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1 |
Nanoinfiltration behavior of carbon nanotube based nanocomposites with enhanced mechanical and electrical properties
رفتار نانوفیلتراسیون نانوکامپوزیت های مبتنی بر نانولوله کربنی با خواص مکانیکی و الکتریکی بهبود یافته-2021 In this work, carbon nanotube (CNT) based nanocomposites with high mass fraction are proposed by
in-situ bridging carbon matrix into CNT paper through optimized chemical vapor infiltration (CVI).
Nanoinfiltration behavior of CNTs is basically investigated under the CVI process. The contact between
each CNT can be strengthened and the conductive pathways can be established, resulting in the better
mechanical and electrical properties. Compared with the pristine CNT paper, the CNT/C composite after
pyrolysis process confirms a remarkable advance in tensile strength (up to 310 ± 13 MPa) and Young’s
modulus (up to 2.4 ± 0.1 GPa). Besides, a notable feature of electrical conductivity also shows an improvement up to 8.5 S/cm, which can be attributed to the mass fraction of CNT (41 wt%) breaking the limits of
percolation thresholds and the efficient densification of this sample to establish the conductive pathways.
This study has a broad application in the development of the multi-functional electrical and engineering
materials.
Keywords: Carbon nanotube | Chemical vapor infiltration (CVI) | Nanocomposites |
مقاله انگلیسی |
2 |
Mechanical properties and electrical resistivity of multiwall carbon nanotubes incorporated into high calcium fly ash geopolymer
Mechanical properties and electrical resistivity of multiwall carbon nanotubes incorporated into high calcium fly ash geopolymer-2021 High calcium fly ash (HCF) is a pozzolan material and is available in large quantity in Thailand
due to the existence of coal-based electrical power plants. It is used as a supplemental material to
partially replace cement content in concrete as a movement toward concrete sustainability. In
order to lift the sustainability level, a cementitious material without Portland cement called
‘geopolymer’ was introduced. Geopolymer can be produced from raw materials containing high
alumina and silica, for example fly ash, blast furnace slag, and metakaolin. For high calcium fly
ash geopolymer (HCFG), the unique properties include fast setting, and high early strength. In this
study, in order to enhance the properties of HCF geopolymer, multiwall carbon nanotubes
(MWCNTs) were introduced into the matrix. In addition to the investigation into basic properties,
the effect of MWCNT on electrical resistivity was also investigated to determine its potential use
in piezoelectric sensor applications. The results showed that the addition of MWCNTs improved
the mechanical properties of HCFG. The maximum compressive and flexural strengths were obtained with a mix containing 0.2% MWCNTs. The EDS test also indicated the increase in geopolymerization and hydration products with the addition of MWCNTs. To investigate the
piezoelectricity potential, the electrical resistivity under different levels of compression loads was
investigated. The resistivity decreased with the increasing load level up to the first crack, and then
decreased. The changes in electrical resistivity indicated the potential use of HCFG incorporated
MWCNTs in self-sensing for structural health monitoring.
Keywords: Geopolymer | High calcium fly ash | Multiwall carbon nanotube | Electrical resistivity |
مقاله انگلیسی |
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Effect of CNT additives on the electrical properties of derived nanocomposites (experimentally and numerical investigation)
تأثیر افزودنیهای CNT بر خواص الکتریکی نانوکامپوزیتهای مشتقشده (بررسی تجربی و عددی)-2021 In this work, two simulations models have been developed to study the electrical percolation and the
electrical conductivity of epoxy-based nanocomposite containing Multi-walled Carbon Nanotubes. The
models are based on resistor-model and finite element analysis. The former was evaluated using
MATLAB code and the finite element analysis using DIGIMAT software. The maximum tunneling distance
and its influence on the percolation probability and final electrical conductivity were studied. Electrical
measurements on the samples were conducted for numerical validation. The experimental data showed a
percolation achievement around 2 wt%, which was confirmed in the numerical simulations. This study
provides evidence of the effectiveness of the resistor model and finite element method approach to predict the electrical conductivity of nanocomposites.
Keywords: Polymer-matrix composites (PMCs) | Nanocomposites | Carbon nanotube | Electrical properties | Computational modelling |
مقاله انگلیسی |
4 |
Moisture dependence of electrical resistivity in under-percolated cement-based composites with multi-walled carbon nanotubes
وابستگی مقاومت الکتریکی به رطوبت در کامپوزیت های پایه سیمانی کم نفوذ با نانولوله های کربنی چند جداره-2021 Cement-based piezoresistive composites have attracted significant attention as smart construction materials for embedding self-sensing capability in concrete infrastructure. Although a number of studies have been conducted using multi-walled carbon nanotubes (MWCNTs) as a functional filler for self-sensing cement-based composites, studies addressing the influence of the internal moisture state on the electrical properties are relatively scant. In this study, we aim to experimentally investigate the effect of internal moisture state on the electrical resistivity of cement-based composites containing MWCNTs as an electrically conductive medium to raise a need for calibration of self-sensing data considering the internal moisture state. To this end, the moisture dependence of electrical resistivity in under-percolated cement-based composites was mainly evaluated, along with other material properties such as strength, shrinkage, and flowability. Results revealed that the electrical resistivity increased almost linearly as the internal relative humidity (IRH) decreased, and the increase was more pronounced below the percolation threshold. In addition, it was found that the strength gained by the microfiller effect of MWCNTs was significantly reduced particularly in under-percolated mixtures, leading to overall strength reductions. Furthermore, this study showed that the more the MWCNT was added, the smaller the flowability was obtained due to the increased viscosity of the mixture. The findings of this study are expected to provide pivotal information for accurate and reliable interpretations of self-sensing data generated by MWCNT-embedded cement-based composites.
Keywords: carbon nanotubes | cement-based composites | electrical resistivity | internal relative humidity | percolation threshold | self-sensing |
مقاله انگلیسی |
5 |
Definition of “b” exponent and development of power-law model for electrical conductivity of polymer carbon nanotubes nanocomposites
تعریف توان "b" و توسعه مدل قدرت قانون برای هدایت الکتریکی نانوکامپوزیت های نانولوله های کربن پلیمر-2020 In this article, the conventional power-law model for electrical conductivity of polymer carbon nanotubes (CNT)
nanocomposites (PCNT) is linked with a developed model. The main goal is to define the “b” exponent and
develop the power-law model for conductivity of PCNT. The interphase region surrounding nanoparticles and
the CNT waviness, which affect the percolation threshold, the fraction of networked CNT and the effective
volume fraction of CNT are taken into account. The developed model expresses that CNT concentration, CNT
length and interphase thickness positively handle the conductivity of PCNT, while thick and waved CNT cause
the adverse effect. Moreover, the calculations of the developed model accurately follow the experimental results
of conductivity and “b” raises as CNT concentration increases. Keywords: Polymer CNT nanocomposites | Electrical conductivity | Power-law model | Interphase region | Modeling |
مقاله انگلیسی |
6 |
Construction of various nanostructures on carbon nanotube films
ساخت انواع نانوساختارها بر روی فیلم های نانولوله کربنی-2020 Construction of nanostructures on surfaces has appealed intensive attention due to its significant applications
in diverse fields. Especially, engineering surface properties via surficial nanostructures is
actually the creation of functional interface-based materials and slated to be the key aspect for the future
of materials science. Although many efforts have been made, there are only a few reports about the
construction of nanostructures on carbon nanotube film surfaces. The big challenge for constructing on
carbon films is that these carbon assemblies are easy to be dispersed by immersion in a chemical solution.
Here, in this paper, we have shown for the first time the fabrication of different kinds of nanostructures,
i.e. nanoneedles, nanoparticles, nanospirals, on carbon nanotube films by using facile and
cheap electrodeposition method and precise physical deposition method. We pretreat the films by an
electrical method to strengthen the films to avoid dispersion during the electrodeposition process. These
composite films are still very flexible after coating with nanostructures. Compared with those precise
physical deposition methods, the facile electrodeposition method is more suitable for constructing
nanostructures on carbon nanotube films, due to the low requirement for planeness of films. It is
interesting to find that these nanostructures can endow superhydrophobicity or higher conductivity for
these flexible composite films, which greatly broaden the potential applications for carbon nanotube
films in the fields of battery, moisture self-cleaning, electrostatic energy harvesting, and enhancing
condensation heat transfer for more efficiency of energy utilization, environmental, and thermal
management Keywords: Arrays of nanostructures | Nano films | Superhydrophobicity | Environmental and energy management |
مقاله انگلیسی |
7 |
Characterisation and computational analysis of a novel lipase nanobio-based reagent for visualising latent fingerprints on water-immersed glass slides
خصوصیات و تجزیه و تحلیل محاسباتی یک معرف مبتنی بر نانو بیو لیپاز برای تجسم اثر انگشت نهان در اسلایدهای شیشه غوطه ور در آب-2020 Considering the significant evidential values of fingerprints in underwater criminal investigations and the need
to visualise them using a user- and environmentally-friendly reagent, development of a novel, rapid and relatively
greener nanobio-based reagent (NBR) is deemed beneficial. Lipase from the commercial Candida rugosa
immobilised onto acid-functionalised multi-walled carbon nanotubes (NBR) was used as the safer and cheap
lipid-sensing reagent to visualise groomed whole/split fingerprints on non-porous objects immersed in stagnant
tap water for up to 30 days under a laboratory-controlled setting. Attenuated Total Reflectance – Fourier
Transform Spectrometry, Field Emission Scanning Electron Microscopy and bioinformatics (molecular docking
and molecular dynamics simulations) were employed to characterise and confirm the attachment of NBR onto
the lipid constituents of wet fingerprints. Chromatographic results further confirmed the presence of n-hexadecanoic
and octadecanoic acids on fingerprints up to 30 days of immersion. Thus, NBR may potentially be
useful as the future state-of-the-art fingerprint visualisation technology. Keywords: Latent fingerprint | Nanobio-based reagent | Candida rugosa lipase | Bioinformatics | Forensic science |
مقاله انگلیسی |
8 |
Data mining to predict the average outer diameter of vertically aligned TiO2 nanotubes
داده کاوی برای پیش بینی میانگین قطر بیرونی نانو لوله های TiO2 به صورت عمودی-2019 Nowadays, the development of new technology is strongly based on nanomaterials studies, such as vertically
aligned TiO2 nanotubes (TONTs), which are widely used in different fields of industry. Physical properties of
these materials depend on their size (inner and outer diameters) and shape, for this reason they must be measured
accurately. Inner and outer diameter measurement is performed manually on images obtained by means of
scanning electron microscopy. Time-consuming image analysis, subjective and low-representative readings are
some disadvantages found in this process. This paper proposes a model to predict the average outer diameter of
TONTs using Data Mining and Ellipsometry, because they have the potential to overcome disadvantages mentioned
above. The diameter with measurements of light reflection intensity and ellipsometric parameters is
modelled using different techniques. A model that shows a very low prediction error using linear support vector
machines for regression is reported. Keywords: Data mining | Outer diameter measurement | Vertically aligned nanotubes | Ellipsometry |
مقاله انگلیسی |
9 |
Application of the voltammetric electronic tongue based on nanocomposite modified electrodes for identifying rice wines of different geographical origins
کاربرد زبان الکترونیکی ولتامتری بر اساس الکترودهای اصلاح شده نانو کامپوزیت برای شناسایی شراب برنج با منشأ جغرافیایی مختلف-2019 In the study, the voltammetric electronic tongue based on three nanocomposites modified electrodes
was applied for the identification of rice wines of different geographical origins. The nanocomposites
were prepared by gold and copper nanoparticles in the presence of conducting polymers (polymer
sulfanilic acid, polymer glutamic acid) and carboxylic multi - walled carbon nanotubes. The modified
electrodes showed high sensitivity to guanosine - 5 - monophosphate disodium salt, tyrosine and gallic
acid which have good correlation with the geographical origins of rice wines. Scanning electron microscopy
was performed to display the surface morphologies of the nanocomposites, and cyclic voltammetry
was applied to study the electrochemical behaviors of the taste substances on the electrode
surfaces. Four types of electrochemical parameters (pH, scan rates, accumulation potentials and time)
were optimized for getting a low limit of the detection of each taste substance. The geographical information
of rice wines was obtained by the modified electrodes based on two types of multi - frequency
large amplitude pulse voltammetry, and “area method” was applied for extracting the feature data from
the original information obtained. Based on the area feature data, principal component analysis, locality
preserving projection (LPP), and linear discriminant analysis were applied for the classification of the rice
wines of different geographical origins, and LPP presented the best results; extreme learning machine
(ELM) and alibrary for support vector machines were applied for predicting the geographical origins of
rice wines, and ELM performed better. Keywords: Nanocomposites modified electrodes | Conducting polymer | Multi - walled carbon nanotubes | Rice wine | Pattern recognition |
مقاله انگلیسی |
10 |
ارتعاشات نانولولههای متخلخل
سال انتشار: 2018 - تعداد صفحات فایل pdf انگلیسی: 13 - تعداد صفحات فایل doc فارسی: 27 در این مطالعه رفتارهای ارتعاشی نانولولههای متخلخل برای اولین بار مورد بررسی قرار گرفته است. نظریه گرادیان کرنش غیر محلی در رابطه با یک مدل تیر اصلاحشده برای تدوین مدل وابسته به اندازه استفاده شده است. فرض بر این است که نانولولههای متخلخل از مواد هدفمند ساخته شدهاند و پارامترهای مواد نانولولهها به تغییرات دما وابسته هستند و همواره در جهت شعاعی متغیرند. با استفاده از نظریه تیر اصلاحشده که شامل اثرات دگردیس پذیری برش عرضی است، معادلات حرکت بر اساس اصل تنوع همیلتون و حل آن توسط روش حل ناویر به دست میآیند. برخی از مقایسهها صحت روش راهحل فعلی را تأیید میکنند. اثرات پارامتر غير محلی، پارامتر گراديان کرنش، تغييرات دما، کسر حجمی تخلخل و تغييرات ماده در ویژگیهای ارتعاش نانولولهها بهطور مفصل مورد بحث قرار گرفتهاند.
کليدواژگان: مواد هدفمند | ارتعاش | نانولولهها | نظریه گراديان کرنش غیر محلی | مواد متخلخل |
مقاله ترجمه شده |