scholarly journals Improved mechanical and viscoelastic properties of CNT-composites fabricated using an innovative ultrasonic dual mixing technique

2020 ◽  
Vol 29 (1) ◽  
pp. 77-85
Author(s):  
Shailesh I. Kundalwal ◽  
Ankit Rathi
Keyword(s):  
Epoxy Matrix ◽  
Viscoelastic Properties ◽  
High Strength ◽  
Critical Issue ◽  
Tensile Fracture ◽  
Epoxy Nanocomposites ◽  
Multiwalled Carbon ◽  
Tensile Fracture Surface ◽  
Lap Shear ◽  
Uniform Dispersion

AbstractCarbon nanotube (CNT) acts as the most promising nanofiller due to its high aspect ratio and exceptional nanoscale-level properties. However, the dispersibility of CNTs in the conventional polymer matrices is a very critical issue in developing the high-strength and light-weight polymer-based nanocomposites. In this study, an attempt was made to develop cluster-free and uniform dispersion of multiwalled carbon nanotubes (MWCNTs) in the epoxy matrix using an innovative ultrasonic dual mixing technique. The effect of dispersion of MWCNTs on the mechanical and viscoelastic properties of MWCNT-epoxy nanocomposites was comprehensively studied. Our results reveal that the tensile strength and toughness of epoxy nanocomposites with 0.50 wt.% of MWCNTs improved by 21% and 46%, respectively, as compared to neat epoxy. The nanocomposite samples with the same CNT loading show maximum enhancements of 22% and 26% in the lap shear strength and storage modulus, respectively. The tensile fracture surface examination of MWCNT-epoxy nanocomposites using field emission scanning electron microscopy indicated the cluster-free and uniform dispersion of MWC-NTs in the epoxy matrix.

scholarly journals Mechanical and Water Uptake Properties of Epoxy Nanocomposites with Surfactant-Modified Functionalized Multiwalled Carbon Nanotubes

Nanomaterials ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1234
Author(s):  
Arya Uthaman ◽  
Hiran Mayookh Lal ◽  
Chenggao Li ◽  
Guijun Xian ◽  
Sabu Thomas
Keyword(s):  
Carbon Nanotubes ◽  
Thermal Properties ◽  
Water Uptake ◽  
Epoxy Matrix ◽  
Enhancement Effect ◽  
Mechanical And Thermal Properties ◽  
Epoxy Nanocomposites ◽  
Segmental Mobility ◽  
Multiwalled Carbon ◽  
Uniform Dispersion

The superior mechanical properties of multi-walled carbon nanotubes (MWCNTs) play a significant role in the improvement of the mechanical and thermal stability of an epoxy matrix. However, the agglomeration of carbon nanotubes (CNTs) in the epoxy is a common challenge and should be resolved to achieve the desired enhancement effect. The present paper investigated the thermal, mechanical, and water uptake properties of epoxy nanocomposites with surfactant-modified MWCNTs. The nanocomposites were prepared through the incorporation of different weight concentrations of MWCNTs into the epoxy matrix. Comparative analysis of neat epoxy and epoxy/CNT nanocomposites were conducted through thermal, mechanical, microscopic, and water uptake tests to reveal the improvement mechanism. The homogenous distribution of the CNTs in the epoxy was achieved by wrapping the surfactant onto the CNTs. The addition of surfactant-modified CNTs into the epoxy caused an obvious increase in the mechanical and thermal properties. This improvement mechanism could be attributed to the uniform dispersion of the CNTs in the epoxy matrix reducing the free volume between the polymer chains and restricting the chain segmental mobility, leading to strong interfacial bonding and an efficient load transfer capability between the CNTs and the epoxy matrix. However, the mechanical and thermal properties of the epoxy/CNT nanocomposite decreased owing to the agglomeration effect when the concentration of the CNTs exceeded the optimal percentage of 1.5%. Additionally, the CNTs could impart a reduction in the wettability of the surface of the epoxy/CNT nanocomposite, leading to the increase in the contact angle and a reduction in the water uptake, which was significant to improve the durability of the epoxy. Moreover, the higher weight concentration (2%) of the CNTs showed a greater water uptake owing to agglomeration, which may cause the formation of plenty of microcracks and microvoids in the nanocomposite.

Characterization of Mechanical and Viscoelastic Properties of SC-15 Epoxy Nanocomposites Reinforced With Multi-Walled Carbon Nanotubes, Nanoclay and Binary Nanoparticles

2014 ◽  
Author(s):  
Tanjheel H. Mahdi ◽  
Mohammad E. Islam ◽  
Mahesh V. Hosur ◽  
Alfred Tcherbi-Narteh ◽  
S. Jeelani
Keyword(s):  
Carbon Nanotubes ◽  
Epoxy Resin ◽  
Viscoelastic Properties ◽  
Flexural Modulus ◽  
Epoxy Nanocomposites ◽  
Multiwalled Carbon ◽  
Epoxy Resin System ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes ◽  
Binary Nanoparticles

Mechanical and viscoelastic properties of polymer nanocomposites reinforced with carboxyl functionalized multiwalled carbon nanotubes (COOH-MWCNT), montmorillonite nanoclays (MMT) and MWCNT/MMT binary nanoparticle were investigated. In this study, 0.3 wt. % of COOH-MWCNT, 2 wt. % of MMT and 0.1 wt. % COOH-MWCNT/2 wt. % MMT binary nanoparticles by weight of epoxy were incorporated to modify SC-15 epoxy resin system. The nanocomposites were subjected to flexure test, dynamic mechanical and thermomechanical analyses. Morphological study was conducted with scanning electron microscope. Addition of each of the nanoparticles in epoxy showed significant improvement in mechanical and viscoelastic properties compared to those of control ones. But, best results were obtained for addition of 0.1% MWCNT/2% MMT binary nanoparticles in epoxy. Nanocomposites modified with binary nanoparticles exhibited about 20% increase in storage modulus as well as 25° C increase in glass transition temperature. Flexural modulus for binary nanoparticle modified composites depicted about 30% improvement compared to control ones. Thus, improvement of mechanical and viscoelastic properties was achieved by incorporating binary nanoparticles to epoxy nanocomposites. The increase in properties was attributed to synergistic effect of MWCNTs and nanoclay in chemically interacting with each other and epoxy resin as well as in arresting and delaying the crack growth once initiated.

MICROSTRUCTURE AND RESISTIVITY OF CARBON NANOTUBE AND NANOFIBER/EPOXY MATRIX NANOCOMPOSITE

2002 ◽  
Vol 01 (05n06) ◽  
pp. 719-723 ◽  
Author(s):  
JIN-HONG DU ◽  
ZHE YING ◽  
SHUO BAI ◽  
FENG LI ◽  
CHAO SUN ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Epoxy Matrix ◽  
Single Walled Carbon Nanotubes ◽  
Epoxy Nanocomposites ◽  
Multiwalled Carbon ◽  
Pure Epoxy ◽  
The Matrix ◽  
Walled Carbon Nanotubes ◽  
Matrix Nanocomposites ◽  
Matrix Nanocomposite

Single-walled carbon nanotubes (SWNTs), multiwalled carbon nanotubes (MWNTs) and vapor-grown carbon nanofibers (VGCNFs)/epoxy matrix nanocomposites were prepared, respectively. The microstructure of the nanocomposites was observed by SEM and the resistivities of the nanocomposites with different concentration of CNTs/VGCNFs were measured. Based on the experimental results, the dispersion of SWNTs and MWNTs were relatively poor but that of VGCNFs is uniform within the matrix. The resistivitiy of pure epoxy is about 1010.5Ω · cm and several orders of magnitude higher than those of SWNT, MWNT and VGCNF/epoxy nanocomposites. The resistivities of the nanocomposites drop with the increase of the CNTs/VGCNFs content in the matrix and the resistivity of VGCNFs/epoxy nanocomposites was much lower than that of CNT/epoxy nanocomposites.

Reinforcing MWCNTs to enhance viscoelastic properties of polyurethane nanocomposites by using nano DMA techniques

2020 ◽  
pp. 089270572093074 ◽  
Author(s):  
Dinesh Kumar ◽  
Navin Kumar ◽  
Prashant Jindal
Keyword(s):  
Composite Material ◽  
Storage Modulus ◽  
Viscoelastic Properties ◽  
High Strength ◽  
Mechanical Analysis ◽  
Elastic Behavior ◽  
Loading Frequency ◽  
Uniform Dispersion ◽  
Tan Δ ◽  
A Minor

Multi-walled carbon nanotubes (MWCNTs)-reinforced polyurethane (PU) composites were fabricated by using solution mixing technique followed by compression molding. Nano dynamic mechanical analysis was carried out to investigate the viscoelastic properties of PU/MWCNTs composites within a frequency range of 5–250 Hz. At higher frequencies (250 Hz), the storage modulus of PU/MWCNTs composites with 10 wt% loading of MWCNTs was enhanced by 148% in equivalence to pristine PU. An improvement of 13.3% in storage modulus was observed at a loading frequency of 250 Hz in comparison to that of a loading frequency of 75 Hz, which indicates that the effect of MWCNTs on storage modulus was more pronounced at higher frequencies. At 75 Hz, a minor composition of MWCNTs (3 wt%) was sufficient to reduce the value of tan δ from 0.20 to 0.15, indicating that the material becomes more elastic after reinforcing MWCNTs. This significant improvement in the mechanical behavior of composite material has been attributed to the uniform dispersion of MWCNTs, and their adhesion with PU molecules. Reported enhancement in the elastic behavior of PU composite will boost the applicability of PU-based composite material for the fabrication of high-strength boots, gloves, and jackets required to absorb high vibration frequencies experienced during conditions such as rock drilling.

scholarly journals Thermal Conductivity of Epoxy Resin Reinforced with Magnesium Oxide Coated Multiwalled Carbon Nanotubes

2013 ◽  
Vol 2013 ◽  
pp. 1-5 ◽  
Author(s):  
Fei-Peng Du ◽  
Hao Tang ◽  
De-Yong Huang
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanotubes ◽  
Magnesium Oxide ◽  
Multiwalled Carbon Nanotubes ◽  
Epoxy Matrix ◽  
Content Increase ◽  
Epoxy Nanocomposites ◽  
Multiwalled Carbon ◽  
Mwnt Content ◽  
Filler Content Increase

Magnesium oxide coated multiwalled carbon nanotubes (MgO@MWNT) were fabricated and dispersed into epoxy matrix. The microstructures of MgO@MWNT and epoxy/MgO@MWNT nanocomposites were characterized by TEM and SEM. Electrical resistivity and thermal conductivity of epoxy nanocomposites were investigated with high resistance meter and thermal conductivity meter, respectively. MgO@MWNT has core-shell structure with MgO as shell and nanotube as core, and the thickness of MgO shell is ca. 15 nm. MgO@MWNT has been dispersed well in the epoxy matrix. MgO@MWNT loaded epoxy nanocomposites still retain electrical insulation inspite of the filler content increase. However, thermal conductivity of epoxy was increased with the MgO@MWNT content increasing. When MgO@MWNT content reached 2.0 wt.%, thermal conductivity was increased by 89% compared to neat epoxy, higher than that of unmodified MWNT nanocomposites with the same loading content.

Effects of Different Microalloying and Controlled Cooling Technology on Microstructure and Properties of 500MPa High-Strength Rebars

2014 ◽  
Vol 633-634 ◽  
pp. 168-175
Author(s):  
Wei Chen ◽  
Jian Chun Cao ◽  
Zhe Shi ◽  
Yin Hui Yang ◽  
Yu Zhao
Keyword(s):  
Testing Machine ◽  
High Strength ◽  
Good Effect ◽  
Tensile Fracture ◽  
Controlled Cooling ◽  
Tensile Testing Machine ◽  
Impact Machine ◽  
Obvious Effect ◽  
Tensile Fracture Surface ◽  
Cooling Technology

The mechanical properties and microstructures of three different VN, Nb, V-Nb microalloyed rebars were investigated by using tensile testing machine, impact machine, metallographic microscopy, scaning electron microcopy, transmission electron microscopy and X-ray diffraction apparatus. The results showed that the microstructure of V-Nb microalloyed specimen is consisted of ferrite, pearlite and a small amount of fine bainite (6.7wt%), and obvious effect of grain refinement was obtained with more than 10 size grade of ferrite grain, showing optimal comprehensive properties. SEM micrograph of tensile fracture surface for V-Nb microalloyed 500MPa high-strength rebar is dimple and ductile, ductile-brittle transformation temperature is lower than-30°C, which has good plasticity-toughness and impact toughness at low temperature. The results of precipitates have shown that a large number of small and dispersive V(CN) and Nb (CN) precipitates with size of 5~30nm are formed, good effect of precipitation strengthening was achieved in 500MPa high-strength rebars produced by different microalloying and controlled cooling technology.

The Experimental Study on Sensitivity of Hydrogen Embrittlement of 20Cr2Ni4A High-Strength Steel Cleaned by Ultrasonic and Deruster

2011 ◽  
Vol 291-294 ◽  
pp. 1136-1140
Author(s):  
Ling Dong Meng ◽  
Qing Zhang ◽  
Zhi Jie Liang
Keyword(s):  
Experimental Study ◽  
Hydrogen Embrittlement ◽  
High Strength ◽  
Sem Analysis ◽  
Tensile Fracture ◽  
Tensile Fracture Surface ◽  
Mechanics Performance ◽  
Long Time ◽  
Short Time ◽  
Rupture Mechanism

In order to test whether there is the change of mechanics performance cleaned by ultrasonic and deruster, the experiments on mechanics performance and sensitivity of hydrogen embrittlement have been conducted. During the experiments, 20Cr2Ni4A steel are selected as the materials, which endure the relatively great concussion load in the bad condition, and the gaps’ long-time permanence experiments and short-time tension and concussion experiments have been done. Through the compare of mechanics performances and the SEM analysis of tensile fracture surface of the samples, it can be proved that the mechanics performances and rupture mechanism are the same, no matter whether the materials are cleaned by ultrasonic and deruster or not. These indicate that it doesn’t bring the change of mechanics performances and hydrogen embrittlement to clean the materialss by ultrasonic and deruster.

Effect of functionalization of multi-walled carbon nanotube on mechanical and viscoelastic properties of polysulfide-modified epoxy nanocomposites

2016 ◽  
Vol 29 (2) ◽  
pp. 151-160 ◽  
Author(s):  
Yeping Wu ◽  
Zhongyun Gu ◽  
Maobin Chen ◽  
Chunhua Zhu ◽  
Hong Liao
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanotube ◽  
Photoelectron Spectroscopy ◽  
Epoxy Matrix ◽  
Viscoelastic Properties ◽  
Mechanical Analysis ◽  
Epoxy Nanocomposites ◽  
X Ray ◽  
Multi Walled Carbon Nanotube ◽  
Modified Epoxy

In order to obtain epoxy compounds with excellent mechanical properties without compromising other desired properties, pristine- or carboxyl-functionalized multi-walled carbon nanotube (p-MWCNT or f-MWCNT) along with polysulfide were incorporated into an amine-cured epoxy resin. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analyses proved the existence of carboxyl groups on the surface of f-MWCNT. Adding 0.1 wt% f-MWCNT significantly improved the tensile strength and impact strength of the epoxy nanocomposites by 104% and 47%, respectively. However, adding p-MWCNT had little effect on the mechanical properties of the nanocomposites. The glass transition temperature of the f-MWCNT/epoxy nanocomposites were also much higher than neat epoxy matrix and p-MWCNT/epoxy nanocomposites. The fracture surface morphology and dynamic mechanical analysis results indicated that the interfacial interactions between f-MWCNT and the epoxy matrix were much stronger than that of p-MWCNT, which ensured the much-improved mechanical properties.

Mechanical and viscoelastic properties of epoxy nanocomposites reinforced with carbon nanotubes, nanoclay, and binary nanoparticles

2017 ◽  
Vol 36 (9) ◽  
pp. 667-684 ◽  
Author(s):  
Mahesh Hosur ◽  
Tanjheel H Mahdi ◽  
Mohammad E Islam ◽  
S Jeelani
Keyword(s):  
Carbon Nanotubes ◽  
Epoxy Resin ◽  
Viscoelastic Properties ◽  
Flexural Modulus ◽  
Flexural Test ◽  
Epoxy Nanocomposites ◽  
Multiwalled Carbon ◽  
Epoxy Resin System ◽  
Functionalized Multiwalled Carbon Nanotubes ◽  
Binary Nanoparticles

Mechanical and viscoelastic properties of polymer nanocomposites reinforced with carboxyl functionalized multiwalled carbon nanotubes (COOH-MWCNT), montmorillonite nanoclays (MMT), and MWCNT/MMT binary nanoparticle were investigated. In this study, 0.3 wt% of COOH-MWCNT, 2 wt% of MMT, and 0.1 wt% COOH-MWCNT/2 wt% MMT binary nanoparticles by weight of epoxy were incorporated to modify SC-15 epoxy resin system. Nanocomposites were subjected to flexural test, dynamic mechanical, and thermomechanical analyses. Morphological study was conducted with microscopy. Addition of each of the nanoparticles in epoxy showed significant improvement in the mechanical and viscoelastic properties compared to those of the control ones. However, best results were obtained by addition of 0.1% MWCNT/2% MMT binary nanoparticles in epoxy. Nanocomposites modified with binary nanoparticles exhibited about 20% increase in storage modulus as well as 25℃ increase in the glass transition temperature. Flexural modulus for binary nanoparticle modified composites depicted about 30% improvement compared to the control ones. Thus, improvement of mechanical and viscoelastic properties was achieved by incorporating binary nanoparticles to epoxy nanocomposites. The increase in properties was attributed to the synergistic effect of MWCNTs and nanoclay in chemically interacting with each other and epoxy resin as well as in arresting and delaying the crack growth, once initiated.

scholarly journals Microstructural Characterization and Mechanical Property of Al-Li Plate Produced by Centrifugal Casting Method

Metals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 966
Author(s):  
Qingle Tian ◽  
Kai Deng ◽  
Zhishuai Xu ◽  
Ke Han ◽  
Hongxing Zheng
Keyword(s):  
Centrifugal Casting ◽  
High Strength ◽  
Microstructural Characterization ◽  
Fracture Morphology ◽  
Total Elongation ◽  
Mechanical Anisotropy ◽  
Tensile Fracture ◽  
Casting Method ◽  
Scanning Calorimetry ◽  
Strengthening Phases

Using a centrifugal casting method, along with deformation and aging, we produced a high-strength, low-anisotropy Al-Li plate. The electron probe microanalysis, transmission electron microscope, differential scanning calorimetry, and X-ray diffraction were used to clarify the evolution of strengthening phases. Experimental results showed that centrifugal-cast Al-Li plate consisted of intragrain δ′—(Al,Cu)3Li precipitate and interdendritic θ′—Al2Cu particles. After cold-rolling to a reduction ratio of 60% and annealing at 800 K for 90 min, both primary θ′ and δ′ were dissolved in solid solution. Aging at 438 K for 60 h led to the formation of two kinds of precipitates (needle-like T1—Al2CuLi and spherical δ′ in two sizes), which acted as the main strengthening phases. The average values of ultimate tensile strength and yield strength for the anneal-aged plate reached 496 MPa and 408 MPa, with a total elongation of 3.9%. The anneal-aged plate showed mechanical anisotropy of less than 5%. The tensile fracture morphology indicated a typical intergranular fracture mode.

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