Dispersion Of MWCNTs Research Articles

Detailed study on interfacial interactions in epoxy composites cured with 1-buthylimidazole containing functionalized carbon nanotubes

This work provides a detailed information on the preparation process and characterization of functionalized multiwalled carbon nanotubes/Epidian 6 nanocomposites using ARES rheometer, TGA, and DSC measurements, with the imidazole derivative as a curing agent. Scanning electron microscopy of the fracture surfaces of the composites with a total nanofiller concentration below 0.5 wt.% reveals a uniform dispersion of MWCNT with only some minor agglomerates. At the same time, the TEM analysis of the composite with a total concentration of MWCNT–COOH higher than 0.5 wt.% confirmed the presence of carbon nanotube aggregates along with a large number of places without any presence of nanoparticles in the whole volume of the epoxy matrix. Mechanical tests (bending as well as dynamic mechanical analysis) show that compared with the neat epoxy resin, the bending strength of the composite was improved by about 30 and 21% after incorporating as little as only 0.1 and 0.2 wt.% MWCNT–COOH, respectively. The work presented hereby is a continuation of a previous study on epoxy-based nanocomposites with different types of multiwalled carbon nanotubes and it is a part of a wider project on precise charting of the influence of carbon nanotubes (particularly multiwalled carbon nanotubes) in the system of epoxy resin with 1-buthylimidazole, as a curing agent.

Effect of convergent–divergent flow on thermal and crystallization properties of PP/MWCNTs nanocomposites

ABSTRACTA melt‐mixing process based on convergent–divergent flow has been used to prepare PP/MWCNT composites with a self‐built convergent–divergent die (C‐D die) composed of different numbers of convergent plates. Dynamic extensional deformation was generated in the C‐D die, which improved the mixing effect and mixing efficiency of the composites during extrusion. The C‐D die acted as a mixer for composites when mounted onto a capillary rheometer. The residence time of PP/MWCNTs melt in the extensional flow field is adjusted by changing the numbers of convergent plates and the velocity of the ram. The intensity of extensional flow field is controlled by the structure of the convergent plate and the ram velocity. Influences of convergent–divergent flow on PP/MWCNTs composites were characterized in terms of transmission electron microscopy (TEM), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). TEM results showed that MWCNTs disperse more homogeneously with the increase of convergent plates. DSC showed that the crystallinity of PP/MWCNTs composites increased and the crystallization temperature shifted to higher temperature with the increase of the numbers of the convergent plates. TGA showed that the thermal stability of composites improved remarkably. The decomposition temperature increases from 381 to 408.2°C when the numbers of convergent plates increased from 2 to 8. In addition, the increase of ram velocity also has the same influences on the dispersion of MWCNTs in the resin and the properties of PP/MWCNTs nanocomposites. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42330.

Si/Mo/MWCNT Nanocomposites for Lithium Ion Battery Applications

In this study, silicon/multi-wall carbon nanotube (Si/MWCNT) and silicon/molybdenum/multi-wall carbon nanotube (Si/Mo/MWCNT) composites were produced by high speed planetary ball milling. Produced Si/MWCNT composite containing 50 wt.% Si and 50 wt.% MWCNT and dispersingdi erent amount of molybdenum nanopowders (1 wt.%, 3 wt.% and 5 wt.%) Si/Mo/MWCNT composites were produced by high speed planetary ball milling. Surface morphology of produced composite electrodes was characterized using scanning electron microscopy (SEM) and EDS dot-map analyze was performed to investigate dispersion of MWCNT and molybdenum powders in the composite structure. X-ray di raction (XRD) technique was carried out to investigate structure of produced Si/Mo/MWCNT composites. Electrochemical performance of the electrodes were tested between 50 mV and 1.5 V in CR2016 test cell.

Characterization of alkali activated geopolymer mortar doped with MWCNT

【This paper aimed to investigate the effect of MWCNTs on properties of slag Geopolymeric mortar. Geopolymeric matrices containing different MWCNTs concentrations (0.0, 0.1, 0.2, 0.3 and 0.4 % by weight of the used binder) were synthesized. The Geopolymer mortar composed of aluminosilicate slag to sand (1:2), while the alumino silicate source binder composed of 50% air cooled slag and 50%water cooled slag both passing a sieve of $90{\mu}m$ , while the sand passing a sieve of 1 ml. The materials prepared at water/binder ratios in a range of 0.34-0.39% depending on the added MWCNT, whereas the Gelenium Ace-30 superplasticizer used in the ratio of 1.4-2.2% from the total dry weight for better dispersion of MWCNT under sonication for 15 min. Alkaline activation of the Geopolymer mortar was carried by using of 6% NaOH. Curing was performed under temperature of $40^{\circ}C$ and 100% R.H. Results showed that the addition of MWCNTs enhanced the resulting amorphous geopolymer structure with marked decrease in the drying shrinkage as well as water absorption specially when using 0.1% MWCNT, while further increase in MWCNTs results in agglomeration in MWCNT within the matrix and so hinder the propagation of Geopolymerization reaction and negatively affect the formed geopolymer structure.】

Characterization of polyamide 6/carbon nanotube composites prepared by melt mixing-effect of matrix molecular weight and structure

Effects of molecular weight and structure of polyamide 6 (PA6) on morphology and properties of PA6/MWCNT prepared by melt mixing were investigated. Microscopic analysis showed fine dispersion of MWCNT within low viscosity PA6s due to domination of melt infiltration into MWCNT agglomerate at low viscosity matrices with linear structure. Rheological data indicated good interfacial interaction with no percolation of MWCNT up to 2 wt% loading. DSC thermograms showed nucleating role of MWCNT on crystallization of PA6s with marginal effect on crystallinity. Experimental data supported with micromechanical model showed limited improvement on mechanical properties, but it was closely consistent with degree of dispersion of MWCNT.

Mechanical and electrical properties of chemically modified MWCNTs/3Y-TZP composites

In the present work, homogeneous dispersion of MWCNTs in ZrO2 matrix was achieved by the chemical modification of MWCNTs and the formation of noncovalent attachment between carboxyl acid (–COOH) groups on MWCNTs and ZrO2 particles to obtain better compatibility of MWCNTs in ZrO2 matrix. 3Y-TZP/4wt% MWCNTs composite exhibited the best indentation toughness of 6.24MPam1/2 increasing 31% over monolithic ZrO2. Nanoindentation measurements showed that Young׳s modulus, hardness and contact-damage-resistance decreased with increasing the MWCNTs content. Moreover, the electrical conductivity slightly increased for MWCNTs weight fraction below 1wt% and displayed a dramatic increment with a maximum corresponding to MWCNTs weight fraction of 4wt%, which can be described by the percolation theory.

그래핀 옥사이드가 탄소나노튜브기반 바이오센서 전극의 포도당 산화효소 담지능및 민감도에 미치는 영향

To improve both the GOD immobilization capability and sensitivity of MWCNTs-based biosensor electrode, the electrode was prepared by adding different quantities of GO. The addition of GO increased hydrophilicity and the surface free energy of electrodes for glucose sensing as well as the dispersion of MWCNTs. In addition, the GOD immobilization capability was enhanced and the sensitivity was improved up to 121 µA mM -1 even though having a high Km value (0.105) when adding 0.05 g GO to 0.05 g MWCNTs. These experimental results were attributed to the fact that the improvement in dispersion stability for MWCNTs, hydrophilicity, and surface free energy of electrode surface due to the addition of GO affected GOD immobilization capability.

The Dispersion of MWCNTS in Acetone Solution of SAN

MWCNTs were dispersed in acetone solution of styrene-acrylonitrile copolymer (SAN). Four factors which had effect on the average particle size, including the ratio of MWCNTs to SAN, the mass percent of MWCNTs, the ultrasonic power and the ultrasonic time, were studied. The optimal dispersion conditions of MWCNTs in acetone solution of SAN were the ratio of MWCNTs to SAN 1:3, the mass percent of MWCNTs 0.25%, the ultrasonic power 100%, and the ultrasonic time 30 min.

Synthesis of New PI/MWCNT Containing Sulfone Groups via In Situ Polymerization: Study on Thermal, Electrical, and Optical Properties

New series of polyimide (PI) nanocomposites reinforced with three different amounts of multiwalled carbon nanotubes (MWCNT; 0.5, 1, and 3 wt%) were prepared by casting, evaporation and thermal imidization. Homogeneous dispersion of MWCNT in PI matrix was investigated by transmission electron microscopy. The effects of MWCNT on the thermal properties of the PI were investigated by thermogravimetric analysis. The results showed that the thermal stability of the nanocomposites enhanced with the increasing MWCNTs content. The resultant PI/MWCNT nanocomposites were electrically conductive with significant conductivity enhancement at 3 wt% MWCNT, which is favorable for many practical uses.

An extremely uniform dispersion of MWCNTs in olefin block copolymers significantly enhances electrical and mechanical performances

A new guidance for the development of conductive elastomers with improved comprehensive performance by considering chain architecture is provided.

Supramolecular modification of multi-walled carbon nanotubes with β-cyclodextrin for better dispersibility

A novel hybrid material based on multi-walled carbon nanotubes was synthesized using organic synthesis, and the structures of multi-walled carbon nanotube derivatives were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, 1H NMR spectroscopy, transmission electron microscopy, and scanning electron microscope. The analytical results indicated that β-cyclodextrin (β-CD) was anchored to the surface of Multi-walled carbon nanotubes (MWCNTs, OD: 10–20 nm, length: 10–30 μm) and dispersion experiments exhibited that the introduction of β-CD onto the MWCNTs would dramatically enhance the dispersion of MWCNTs in both ethanol and water media; the suspensions were found to be very stable for 2 months, and the results of this technique confirmed the experimental results. This novel technique would provide a new, simple, and facile route to prepare the modified nanomaterials based on silane-coupling agent and β-CD, and the obtained modified nanomaterials have great potential practical significance and theoretical value to develop the novel organic–inorganic hybrid material, which was very useful for water treatment and biological medicine.

Multilayer mixed matrix membranes containing modified-MWCNTs for dehydration of alcohol by pervaporation process

In this work, multilayer mixed matrix membranes containing carbon nanotubes (CNTs), poly(vinyl alcohol) (PVA), polyethersulfone (PES) and polyester as inorganic filler and selective top, intermediate and support layers, respectively, were prepared for dehydration of ethanol/water mixtures by the pervaporation process. For this purpose, the MWCNTs were synthesized by the thermal-chemical vapor deposition (T-CVD) technique and then the CNTs were modified by incorporating carboxyl functional groups and synthesizing titanium oxide (TiO2) nanocrystals on them. The results indicated that the MWCNTs with high purity were prepared and carboxyl functional groups were formed on the CNTs. The membranes containing modified MWCNTs had lower swelling degree and higher crosslinking density which resulted in lower total permeation flux in comparison to the neat membrane and the membranes containing pure MWCNTs. Furthermore, the hydrophilicity, surface roughness and crosslinking of the membranes were improved by increasing the concentration of modified CNTs. All mixed matrix membranes had lower total flux than the neat membranes due to an increase of the membrane top layer resistance by incorporating the MWCNT filler. Finally, it was observed that the modification of CNTs led to better dispersion of MWCNTs into the polymeric matrix and improved the separation performance of the multilayer mixed matrix membranes.

Dispersability of multiwalled carbon nanotubes in polycarbonate-chloroform solutions

The dispersion of commercial multiwalled carbon nanotubes (MWCNTs, Nanocyl™ NC7000) in chloroform and in polycarbonate (PC)-chloroform solutions was investigated by variation of the polymer concentration, MWCNT amount and sonication time and compared with PC/MWCNT composites, which were processed by melt mixing, subsequently dissolved in chloroform and dispersed via sonication under the same conditions. The sedimentation behaviour was characterised under centrifugal forces using a LUMiSizer® separation analyser. The space and time resolved extinction profiles as a measure of the stability of the dispersion and the particle size distribution were evaluated. Sonication up to 5 min gradually increases the amount of dispersed particles in the solutions. A significant improvement of the MWCNT dispersion in chloroform was achieved by the addition of PC indicating the mechanism of polymer chain wrapping around the MWCNTs. In dispersions of melt mixed PC/MWCNT composites the dispersion of MWCNTs is significantly enhanced already at a low sonication time of only 0.5 min due to very efficient polymer wrapping during the melt mixing process. However, the best dispersion quality does not lead to the highest electrical conductivity of thin composite films made of these PC/MWCNT dispersions.

Electrochemical sensor for chloramphenicol based on novel multiwalled carbon nanotubes@molecularly imprinted polymer

Herein, we present a novel electrochemical sensor for the determination of chloramphenicol (CAP), which is based on multiwalled carbon nanotubes@molecularly imprinted polymer (MWCNTs@MIP), mesoporous carbon (CKM-3) and three-dimensional porous graphene (P-r-GO). Firstly, 3-hexadecyl-1-vinylimidazolium chloride (C16VimCl) was synthetized by using 1-vinylimidazole and 1-chlorohexadecane as precursors. Then, C16VImCl was used to improve the dispersion of MWCNT and as monomer to prepare MIP on MWCNT surface to obtain MWCNTs@MIP. After that, the obtained MWCNTs@MIP was coated on the CKM-3 and P-r-GO modified glassy carbon electrode to construct an electrochemical sensor for the determination of CAP. The parameters concerning this assay strategy were carefully considered. Under the optimal conditions, the electrochemical sensor offered an excellent response for CAP. The linear response ranges were 5.0×10−9–5×10−7molL−1 and 5.0×10−7–4.0×10−6, respectively, and the detection limit was 1.0×10−10molL−1. The electrochemical sensor was applied to determine CAP in real samples with satisfactory results.

Dispersion and Degradation of Polycarbonate/MWCNT Nanocomposites with Melt Extrusion

Polycarbonate/Multi-wall Carbon Nanotubes (PC/MWCNT) nanocomposites with 0.55% and 0.77% of MWCNT were prepared by twin-screw compounding extruder. The morphology and dispersion were characterized by SEM. The Raman analysis confirmed the good interaction between carbon nanotubes (CNTs) and Polycarbonate (PC). The TGA result showed that the PC/MWCNT nanocomposites degraded in two time extrusion (TTE) as compared to one time extrusion (OTE), which was attributed to the temperature effect. Inspite of degradation, TTE nanocomposite showed good dispersion of MWCNT in PC.

Hybrid S-valine functionalized multi-walled carbon nanotubes/poly(amid-imide) nanocomposites containing trimellitimidobenzene and 4-hydroxyphenyl benzamide moieties: preparation, processing, and thermal properties

In this paper, amino acid functionalized multi-walled carbon nanotubes (f-MWCNTs)/poly(amide-imide) (PAI) nanocomposites (NCs) were prepared by a solution mixing method. First, 4,4′-methylenebis(3-chloro-2,6-diethyl trimellitimidobenzene) reacted with 3,5-diamino-N-(4-hydroxyphenyl)benzamide in tetra-n-butylammonium bromide as a green medium and a safe methodology (toxic and volatile organic solvents were eliminated) to produce a nanostructured PAI in high yield. MWCNTs were chemically modified with S-valine using microwave irradiation in order to obtain a homogeneous dispersion of MWCNTs in the PAI matrix. The resulting NCs were also characterized by FT-IR, powder X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and thermogravimetric analysis. The TEM and FE-SEM images confirmed good dispersion of f-MWCNTs in the polymer matrix. The results of TGA analysis suggest that a good thermal stability occurs especially with low filler amounts (5 wt%) of f-MWCNT.

Effect of non-ionic surfactants on thermomechanical properties of epoxy/multiwall carbon nanotubes composites

Epoxy/multiwall carbon nanotubes (MWCNTs) composites were investigated using three different non-ionic surfactants (BYK-110, Tween-80 and Nonidet-P40) separately as a modifier. The role of surfactants in dispersion of MWCNTs in the epoxy matrix was studied. Among three surfactants used, performance of Nonidet-P40 was found to be the best in improving the thermomechanical properties of the epoxy resin and achieving good dispersion of MWCNTs. The good dispersion of Nonidet-P40 modified MWCNT in the epoxy matrix is a result of the π–π interaction between π electrons of the Nonidet-P40 and π electron clouds of MWCNTs as well as H-bonding interaction between of Nonidet-P40 and the epoxy matrix. This type of interaction does not disturb the π electron clouds of MWCNTs as opposed to chemical functionalization strategy.

Modification and dispersion of multi-walled carbon nanotubes in water

In the present work, the decorated purified raw multi-walled carbon nanotubes (R-MWCNTs) were obtained by chemical modification (CM) by treatment with concentrated sulfuric acid and concentrated nitric acid mixture with a certain volume ratio of 1: 3. The R-MWCNTs and CM-MWCNTs samples were investigated by X-ray Diffraction (XRD) analysis and Fourier transform infrared spectroscopy (FT-IR). The prepared MWCNTs were homogeneously dispersed in water using a commercial surfactant (Polyvinyl pyrrolidone, (PVP)) and ultra-sonication. The dispersion of MWCNTs was obtained by UV-Vis analysis. The results show that chemical modification purified MWCNTs and more effective functional groups were attached on the surface of MWCNTs. Meanwhile, R-MWCNTs and CM-MWCNTs were uniformly distributed in aqueous PVP solution and the dispersion of CM-MWCNTs in water was better.

Impact of foaming on the broadband dielectric properties of multi-walled carbon nanotube/polystyrene composites

This study investigated the impact of foaming on the broadband dielectric properties of multi-walled carbon nanotube/polystyrene (MWCNT/PS) nanocomposites. Different carbon nanotube concentrations were prepared by blending of a 20 wt.% MWCNT/PS masterbatch and pure PS using a twin-screw extruder. A chemical blowing agent was used to foam the nanocomposites in a micro injection molding machine. Compression molding was applied to fabricate unfoamed nanocomposites for comparison purposes. Comparing the dielectric properties of unfoamed and foamed nanocomposites showed that foaming increased the percolation threshold, reduced DC and AC conductivities, widened the insulator–conductor transition window, and reduced the dissipation factor of the MWCNT/PS composites. These were attributed to deteriorated conductive network and inferior dispersion and distribution of MWCNTs coming from the presence of foam cells in the nanocomposites. The obtained results propose foaming as a promising technique to improve the dielectric properties of MWCNT/polymer composites.

Origin of mechanical modifications in poly (ether ether ketone)/carbon nanotube composite

Variations in the hardness of a poly (ether ether ketone) beam electrically modified with multi-walled carbon nanotubes (MWCNT, 0.5%-3%) are investigated. It is shown that both rupture and hardness variations correlate with the changes in carbon nanotube concentration when using micro indentation and extended Raman imaging. Statistical analysis of the relative spectral intensities in the Raman image is used to estimate local tube concentration and polymer crystallinity. We show that the histogram of the Raman D band across the image provides information about the amount of MWCNTs and the dispersion of MWCNTs in the composite. We speculate that we have observed a local modification of the ordering between pure and modified polymer. This is partially supported by small angle neutron scattering measurements, which indicate that the agglomeration state of the MWCNTs is the same at the concentrations studied.