scholarly journals Response of Nano-Reinforced Cementitious Composites Using Natural and Commercial Dispersants

Proceedings ◽  
2019 ◽  
Vol 34 (1) ◽  
pp. 23
Author(s):  
Anwari ◽  
Khushnood ◽  
Ahmad ◽  
Muhammad ◽  
Tulliani
Keyword(s):  
Ultra Violet ◽  
Weight Percent ◽  
Point Of View ◽  
Modulus Of Rupture ◽  
Experimental Investigations ◽  
Early Age ◽  
Natural Surfactant ◽  
The Matrix ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

An efficient and promising approach from economy point of view to effectively disperse Multi-walled carbon nanotubes (MWCNTs) in cementitious environment has been devised. The natural organic extract from species of indigenously known ‘keekar’ trees scattered along tropical and sub-tropical countries; is found as an exceptional replacement to the non-natural commercial surfactant. In the initial phase ideal content of surfactant was explored in relation with the added content of MWCNTs using ultra-violet spectroscopy. The experimental investigations were then extended to five formulations containing 0.0, 0.025, 0.05, 0.08 and 0.10 MWCNTs by weight percent of cement. It was observed that the natural surfactant produced efficient dispersion at much reduced cost (>14% approx.) compared with the commercial alternate. The estimated weight efficiency factor ‘ϕ’ was found 6.5 times higher by the proposed sustainable replacement to the conventional with remarkable increase of 23% in modulus of rupture on 0.08 wt% addition of MWCNTs. Besides, strength enhancement the dispersed MWCNTs also improved the first crack and ultimate fracture toughness by 51.5% and 35.9%, respectively. The field emission scanning electron microscopy of the cryofractured samples revealed efficient dispersion of MWCNTs in the matrix leading to the phenomenon of effective crack bridging and crack branching in the composite matrix. Furthermore, the proposed scheme significantly reduced the early age volumetric shrinkage by 39% to mitigate early age micro-cracks encouraging long lasting deteriorations from durability prospects.

scholarly journals A Novel Composite with Structural Health Monitoring Functionality via 2D and 3D Impedance Mapping Topography

2021 ◽  
Vol 11 (4) ◽  
pp. 1647
Author(s):  
Georgios Foteinidis ◽  
Alkiviadis S. Paipetis
Keyword(s):  
Structural Health Monitoring ◽  
Health Monitoring ◽  
Structural Integrity ◽  
Carbon Fabric ◽  
Structural Health ◽  
The Matrix ◽  
Junction Points ◽  
Sinusoidal Electric Field ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

We report the transformation of a conventional composite material into a multifunctional structure able to provide information about its structural integrity. A purposely positioned grid of carbon fabric strips located within a glass fibre laminate in alternating 0/90 configuration combined with a ternary nanomodified epoxy matrix imparted structural health monitoring (SHM) topographic capabilities to the composite using the impedance spectroscopy (IS) technique. The matrix was reinforced with homogenously dispersed multi-walled carbon nanotubes (MWCNTs) and carbon black (CB). A sinusoidal electric field was applied locally over a frequency range from 1 Hz to 100 kHz between the junction points of the grid of carbon fabric strips. The proposed design enabled topographic damage assessment after a high-velocity impact via the local monitoring of the impedance. The data obtained from the IS measurements were depicted by magnitude and phase delay Bode plots and Nyquist plots. The impedance values were used to create a 2D and a multi-layer (3D) contour topographical image of the damaged area, which revealed crucial information about the structural integrity of the composite.

Study on Electrochemical Hydrogen Storage of Multi-Walled Carbon Nanotubes

2007 ◽  
Vol 26-28 ◽  
pp. 831-834 ◽  
Author(s):  
Lei Xie ◽  
Xiao Qi Li
Keyword(s):  
Carbon Nanotubes ◽  
Hydrogen Storage ◽  
Storage Capacity ◽  
Weight Percent ◽  
Chemical Form ◽  
Hydrogen Storage Capacity ◽  
Electrochemical Hydrogen Storage ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes ◽  
Discharging Capacity

The electrode(Ni-MWNTs) containing nickel(Ni) and multi-walled carbon nanotubes (MWNTs) was prepared by composite electrodeposit. Electrochemical hydrogen storage of the electrode was studied. The result showed a high electrochemical discharging capacity of up to 1361.1mA·h·g-1, which corresponds to a hydrogen storage capacity of 4.77Wt%(weight percent). Test of cyclic lifespan showed MWNTs had certain cyclic lifespan. Cyclic voltammetry tests showed that MWNTs can store hydrogen in chemical form.

An integrated numerical–experimental study on the optimum utilization of carbon nanotubes in laminated composites

2016 ◽  
Vol 19 (2) ◽  
pp. 231-258 ◽  
Author(s):  
Mahmood Heshmati ◽  
Bandar Astinchap ◽  
Masoud Heshmati ◽  
Mohammad Hosein Yas ◽  
Yasser Amini
Keyword(s):  
Carbon Nanotubes ◽  
Natural Frequency ◽  
Experimental Studies ◽  
Distribution Patterns ◽  
Weight Percent ◽  
Composite Beams ◽  
Linear Distribution ◽  
Fundamental Natural Frequency ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

In this paper, a set of numerical and experimental studies are performed to improve mechanical and vibrational properties of carbon nanotubes-reinforced composites. First, at a design concept level, linear distribution patterns of multi-walled carbon nanotubes through the thickness of a typical beam is adopted to investigate its fundamental natural frequency for a given weight percent of multi-walled carbon nanotubes. Both Timoshenko and Euler-Bernoulli beam theories are used in the derivation of the governing equations. The finite element method is employed to obtain a numerical approximation of the motion equation. Next, based on the introduced distribution patterns, laminated multi-walled carbon nanotubes-reinforced polystyrene-amine composite beams are fabricated. Static and experimental modal tests are performed to measure the effective stiffness and fundamental natural frequencies of the fabricated composite beams. Also, in order to generate realistic model to investigate the material properties of fabricated composite beams, the actual tensile specimens of multi-walled carbon nanotubes/polystyrene-amine composites are successfully fabricated and the tensile behaviors of both pure matrix and composites are investigated. To better interfacial bonding between carbon nanotubes and polymer, a chemical treatment is performed on carbon nanotubes. It is seen that the addition of a few wt. % of multi-walled carbon nanotubes make considerable increase in the Young's modulus and the tensile strength of the composite. It is observed from the free vibration tests that the uniform distribution of multi-walled carbon nanotubes results in an increase of 9.5% in the fundamental natural frequency of the polymer cantilever beam, whereas using the symmetric multi-walled carbon nanotube distribution increased its fundamental natural frequency by 17.32%.

Capillary Effect of Multi-Walled Carbon Nanotubes Suspension in Composite Processing

2008 ◽  
Vol 8 (4) ◽  
pp. 1669-1678
Author(s):  
Zhihang Fan ◽  
Suresh G. Advani
Keyword(s):  
Carbon Nanotubes ◽  
Interlaminar Shear Strength ◽  
Fiber Bundles ◽  
High Permeability ◽  
Fiber Preform ◽  
Capillary Action ◽  
The Matrix ◽  
Multi Walled Carbon Nanotubes ◽  
Interlaminar Shear ◽  
Walled Carbon Nanotubes

Carbon nanotubes (CNTs) do have the potential to improve the interlaminar shear strength (ILSS) of composites if they can be successfully integrated into the matrix as it infuses into the fiber preform. The infusion under capillary action of Multi-Walled Carbon Nanotubes (MWNT)/Epoxy suspension with tubes of length 0.3∼1 μm in glass fiber bundles containing pores of the order of 5 nm∼100 μm was investigated. The influence of parameters such as suspension concentration, viscosity, porous media architecture, surface tension and contact angle were explored. It was found that filtering of the suspension is a major challenge for uniform infusion for concentrations beyond 0.5% MWNT by weight. This is even truer for fiber bundles that are compacted. Hence for successful manufacturing, new infusion techniques that rely on fabrics of high permeability will have to be developed to fabricate such nanocomposites.

Acylchloride-Functionalized Multiple-Walled Carbon Nanotubes Reinforced Polyimide for High Dielectric Properties

2011 ◽  
Vol 239-242 ◽  
pp. 2655-2658
Author(s):  
Heng Feng Li ◽  
Guo Wen He ◽  
Jun Li ◽  
Jun Chen ◽  
Jiang Cong Chen
Keyword(s):  
Carbon Nanotubes ◽  
Composite Films ◽  
Dielectric Constants ◽  
Acid Mixture ◽  
Mass Fractions ◽  
The Matrix ◽  
Multi Walled Carbon Nanotubes ◽  
Polyimide Matrix ◽  
High Dielectric ◽  
Walled Carbon Nanotubes

A series of polyimide composites with various mass fractions of multi-walled carbon nanotubes (MWNTs) were prepared by in situ polymerization. MWNTs were treated with an acid mixture and sulfoxide chloride in turn to increase the chemical compatibility of carbon nanotubes with the polyimide matrix. The modified MWNTs are dispersed homogeneously in the matrix while the structure of the PI and MWNTs structures are stable in the preparation process. The composite films hold preferable thermal stability as same as the pure PI. The dielectric constants of the composites decreased with the increasing frequency and increase sharply with the adding of MWNTs.

scholarly journals Chitosan Grafted Carbon Nanotubes Reinforced Vinyl Ester/UPE Blend Based Partially Bio-Nanocomposite

2019 ◽  
Vol 31 (9) ◽  
pp. 1943-1948
Author(s):  
Priyabrata Mohanty ◽  
Tapan Kumar Bastia ◽  
Dibakar Behera ◽  
Shivkumari Panda
Keyword(s):  
Carbon Nanotubes ◽  
Vinyl Ester ◽  
Unsaturated Polyester ◽  
Homogeneous Distribution ◽  
Swelling Properties ◽  
The Matrix ◽  
Multi Walled Carbon Nanotubes ◽  
Enhanced Properties ◽  
Walled Carbon Nanotubes

This work represents the preparation and characterization of some unique properties of vinyl ester (VE) and unsaturated polyester (UPE) blend based nanocomposites by introducing biopolymer chitosan grafted multi-walled carbon nanotubes (MWCNTs). Initially, surface grafting of MWCNTs with chitosan was performed by utilizing glutaraldehyde as a cross linking reagent through covalent deposition method and are successfully characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy(SEM). Then 50:50 wt % of vinyl ester and unsaturated polyester blend was prepared by simple sonication method. Three different specimens of VE/UPE/CS-g-MWCNTs nanocomposites were fabricated with addition of 1, 3 and 5 wt % of functionalized bionanofiller. Chitosan grafting of MWCNTs offered enhanced properties to the nanocomposites suggesting homogeneous distribution of the nanofiller in the matrix with minimum corrosion and swelling properties. 3 wt % of functionalized bionanofiller loading showed superior essential characteristics and after that the properties reduced may be due to the nucleating tendency of the nanofiller particles.

Investigation on the Reinforcement of Multi-Walled Carbon Nanotubes on Alumina Matrix

2006 ◽  
Vol 51 ◽  
pp. 64-67
Author(s):  
Jing Sun ◽  
Lian Gao
Keyword(s):  
Carbon Nanotubes ◽  
Bending Strength ◽  
Weight Percent ◽  
Processing Route ◽  
Matrix Composites ◽  
Alumina Matrix ◽  
Multi Walled Carbon Nanotubes ◽  
Alumina Composites ◽  
Walled Carbon Nanotubes ◽  
Monolithic Alumina

In this paper, a colloidal processing route was adopted to disperse multi-walled carbon nanotubes (MWNTs) into alumina powders homogenously. Alumina matrix composites containing 0.1 to 2 weight percent of MWNTs were successfully fabricated by pressureless sintering. Also, 1wt% MWNTs-alumina composites were prepared by hot pressing for comparison. It was found that when the sample was sintered at 1450oC, the addition of 1wt% carbon nanotubes led to 10% increase in bending strength compared with monolithic alumina. The reinforcement mechanism was discussed based on the microstructure investigation. The broken nanotubes and pullout of MWNTs at interfaces are efficient in transferring the load from the alumina matrix to the nanotubes, leading to the improvement of the mechanical properties.

Development of nanocomposite coatings with improved mechanical, thermal, and corrosion protection properties

2017 ◽  
Vol 52 (8) ◽  
pp. 1045-1060 ◽  
Author(s):  
Majid TabkhPaz ◽  
Dong-Yeob Park ◽  
Patrick C Lee ◽  
Ron Hugo ◽  
Simon S Park
Keyword(s):  
Carbon Nanotubes ◽  
Thermal Expansion ◽  
Coefficient Of Thermal Expansion ◽  
Composite Coatings ◽  
Scratch Resistance ◽  
Gas Permeation ◽  
Graphene Nanoplatelets ◽  
The Matrix ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

In this study, new composite coatings are fabricated and investigated for their applications as the metal coating. The studied coatings consist of two-layered composites with various nanoparticulates as fillers in a polymeric matrix (styrene acrylic). The first layer bonded to the steel plate uses a combination of zinc particles, multi-walled carbon nanotubes, and graphene nanoplatelets. For the second layer, hexagonal boron nitride with high electrical insulation properties is added to the matrix. The morphology of the nanoparticulates is conducted using a scanning electron microscope. The coefficient of thermal expansion, cathodic disbondment resistance, gas penetration, and scratch resistance of the coatings are evaluated. The corroded area on the cathodic disbondment test specimens reduced down up to 90% for the composite with zinc (20 wt%), multi-walled carbon nanotubes (2 wt%), and graphene nanoplatelets (2 wt%), compared to a specimen coated with a pure polymer. It is seen that the presence of nanoparticulates decreased gas permeation and thermal expansion of the matrix by 75% and 65%, respectively. The addition of nanoparticulates also enhanced scratch resistance of the coating composites.

Esterification of wood with citric acid: The catalytic effects of sodium hypophosphite (SHP)

Holzforschung ◽  
2014 ◽  
Vol 68 (4) ◽  
pp. 427-433 ◽  
Author(s):  
Xinhao Feng ◽  
Zefang Xiao ◽  
Shujuan Sui ◽  
Qingwen Wang ◽  
Yanjun Xie
Keyword(s):  
Citric Acid ◽  
Treated Wood ◽  
Wood Properties ◽  
Weight Percent ◽  
Point Of View ◽  
Modulus Of Rupture ◽  
Sodium Hypophosphite ◽  
Esterification Reaction ◽  
Water Leaching ◽  
Efficient Catalyst

Abstract Sodium hypophosphite (SHP) has been recognized as the most efficient catalyst in the esterification reaction of cellulosic fabrics with citric acid (CA), but both the high cost and the environmentally harmful property of SHP call for optimization of its application. In this study poplar wood (Populus adenopoda Maxim.) was treated with CA to various weight percent gains (WPGs) and the effect of SHP on the resulting properties of treated wood was investigated. Esterification with CA can occur also in the absence of SHP, as evidenced by the resistance to water leaching of CA. Wood treated with CA alone to 36% WPG exhibited 7% bulking, 50% anti-swelling efficiency, 30% reductions of the modulus of rupture, and 50% lower impact strength. Treatments with CA in the presence of SHP provided wood properties comparable to wood treated with CA alone. Thus the application of SHP can be questioned from the point of view of an economic production and environmental protection.

Investigation of behaviors of glass/epoxy laminate composites reinforced with carbon nanotubes under quasi-static punch shear loading

2017 ◽  
Vol 21 (4) ◽  
pp. 1535-1556 ◽  
Author(s):  
Mohammad Sadeghi ◽  
Mohammad Hossein Pol
Keyword(s):  
Carbon Nanotubes ◽  
Contact Force ◽  
Glass Fibers ◽  
Shear Loading ◽  
Test Results ◽  
Absorbed Energy ◽  
Laminate Composites ◽  
The Matrix ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

In this paper, in addition to investigation of the effects of adding of nanotubes on the tensile properties of epoxy matrix and glass/epoxy laminate composite, the effects of adding of nanotubes and the effect of indenter shape on quasi-static punch shear properties of glass/epoxy laminate are experimentally studied. Laminate nanocomposites have 12 layers of plain weave glass fibers which are made by hand lay-up method. Resin is composed of a two-component epoxy; Epon 828 as the base and Epikure F-205 as the curing agent. Multi-walled carbon nanotubes modified by hydroxid (–COOH) are used with 0%, 0.5% and 1% ratio in weight with respect to the matrix. In quasi-static punch shear tests, three indenters (flat, conical and ogival) are utilized. Tensile test results for nanomatrix show that the most changes are obtained on 0.5 wt.% specimen, in which the ultimate strength and strain energy are increased 22% and 17% respect to the neat sample, respectively. No distinct change was observed in tensile behavior of the hybrid composite samples by the addition of carbon nanotubes. Punch shear test results show that addition of carbon nanotubes reduces the contact force and the absorbed energy in ogival and conical indenters. In presence of nanotube particles, the maximum decreasing in the contact force and the absorbed energy happens in conical nose indenter with 23% and 26% decrease, respectively. Comparison of different indenters shows that in the neat samples, the maximum and minimum contact force belongs to the flat nose indenter (2.45 kN) and the ogival nose indenter (0.75 kN), respectively, while the maximum and minimum absorbed energy belongs to the conical nose indenter (13.5 J) and the flat nose indenter (10 J), respectively. Moreover, change of indenter geometry changes the failure mechanism, so that the failure of flat indenter is plugging and failure of sharp indenter is petaling.

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