effects of grafting single-walled (SWNT) and multi-walled carbon nanotubes (MWNT) to polymer matrices by using molecular dynamics (MD) simulations. We specifically investigate key material properties that include interfacial load transfer, alteration of nanotube properties, and dispersion of nanotubes in the polymer matrix. Simulations are conducted on a periodic unit cell model of the nanocomposite with a straight carbon nanotube and an amorphous polyethylene terephthalate (PET) matrix. For each type of nanotube, either 0%, 1.55%, or 3.1% of the carbon atoms in the outermost nanotubes are covalently grafted onto the carbon atoms of the PET matrix. Stress-strain curves and the elastic moduli of nanotubes and nanocomposites are determined based on the density of covalent grafting. Covalent grafting promotes two rivalling effects with respect to altering nanotube properties, and improvements in interfacial load transfer in the nanocomposites are clearly observed. The enhanced interface enables external loads applied to the nanocomposites to be efficiently transferred to the grafted nanotubes. Covalent functionalization of the nanotube surface with PET molecules can alter the solubility of nanotubes and improve dispersibility. Finally, we discuss the current limitations and challenges in using molecular modelling strategies to accurately predict properties on the nanotube and polymers systems studied here.

Interface Engineering of CNT/Polymer Nanocomposites With Tunable Damping Properties

2018 ◽  
Author(s):  
Michela Talò ◽  
Giulia Lanzara ◽  
Maryam Karimzadeh ◽  
Walter Lacarbonara
Keyword(s):  
Load Transfer ◽  
Mechanical Response ◽  
Material Design ◽  
Tensile Tests ◽  
Nanocomposite Films ◽  
Damping Capacity ◽  
Interfacial Region ◽  
Material Damping ◽  
Stick Slip ◽  
Multi Walled Carbon Nanotubes

In this work, the arising of stick-slip dissipation as well as the global mechanical response of carbon nanotube (CNT) nanocomposite films are tailored by exploiting a three-phase nanocomposite. The three phases are represented by the CNTs, a polymer coating localized on the CNTs surface and a hosting matrix. In particular, a polystyrene (PS) layer coats multi-walled carbon nanotubes (MWNTs) that are randomly dispersed in a polyimide (PI) matrix. The coating phase is strongly bonded to the CNTs outer sidewalls ensuring the effectiveness of the load transfer mechanism and reducing the material damping capacity. The coating phase can be thermally-activated to modify, and in particular, decrease the CNT-matrix interfacial shear strength (ISS) thus facilitating the stick-slip onset in the nanocomposite. The ISS decrease finds its roots in a partial degradation of the coating phase and, in particular, in the formation of voids. By weakening the CNT/polymer interfacial region, a significant enhancement in the material damping capacity is observed. An extensive experimental campaign consisting of monotonic and cyclic tensile tests proved the effectiveness of this novel multi-phase material design.

scholarly journals PRELIMINARY STUDY OF ELECTROPHORETIC DEPOSITION OF VERTICALLY ALIGNED MWCNT ON METALLIC ELECTRODE

2012 ◽  
Vol 05 ◽  
pp. 704-711
Author(s):  
SIAVASH KHABAZIAN ◽  
SOHRAB SANJABI
Keyword(s):  
Carbon Nanotubes ◽  
Metallic Electrode ◽  
Aqueous Solvent ◽  
Multi Walled Carbon Nanotubes ◽  
Dc Electric Field ◽  
Ft Ir ◽  
Vertically Aligned ◽  
Preliminary Study ◽  
Walled Carbon Nanotubes ◽  
Scanning Electron

Multi-walled carbon nanotubes films formed randomly aligned laterally by electrophoresis. Multi-walled carbon nanotubes with lengths of about 10 μ was shortened and functionalized by a mixture of sulfuric and nitric acid. The functional groups on carbon nanotubes were elaborated by FT-IR. Chemically shortened MWCNTs disperse in organic and aqueous solvent and deposited on electrode vertically-aligned by applying a constant DC electric field. The alignment of MWCNTs was observed by scanning electron microscopy. It also the effect of various substrates on alignment of multi-walled carbon nanotubes was investigated.

scholarly journals Conjugated polyelectrolyte nano field emission adlayers

2016 ◽  
Vol 1 (4) ◽  
pp. 304-312 ◽  
Author(s):  
M. T. Cole ◽  
R. J. Parmee ◽  
A. Kumar ◽  
C. M. Collins ◽  
M. H. Kang ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Field Emission ◽  
Electron Emission ◽  
Field Electron Emission ◽  
Conjugated Polyelectrolyte ◽  
Emission Performance ◽  
Field Electron ◽  
Multi Walled Carbon Nanotubes ◽  
Vertically Aligned ◽  
Walled Carbon Nanotubes

Here we report on a straightforward and rapid means of enhancing the field electron emission performance of nascent vertically aligned multi-walled carbon nanotubes by introducing a polar zwitterionic conjugated polyelectrolyte adlayer at the vacuum–emitter interface.

Effect of Ferrocene Catalyst and Hydrogen Feed on Microstructures of Vertically Aligned MWCNTs

2016 ◽  
Vol 701 ◽  
pp. 8-12
Author(s):  
Shazia Shukrullah ◽  
Norani Muti Mohamed ◽  
Maizatul Shima Shaharun ◽  
Muhammad Yasar
Keyword(s):  
Carbon Nanotubes ◽  
Vapour Deposition ◽  
Chemical Vapour ◽  
Areal Density ◽  
Optimum Conditions ◽  
Catalyst Amount ◽  
Multi Walled Carbon Nanotubes ◽  
Cvd Growth ◽  
Vertically Aligned ◽  
Walled Carbon Nanotubes

This study investigated the effect of catalyst amount on chemical vapour deposition (CVD) growth of multi-walled carbon nanotubes (MWCNTs) with and without hydrogen feed. The ferrocene weight was varied from 100 mg to 200 mg for CNTs growth over Si/SiO2/Al2O3 substrate. Very few CNTs were seen in micrographs of the samples produced in the absence of the hydrogen feed. Most of the carbon atoms precipitated into amorphous carbon due to existence of inactive catalyst particles. However, CNT structures grown with hydrogen feed were more distinct; the nanotubes were thinner, straight and highly crystalline. MWCNTs arrays/forest length was also increased from 120 µm to 850 µm with hydrogen feed. An increase in catalyst weight significantly affected the diameter, crystallinity, alignment and growth of nanotubes. The lowest inner-shell spacing of 0.348 nm was obtained with 150 mg of ferrocene, which is an indication of growth of relatively pure CNTs. Under the optimum conditions, the areal density of the ferrocene particles was sufficiently increased to get required alignment and crystallinity of MWCNTs.

Comparing Field Emission Stability of Lithography-free, Modified Multi-walled Carbon Nanotubes

2009 ◽  
Vol 1204 ◽  
Author(s):  
Archana Pandey ◽  
Abhishek Prasad ◽  
Jason Moscatello ◽  
Yoke Khin Yap
Keyword(s):  
Carbon Nanotubes ◽  
Dielectric Constant ◽  
Methyl Methacrylate ◽  
Field Emission ◽  
Field Emission Properties ◽  
Emission Stability ◽  
Multi Walled Carbon Nanotubes ◽  
Vertically Aligned ◽  
Walled Carbon Nanotubes ◽  
Stable Field

AbstractField emission from carbon nanotubes (CNTs) has been known for more than a decade but there is no commercialized product available in the market. Apparently, we need to improve our basics understanding on stable field emission from CNTs. Here we compared the field emission properties of as grown vertically-aligned multi-walled carbon nanotubes (MWCNTs) to two types of modified MWCNTs: 1) Conical bundles of opened-tip MWCNTs, and 2) Opened-tip MWCNTs embedded in poly-methyl methacrylate (PMMA). We found that both types of modified MWCNTs have lower emission thresholds and better emission stability than the as grown samples. Among these modified samples, MCNTs embedded in PMMA has lower emission thresholds and better emission stability. We attributed these improvements to the filling of spacing between MWCNTs with PMMA that has higher dielectric constant than vacuum.

scholarly journals Mechanical, Electrical and Rheological Behavior of Ethylene-Vinyl Acetate/Multi-Walled Carbon Nanotube Composites

Polymers ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1300 ◽  
Author(s):  
Stanciu ◽  
Stan ◽  
Sandu ◽  
Susac ◽  
Fetecau ◽  
...  
Keyword(s):  
Vinyl Acetate ◽  
Mechanical Response ◽  
Ethylene Vinyl Acetate ◽  
Flow Index ◽  
Melt Temperature ◽  
High Shear Rates ◽  
Nanotube Composites ◽  
Multi Walled Carbon Nanotubes ◽  
Rheological Experiments ◽  
Walled Carbon Nanotubes

This paper investigates the rheological, mechanical and electrical properties of a Ethylene-Vinyl Acetate (EVA) polymer filled with 1, 3 and 5 wt.% multi-walled carbon nanotubes (MWCNTs). The melt flow and pressure-volume-Temperature (pvT) behaviors of the EVA/MWCNT composites were investigated using a high-pressure capillary rheometer, while the electro-mechanical response was investigated on injection-molded samples. Rheological experiments showed that the melt shear viscosity of the EVA/MWCNT composite is dependent on nanotube loading and, at high shear rates, the viscosity showed temperature-dependent shear thinning behavior with a flow index n < 0.35. The specific volume of the EVA/MWCNT composite decreased with increasing pressure and MWCNT wt.%. The transition temperature, corresponding to the pvT crystallization, increased linearly with increasing pressure, i.e., about 20 to 30 °C when cooling under pressure. The elastic modulus, tensile strength and stress at break increased with increasing MWCNT wt.%, whereas the strain at break decreased, suggesting the formation of MWCNT secondary agglomerates. The electrical conductivity of the EVA/MWCNT composite increased with increasing MWCNT wt.% and melt temperature, reaching ~10−2 S/m for the composite containing 5 wt.% MWCNTs. Using the statistical percolation theory, the percolation threshold was estimated at 0.9 wt.% and the critical exponent at 4.95.

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