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Article
Publication date: 1 June 2021

Peerzada Mudasir and Javed Ahmed Naqash

The aim of this research is to study the role and formation of hydration products particularly crystalline portlandite Ca(OH)2 in MWCNT-reinforced concrete at 28 days…

Abstract

Purpose

The aim of this research is to study the role and formation of hydration products particularly crystalline portlandite Ca(OH)2 in MWCNT-reinforced concrete at 28 days. Concrete is the largest manufactured building material in world in which cement, sand aggregates and water cement ratio plays governing role. Water–Cement ratio decides it strength, usage, serviceability and durability. As strength of concrete depends on formation of crystalline hydrates; therefore, water–cement ratio can alter formation of hydrates also. Unfortunately, concrete is the most brittle material and to overcome brittleness of conventional concrete is tailored with some fibers. Till now, multiwalled carbon nano tubes are the most tensile and strongest materials discovered. Addition of multiwalled carbon nano tubes changes basic properties of conventional concrete. Therefore, it is important to evaluate formation of crystalline hydrates in multiwalled carbon nano tube–reinforced concrete by micro structure analysis.

Design/methodology/approach

Till now, multiwalled carbon nano tube–reinforced concrete has not been analyzed at micro structure level. To accomplish the objective, four concrete mixes with 0.45, 0.48, 0.50 and 0.55 water–cement ratio having 0.5 and 1% multiwalled carbon nano tubes incorporated by weight of cement, respectively. For hardening property analysis, compressive strength was obtained by crushing cubes; flexural strength was obtained by three-point loading; and split tensile strength was obtained by splitting cylindrical specimens. For analyzing role and formation of crystalline portlandite Ca(OH)2 hydrates, X-ray diffraction test was conducted on 75-µ dust of each mix. Scanning electron microscopy analysis was performed on fractured samples of crushed cubes of multiwalled carbon nano tube–reinforced concrete samples to check aggloremation.

Findings

It was observed multiwalled carbon nano tubes successfully enhanced compressive strength, flexural strength and split tensile strength by 8.89, 5.33 and 28.90%, respectively, in comparison to reference concrete at 0.45 water–cement ratio and 0.5% multiwalled carbon nano tubes by weight of cement. When its content was increased from 0.5 to 1% by weight of cement compressive strength, flexural strength and split tensile strength diminished by 2.04, 0.32 and 1.18%, respectively, at 0.45 water–cement ratio. With the increment of water–cement ratio, overall strength decreased in all mixes, but in multiwalled carbon nano tube–reinforced concrete mixes, strength was more than reference mixes. In reference, concrete at 0.45 water–cement ratio crystalline portlandite Ca(OH)2 crystals are of nano metre size, but in carbon nano tube–reinforced concrete mix having 0.45 water–cement ratio and 0.5% multiwalled carbon nano tubes by weight of cement, its size is much smaller than reference mix, thereby enhancing mechanical strength. In reference, concrete at 0.55 water–cement ratio size of crystalline portladite Ca(OH)2 crystals is large, but with incorporation of multiwalled carbon nano tubes, their size reduced, thereby enhancing mechanical strength of carbon nano tube–reinforced concrete having 0.55 water–cement ratio and 0.5 and 1% multiwalled carbon nano tubes by weight of cement, respectively. Also at 1% multiwalled carbon nano tubes by weight of cement, agglomeration and reduction in formation of crystalline portlandite Ca(OH)2 crystals were observed. Multiwalled carbon nano tubes effectively refine pores and restrict propagation of micro cracks and act as nucleation sites for Calcium-Silicate-Hydrate phase. Geometry of crystalline axis of fracture for portlandite Ca(OH)2 crystals is altered with incorporation of multiwalled carbon nano tubes. Crystalline portlandite Ca(OH)2 crystals and bridging effect of multiwalled carbon nano tubes is governing factor for enhancing strength of multiwalled carbon nano tube reinforced concrete.

Practical implications

Multiwalled carbon nano tube–reinforced concrete can be used to make strain sensing concrete.

Originality/value

Change in geometry and size of axis of fracture of crystalline portladite Ca(OH)2 crystals with incorporation of multiwalled carbon nano tubes.

Details

World Journal of Engineering, vol. 18 no. 6
Type: Research Article
ISSN: 1708-5284

Keywords

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Article
Publication date: 11 October 2020

Mudasir Peerzada and Javed Ahmed Naqash

In cold areas, frost damage is the main factor for diminution of durability and serviceability of structures. Due to incessant freeze thaw regimes, micro cracks spread and…

Abstract

Purpose

In cold areas, frost damage is the main factor for diminution of durability and serviceability of structures. Due to incessant freeze thaw regimes, micro cracks spread and deteriorate concrete to point of failure.

Design/methodology/approach

The study aims to evaluate the fresh and hardened properties of concrete after thirty freeze-thaw cycles tailored with carbon nano tubes. For this purpose, samples with 0.4, 0.45, 0.48, 0.5 and 0.55 water cement ratio while 0.5 and 1% carbon nano tube (CNT) content by weight of cement were prepared.

Findings

At 0.48 water cement ratio and 0.5% CNT by weight of cement workability reduced by 37% and water absorption reduced by 0.04%. But compressive strength, split tensile strength and flexural strength increased by 15.38, 33.02 and 15.75%, respectively, after 30 freeze thaw cycles. Also, weight loss reduced with addition of 0.5% CNT by weight of cement after freeze thaw cycles.

Originality/value

Novelty of this research is to tailor traditional concrete with new materials.

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Article
Publication date: 5 May 2015

Kh.S. Karimov, Nisar Ahmed, M. Mehran Bashir, Fakhra Aziz, M.Zeeshan Rizvi, Adam Khan, M. Tahir, Nayyer Abbas Zaidi, Muhammad Hafeez and Arshad Saleem Bhatti

The purpose of this paper is to fabricate and investigate sensing properties of a novel, flexible resistive tensile load cells based on multi-walled carbon nano-tubes

Abstract

Purpose

The purpose of this paper is to fabricate and investigate sensing properties of a novel, flexible resistive tensile load cells based on multi-walled carbon nano-tubes (MWCNTs)/rubber composites. The use of carbon nanotubes makes it very attractive for being used as sensors.

Design/methodology/approach

On thin rubber substrate, MWCNTs powder was deposited and pressed at elevated temperature. Two types of samples were prepared: first sample was made by depositing MWCNTs suspension in water on the substrate, then the sample was dried at room temperature; the second sample was prepared by applying dry MWCNTs powder directly on the substrate.

Findings

The resistances of the cells made from wet MWCNT powder are much lower than those made with dry powder. It was found that the fabricated load cells were highly sensitive to the force and showed good repeatability. The resistance of the flexible resistive tensile MWCNTs/rubber composite load cells increased 1.37 times, on average, with the increasing force (up to 0.045 N). The sensitivity of the cells was equal to 142 N-1.

Practical implications

The device fabrication method used here provides a simple, less expensive and effective approach for preparing resistive tensile load cells.

Originality/value

A novel, flexible resistive tensile load cells using MWCNTs/rubber composites have been successfully fabricated and investigated. MWCNTs, in dry and wet form, have been deposited on thin rubber substrates by adopting a very simple and inexpensive technique.

Details

Pigment & Resin Technology, vol. 44 no. 3
Type: Research Article
ISSN: 0369-9420

Keywords

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Article
Publication date: 1 February 2015

M. K. Sinha, B. R. Das, A. Srivastava and A. K. Saxena

The electrospinng of PAN and PAN/CNT composite webs is carried out with the commercially available Nanospider machine. The webs are spun under similar processes and coated…

Abstract

The electrospinng of PAN and PAN/CNT composite webs is carried out with the commercially available Nanospider machine. The webs are spun under similar processes and coated on Polypropylene spun bonded nonwoven fabric. This research work reports on the influence of multi-walled carbon nano tube (MWCNT) on the morphology, tensile properties, conductivity, thermal, chemical and crystalline structure of PAN and PAN/CNT composite nanofibrous webs. The morphological developments are explained on the basis of nanofibre diameter and web density as depicted by FESEM images. An addition of CNT greatly affects the morphology of webs, increases fibre diameter, decreases web density and leads to a roughened web surface. The mechanical properties of PAN /CNT composite webs are also found to be influenced by CNT concentration. The addition of MWCNT to PAN enhances the conductive properties of webs. The specific conductivity of PAN/CNT composite webs is found to be in order of 10-6 S/cm, which falls in the semiconducting regime and follows Ohm's law of conductivity. The TGA plots confirmed that the PAN/CNT composite web is more thermally stable than the PAN web. The presence of CNT in the polymer matrix is evidenced by D and G band, indicating a successful electrospun coating process.

Details

Research Journal of Textile and Apparel, vol. 19 no. 1
Type: Research Article
ISSN: 1560-6074

Keywords

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Article
Publication date: 8 April 2021

Abdulrahman Al-Shami, Rami Joseph Oweis and Mohamed Ghazi Al-Fandi

This paper aims to report on the development of a novel electrochemical amperometric immunosensor to diagnose early hepatocellular carcinoma (HCC) by detecting the Midkine…

Abstract

Purpose

This paper aims to report on the development of a novel electrochemical amperometric immunosensor to diagnose early hepatocellular carcinoma (HCC) by detecting the Midkine (MDK) biomarker.

Design/methodology/approach

Anti-Midkine antibodies were immobilized covalently through carbodiimides chemistry on carbon screen-printed electrodes modified with carboxylated multi-walled carbon nanotubes. The development process was characterized using cyclic voltammetry, electrochemical impedimetric spectroscopy, Fourier transform infrared spectroscopy and atomic force microscopy. Differential pulse voltammetry was used to investigate the immunosensor performance in detecting MDK antigen within the concentration range of 1 pg/ml to 100 ng/ml.

Findings

MDK immunosensor exhibited high sensitivity and linearity with a detection limit of 0.8 pg/ml and a correlation coefficient of 0.99. The biosensor also demonstrated high selectivity, stability and reproducibility.

Originality/value

The developed MDK immunosensor could be a promising tool to diagnose HCC and reduce the number of related deaths.

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Article
Publication date: 27 January 2021

Irina Tatiana Garces and Cagri Ayranci

A review on additive manufacturing (AM) of shape memory polymer composites (SMPCs) is put forward to highlight the progress made up to date, conduct a critical review and…

Abstract

Purpose

A review on additive manufacturing (AM) of shape memory polymer composites (SMPCs) is put forward to highlight the progress made up to date, conduct a critical review and show the limitations and possible improvements in the different research areas within the different AM techniques. The purpose of this study is to identify academic and industrial opportunities.

Design/methodology/approach

This paper introduces the reader to three-dimensional (3 D) and four-dimensional printing of shape memory polymers (SMPs). Specifically, this review centres on manufacturing technologies based on material extrusion, photopolymerization, powder-based and lamination manufacturing processes. AM of SMPC was classified according to the nature of the filler material: particle dispersed, i.e. carbon, metallic and ceramic and long fibre reinforced materials, i.e. carbon fibres. This paper makes a distinction for multi-material printing with SMPs, as multi-functionality and exciting applications can be proposed through this method. Manufacturing strategies and technologies for SMPC are addressed in this review and opportunities in the research are highlighted.

Findings

This paper denotes the existing limitations in the current AM technologies and proposes several directions that will contribute to better use and improvements in the production of additive manufactured SMPC. With advances in AM technologies, gradient changes in material properties can open diverse applications of SMPC. Because of multi-material printing, co-manufacturing sensors to 3D printed smart structures can bring this technology a step closer to obtain full control of the shape memory effect and its characteristics. This paper discusses the novel developments in device and functional part design using SMPC, which should be aided with simple first stage design models followed by complex simulations for iterative and optimized design. A change in paradigm for designing complex structures is still to be made from engineers to exploit the full potential of additive manufactured SMPC structures.

Originality/value

Advances in AM have opened the gateway to the potential design and fabrication of functional parts with SMPs and their composites. There have been many publications and reviews conducted in this area; yet, many mainly focus on SMPs and reserve a small section to SMPC. This paper presents a comprehensive review directed solely on the AM of SMPC while highlighting the research opportunities.

Details

Rapid Prototyping Journal, vol. 27 no. 2
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 2 October 2007

Won‐Shik Chu, Sung‐Geun Kim, Woo‐Kyun Jung, Hyung‐Jung Kim and Sung‐Hoon Ahn

The purpose of this research, is to develop a nano composite deposition system (NCDS) to fabricate three dimensional functional nano composite parts.

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Abstract

Purpose

The purpose of this research, is to develop a nano composite deposition system (NCDS) to fabricate three dimensional functional nano composite parts.

Design/methodology/approach

The NCDS is a hybrid system in which material removal process by mechanical micro machining and/or the deposition process is combined.

Findings

Hybrid RP technology showed higher precision than those made by casting or deposition process. Tensile strength of the hydroxyapatite‐acrylic composite was about four times higher than that of resin‐only specimen while MWCNT composite did not show much improvement.

Originality/value

The paper illustrates new approaches for rapid prototyping techniques with various materials and high precision.

Details

Rapid Prototyping Journal, vol. 13 no. 5
Type: Research Article
ISSN: 1355-2546

Keywords

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Article
Publication date: 4 March 2014

Ayush Jain, Imbesat Hassan Rizvi, Subrata Kumar Ghosh and P.S. Mukherjee

Nanofluids exhibit enhanced heat transfer characteristics and are expected to be the future heat transfer fluids particularly the lubricants and transmission fluids used…

Abstract

Purpose

Nanofluids exhibit enhanced heat transfer characteristics and are expected to be the future heat transfer fluids particularly the lubricants and transmission fluids used in heavy machinery. For studying the heat transfer behaviour of the nanofluids, precise values of their thermal conductivity are required. For predicting the correct value of thermal conductivity of a nanofluid, mathematical models are necessary. In this paper, the effective thermal conductivity of various nanofluids has been reported by using both experimental and mathematical modelling. The paper aims to discuss these issues.

Design/methodology/approach

Hamilton and Crosser equation was used for predicting the thermal conductivities of nanofluids, and the obtained values were compared with the experimental findings. Nanofluid studied in this paper are Al2O3 in base fluid water, Al2O3 in base fluid ethylene glycol, CuO in base fluid water, CuO in base fluid ethylene glycol, TiO2 in base fluid ethylene glycol. In addition, studies have been made on nanofluids with CuO and Al2O3 in base fluid SAE 30 particularly for heavy machinery applications.

Findings

The study shows that increase in thermal conductivity of the nanofluid with particle concentration is in good agreement with that predicted by Hamilton and Crosser at typical lower concentrations.

Research limitations/implications

It has been observed that deviation between experimental and theoretical results increases as the volume concentration of nanoparticles increases. Therefore, the mathematical model cannot be used for predicting thermal conductivity at high concentration values.

Originality/value

Studies on nanoparticles with a standard mineral oil as base fluid have not been considered extensively as per the previous literatures available.

Details

Industrial Lubrication and Tribology, vol. 66 no. 2
Type: Research Article
ISSN: 0036-8792

Keywords

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Article
Publication date: 11 November 2013

Andrea G. Chiariello, Carlo Forestiere, Giovanni Miano and Antonio Maffucci

Nowadays, nano-antennas or nanoscale absorbers made by innovative materials such as carbon nanotubes are gaining more and more interest, because of their outstanding…

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1188

Abstract

Purpose

Nowadays, nano-antennas or nanoscale absorbers made by innovative materials such as carbon nanotubes are gaining more and more interest, because of their outstanding features. The purpose of this paper is to investigate the scattering properties of carbon nanotubes, either isolated or arranged in arrays. The peculiar behaviour of such innovative materials is studied, taking also into account the finite length of the structure and the dependence of the scattering field from the operating temperature.

Design/methodology/approach

First a model is presented for the electrical transport along the carbon nanotubes, based on Boltzmann quasi-classical transport theory. The model includes quantistic and inertial phenomena observed in the carbon nanotube electrodynamics. The model also includes the effects of temperature. Using this electrodynamical model, the electromagnetic formulation of the scattering problem is cast in terms of a Pocklington-like equation. The numerical solution is obtained by means of the Galerkin method, with special care in handling the logarithmic singularity of the kernel. Case studies are carried out, either referred to isolated single-wall carbon nanotubes (SWCNTs) and array of SWCNTs.

Findings

The scattering properties of SWCNT are strongly influenced by the temperature and by the distance between the tubes. As temperature increases, the amplitude of the resonance peaks decreases, at a rate which is double the rate of changes of temperature. The resonance frequencies are insensitive to temperature. As for the distance between the tubes in an array, it influence the scattering resonance introducing a shift in the resonance frequencies which is appreciable for distances lower than the semi-length of the CNT. For higher distances the CNT scattered field may be regarded as the sum of the fields emitted by each CNT, as if they were isolated.

Research limitations/implications

As far as now only SWCNTs have been studied. The multi-wall carbon nanotubes would show a richer behaviour with temperature, due to the joint effect of reduction of the mean free path and increase of the number of conducting channels, as temperature increases.

Practical implications

Possible use of carbon nanotubes as absorbing material or scatterers.

Originality/value

The model presented here is based on a self-consistent and physically meaningful description of the CNT electrodynamics, which takes rigorously into account the effect of temperature, size and chirality of each CNT.

Details

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, vol. 32 no. 6
Type: Research Article
ISSN: 0332-1649

Keywords

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Article
Publication date: 17 June 2019

Ehsan Gholamalizadeh, Farzad Pahlevanzadeh, Kamal Ghani, Arash Karimipour, Truong Khang Nguyen and Mohammad Reza Safaei

This study aims to numerically study the forced convection effects on a two-dimensional microchannel filled with a porous material containing the water/FMWCNT nanofluid…

Abstract

Purpose

This study aims to numerically study the forced convection effects on a two-dimensional microchannel filled with a porous material containing the water/FMWCNT nanofluid. The upper and lower microchannel walls were fully insulated thermally along 15 per cent of their lengths at each end of the microchannel, with the in-between length being exposed to a constant temperature. The slip velocity boundary condition was applied along the microchannel walls.

Design/methodology/approach

The Navier–Stokes equations were discretized before being solved numerically via a FORTRAN computer code. The following ranges were considered for the studied parameters: slip factor (B) equal to 0.001, 0.01 and 0.1; Reynolds number (Re) between 10 and 100; solid nanoparticle mass fraction (ϕ) between 0.0012 and 0.0025; Darcy number (Da) between 0.001 and 0.1; and porosity factor (ε) between 0.4 and 0.9.

Findings

Increasing the Da caused a greater increase in the velocity profile than increasing Re, whereas increasing porosity did not affect the velocity profile growth at all.

Originality/value

This paper is the continuation of the authors’ previous studies. Using the water/FMWCNT nanofluid as the working fluid in microchannels is among the achievements of this study.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 30 no. 5
Type: Research Article
ISSN: 0961-5539

Keywords

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