Mutliwalled Carbon Nanotubes Research Articles

Role of polystyrene/multiwall carbon nanotubes concentrations on the morphological properties of prepared nanofibers nanocomposites

The electrospinning technique was used to prepare nanofibers samples consisting of three groups, each group has a different polystyrene concentration (12, 14, 16 wt.%). Multiwalled carbon nanotubes were added to each group with four ratios to yield four samples comprising (polystyrene/MWCNT) constituents. The UV-Visible test was carried out to know how uniformly nanofibers and Mutli-walled carbon nanotubes were distributed in the polymeric nanofibers and their effect on the final nanofiber’s properties through the absorption peaks. The morphological test used “Field Emission Scanning Electron Microscope”. The results showed that; MWCNTS has a dominant effect on prepared nanofibers in the (12 wt.% Polystyrene) group, and both (PS, MWCNT) have a shared effect, highest steady absorption curves, and uniformly scattered radiation at (14 wt.% PS) group, and random results at (16 wt.% PS) group. From FESEM results we notice that increasing polymer concentration causes an increase in the nanofiber’s diameter and beads formation chance increases at (12,16 wt.% PS) groups. In the group of (14 wt.% Polystyrene), it produces nanofibers with free beads and uniform distribution, the addition of MWCNT lowers the diameter of nanofibers much more and enhances the orientation, and improves their UV absorption, strength, and mechanical properties.

Water quality parameters as indicators to study the interactions of nanoparticles in an aqueous environment

The continuous increasing usage of nanoparticles (NPs) in industrial and household applications and release of those materials into the aquatic environment may pose risk to different ecosystems affecting its quality. Based on the literature, it is observed that there is lack of availability of direct data relevant to the interactions of NPs in aquatic or soil environment. In this context, a study was envisaged to investigate the transport potential and behavioural aspects of NPs (metal-oxide NPs (Fe2O3, Al2O3) and Mutliwalled Carbon Nanotubes (MWCNTs)) in the presence of inorganic colloids (nanoclay (Montmorillonite-k10)) and organic pollutant (Red-CLB dye) in the aquatic environment. Since it is very intricate to comprehend the kind of interactions between NPs and determine the change in the concentration of NPs during interactions in the aquatic environment, the measured variation in the water quality parameters like hardness, chloride and total dissolved solids (TDS) were used as indicators. The intrinsic properties of NPs like particle size, morphology, functional groups and crystal structure during interactions of NPs were studied using XRD (X-Ray Diffraction), SEM (Scanning Electron Microscope), FTIR (Fourier Transform Infra-Red) and EDX (Energy Dispersive X-ray spectroscopy).The observed types of interactions of NPs in water (adsorption, aggregation, deposition, ion exchange, isomorphic substitution) during the conducted experimental investigations at different pH and ionic concentration might be helpful for further research in this direction. The observed results may be useful for the decision makers on the type of treatment to be given before releasing NPs into the aqueous environment.

Carbon Nanotube Embedded Smart Polymer Composite for Strain and Piezo-Resistive Data Transducer Application

In this paper we report the application of carbon nanotube decorated polymer composite as a strain sensor. Mutli-walled carbon nanotubes (MWCNTs) were synthesized by zeolite assisted chemical vapour deposition (CVD) and blended with polyvinylchloride (PVC). Field Emission Scanning Electron Microscopy (FESEM) has been used to characterize the morphology, FTIR spectroscopy and UV–Vis spectroscopy were used to characterize the structure of the PVC/MWCNTs composite. The piezo-resistive responses of the PVC/MWCNTs composite with different fabrication methods has been optimized. The studies on applying dynamical loads on the PVC/MWCNTs composite demonstrate that the composite functions as an excellent strain and stress sensor.

PP/MWCNTs composites: Effects of length of MWCNTs on isothermal crystallization behaviors, crystalline structure, and thermal stability

This study adopts the melt compounding method to prepare /mutli-walled carbon nanotubes composites. The effects of different lengths of the mutli-walled carbon nanotubes on the isothermal crystallization behaviors, crystalline structure, and thermal stability of the polypropylene/mutli-walled carbon nanotubes composites are examined. The PLM results show that the combination of mutli-walled carbon nanotubes prevents the growth of polypropylene spherulites, and thus results in a small size of spherulites. The differential scanning calorimetry results show that the short (S-) or long (L-) mutli-walled carbon nanotubes can function as the nucleating agent of polypropylene, which accelerates the crystallization rate of polypropylene. Avrami theory analyses indicate that the addition of short-mutli-walled carbon nanotubes particularly provides polypropylene/mutli-walled carbon nanotubes composites with a high crystallization rate. The X-ray diffraction results show that the combination of mutli-walled carbon nanotubes does not pertain to the crystal structure. The TGA test results show that long-mutli-walled carbon nanotubes outperform short -mutli-walled carbon nanotubes in improving the thermal stability of polypropylene, and both can significantly improve it.

Lubricant Enhancement via Hydrodynamic and Acoustic Cavitation

Lubricant plays a vital role in reducing wear, friction and energy consumption in any machinery. It is mainly used in automotive, industrial, processing, and marine. Various types of lubricant were developed from time to time to meet with the market requirement. However, lubricant performance demanded by market changes as the application varies. For instance, lubricant with high thermal stability is required in drilling, which is High Temperature High Pressure (HPHT) condition. Recent studies have revealed that by adding an optimum concentration of nanoparticles into lubricant, the tribological performance of the lubricant can be improved significantly. Viscosity of lubricant is vital in terms of forming lubricating film and reduces friction. In this study, mutliwalled carbon nanotubes were added to lubricants through hydrodynamic and acoustic cavitation. The results indicated that addition of multiwalled CNT definitely improve nanofluids’ viscosity. Besides, comparison between methods of preparation showed that hydrodynamic cavitation alone yield best suspension with highest viscosity in both 25 ppm and 100 ppm cases.

Effect of oxide nanoparticles on structural properties of multiwalled carbon nanotubes

A simple chemical precipitation route is reported to partially decorate mutliwalled carbon nanotubes (MWCNTs) with oxide nanoparticles in the present study. X-ray diffraction (XRD), Raman spectroscopy and Scanning electron microscopy (SEM) are used to investigate the structural properties of MWCNTs composite with nickel, cuprous, zinc and tin oxides nanoparticles. Raman analysis confirms that, ZnO nanoparticles attached nanotubes show more ordering of graphene layers as compared to the others because of uniform dispersion of nanoparticles. It is investigated that, adopted route proved helpful to improve the structural properties of the nanotubes.

Effect of highly dispersed sputtered silver nanoparticles on structural properties of multiwalled carbon nanotubes

A simple method to decorate mutliwalled carbon nanotubes (MWCNTs) with silver nanoparticles (Ag NPs) to enhance the structural properties is reported in the present study. The Ag NPs of average size 9nm were deposited uniformly on MWCNTs network by RF sputtering technique. X-ray diffraction (XRD), Raman spectroscopy and Scanning electron microscopy (SEM) are used to compare the structural properties of Ag NPs sputtered nanotubes with those containing functionalized tubes. In addition, effect of these Ag NPs on the surface of nanotubes and optimization of the experimental parameter for uniform deposition of Ag NPs are also discussed.

고분자 복합재의 물리화학적 및 전자파차폐 특성에 미치는 탄소나노튜브의 불소화 영향

탄소나노튜브의 불순물을 제거하고 에폭시 수지와의 계면접착력 향상과 에폭시 내 탄소나노튜브의 분산성 증가를 위하여 불산(hydrofluoric acid)으로 그 표면을 개질하였다. 표면 처리된 탄소나노튜브의 결정성은 광전자 분광기(X-ray photoelectron spectroscopy)와 라만 분광기(Raman spectroscopy)를 통해 분석하였고, 인장시험으로 기계적 강도 분석을 실시하였다. 표면 처리된 탄소나노튜브/에폭시 복합재의 인장강도는 미처리 탄소나노튜브/에폭시 복합재와 비교하여 최대 약 33% 향상됨을 확인할 수 있었고, 탄소나노튜브/에폭시 복합재의 전자파차폐 특성은 탄소나노튜브의 불산처리 농도에 따라 증가하는 경향을 보였고 25%의 농도로 처리되었을 때, 최대 전자파차폐 특성을 보였다. 그러나 기계적 특성 및 전자파차폐 특성은 50% 이상의 불산 농도로 처리된 탄소나노튜브/에폭시 복합재에서 오히려 감소하였으며 이는 높은 농도의 불산으로 인하여 탄소나노튜브의 표면 결정성 감소 및 고유 특성에 영향을 미친 것으로 파악된다. 고분자 복합재의 기계적, 전기적 특성 향상은 불산 처리로 인한 탄소나노튜브의 결정성 향상과 에폭시 수지 내에 분산성의 증가에 기인하였다. Mutli-walled carbon nanotubes (MWCNTs) were surface-modified by a hydrofluoric acid solution to remove impurities and improve interfacial bonding and dispersion of nanotubes in an epoxy matrix. The crystallinity on the surface of treated MWCNTs was investigated by X-ray photoelectron spectroscopy and Raman spectroscopy. The mechanical properties were characterized by tensile test, and the enhancement of mechanical properties of the modified MWCNTs/epoxy composites was indicated by a 33% increase in tensile strength. The electromagnetic interference shielding effectiveness (EMI-SE) of modified MWCNTs/epoxy composites was improved with an increase in concentration of hydrofluoric solution, and EMI-SE showed the maximum increase with 25% HF. However, mechanical and EMI-SE properties didn't show further increase with over 50% HF concentration because the properties of MWCNTs were influenced by degradation of crystallinity and intrinsic properties of MWCNTs. The mechanical and electrical property enhancements of the polymer composites are attributed to the modification of MWCNTs which improve crystallinity of MWCNTs and dispersion in the epoxy resin.

Mechanical Properties of Individual Composite Poly(methyl-methacrylate) -Multiwalled Carbon Nanotubes Nanofibers

Multiwalled carbon nanotubes with their superb mechanical properties are an unique filler material for polymer composites. Here, we present an investigation of mechanical properties of electrospun Poly-(methyl-methacrylate) multiwalled carbon nanotubes composite nanofibers. The method of electrospinning was used to fabricate suspended individual Poly-(methyl-methacrylate) multiwalled carbon nanotubes nanofibers. In order to reinforce the nanofibers, different high concentration of multiwalled carbon nanotubes were used. Transmission electron microscopy measurements reveal a successful filling of the nanofibers. The different types of nanofibers were deposited at SiO2 substrates. Which were previously etched, to create trenches for bend tests. Followed by fixing the nanofiber with a focus ion beam platinum deposition at the trench edges. An atomic force microscopy was used to perform the mechanical nanofiber bending tests over trenches. The results were compared with pristine Poly-(methyl- methacrylate) nanofibers to nanofibers with 15 weight% and 20 weight% multiwalled carbon nanotubes composite fibers. We observed that pristine nanofibers have Young's modulus of 136 MPa, while for composite nanofibers with 15 weight% have 2.65 GPa and with 20 weight% have 6.06 GPa (at room temperature and air ambiance). This corresponds to an increase of Young's modulus of 19 fold between the pristine nanofibers and the 15 weight% of mutliwalled carbon nanotubes filled nanofibers. Therefore the increase of the Young's modulus compared between the pristine and the 20 weight% MWCNT filled nanofibers corresponds to 45 fold.

Thermal and mechanical properties of carbon nanotube/epoxy nanocomposites reinforced with pristine and functionalized multiwalled carbon nanotubes

In this study, the effects of functionalization and weight fraction of mutliwalled carbon nanotubes (CNTs) were investigated on mechanical and thermomechanical properties of CNT/Epoxy composite. Epoxy resin was used as matrix material with pristine‐, COOH‐, and NH2‐functionalized CNTs as reinforcements in weight fractions of 0.1, 0.5, and 1.0%. Varying (increasing) the weight fraction and changing type (pristine or functionalized) of CNTs caused increment in Young's modulus and tensile strength as observed during mechanical tests. CNT reinforcement improved thermal stability of the nanocomposites as observed by thermogravimetric analysis. Thermomechanical analysis showed a slight reduction in free volume of the polymer, that is a drop in coefficient of thermal expansion, prior to glass transition temperature (Tg) beside a slight increase in Tg value. Dynamic mechanical analysis indicated an increase in storage modulus and Tg owing to the strength addition of CNT to the matrix alongside the hardener. Scanning electron microscopy analysis of the fractured surface(s) revealed that CNTs were well dispersed with no agglomeration and resulted in reinforcing the matrix. POLYM. COMPOS., 36:1891–1898, 2015. © 2014 Society of Plastics Engineers

Graphene-Based Chemical Sensors.

Pioneering research in 2004 by Geim and Novoselov (2010 Nobel Prize winners in Physics) of the University of Manchester led to the isolation of a monolayer graphene sheet. Graphene is a single-atom-thick sheet of sp(2) hybridized carbon atoms that are packed in a hexagonal honeycomb crystalline structure. Graphene is the fundamental building block of all sp(2) carbon materials including single-walled carbon nanotubes, mutliwalled carbon nanotubes, and graphite and is therefore interesting from the fundamental standpoint as well as for practical applications. One of the most promising applications of graphene that has emerged so far is its utilization as an ultrasensitive chemical or gas sensor. In this article, we review some of the significant work performed with graphene and its derivatives for gas detection and provide a perspective on the challenges that need to be overcome to enable commercially viable graphene chemical sensor technologies.

A Novel Amperometric Immunosensor for Detection of Alpha-Fetoprotein Based on Magnetic and Electroactive Nanoprobes

A novel three-dimensional, magnetic and electroactive nanoprobes were constructed for the first time. Using hemin (TPP) as electron mediator, mutli-walled carbon nanotubes with carboxyl groups (MCNTs) as supporter, a novel (MCNTs-TPP-Fe3O4)magnetic nanocomposites were first prepared. Then using alpha-fetoprotein (AFP) as model system, gold nanoparticles (Au NPs) as immobilizing matrix, the AFP/anti-AFP/Au NPs/ MCNTs-TPP-Fe3O4nanoprobes were prepared and then dropped on the surface of screen-printed working electrode (SPCE) to construct a new amperometric immunosensors for detecting biomakers. The microstructure of different nanoparticles were observed by transmission electron microscopy (TEM) andX-ray fluorescence spectrometery (XRFS). Under optimal experimental conditions, the logarithm of response signal was proportional to the logarithm of AFP concentration from 0.1 to 200 ng/mL, with a correlation coefficient of 0.998. The detection limit was 0.04 ng/mL at a signal-to-noise ratio of 3. The proposed method offered a platform for fast, sensitive and simultaneous determination for serum samples.

Effect of Filler Geometry on Coefficient of Thermal Expansion in Carbon Nanofiber Reinforced Epoxy Composites

This study involves the investigation of the geometry effect of nano-fillers on thermally induced dimensional stability of epoxy composites by experimentally evaluating the linear coefficient of thermal expansion (CTE). Carbon nanofibers (CNF) were chosen as the filler in epoxy matrix to investigate the effect of an aspect ratio on the CTE of the nanocomposites at three different volume fractions of 0.5, 1, and 2% of the nano-filler. The composites were fabricated using a mechanical mixing method. The CTE values were evaluated by measuring thermal strains of the composites and also compared with a micromechanics model. It was observed that the composites with short CNF (average L/d = 10) show better thermal stability than one of the composites with long CNF (average L/d = 70), and the thermal stability of the composites was proportional to the volume fraction of the filler in each composite. In addition, the CTE of mutliwalled carbon nanotubes (MWNT) reinforced epoxy composites was evaluated and compared with the CTE of the CNF reinforced composites. Interestingly, the MWNT reinforced composites show the greatest thermal stability with an 11.5% reduction in the CTE over the pure epoxy. The experimental data was compared with micromechanics model.

Electrophoretic deposition of carbon nanotubes and bioactive glass particles for bioactive composite coatings

The production of bioactive coatings consisting of 45S5 Bioglass ® and mutli-walled carbon nanotubes (CNTs) by electrophoretic deposition (EPD) was investigated. In addition to pure Bioglass ® coatings, the co-deposition and sequential deposition of Bioglass ® particles (size <5 μm) and CNTs on stainless steel substrates were carried out in order to fabricate bioactive, nanostructured composite layers. The optimal experimental conditions were determined using well-dispersed suspensions by means of a trial-and-error approach by varying the relevant EPD parameters: applied voltage and deposition time. SEM images demonstrated the successful fabrication of Bioglass ®/CNT composites by revealing their morphology and topography. The co-deposition of Bioglass ® particles and CNTs resulted in homogenous and dense coatings exhibiting the presence of well-dispersed CNTs placed in-between micron-sized Bioglass ® particles. This network of high-strength CNTs embedded in the glass layer could act as reinforcing element leading to higher mechanical stability of the coatings. The coatings obtained by sequential deposition offered a two-dimensional nanostructured fibrous mesh of CNTs covering the Bioglass ® layer thus providing a controlled (ordered) nano-topographical surface. This surface nanostructure has the potential to promote the attachment and growth of osteoblast cells and to benefit the formation of bone-like nanosized hydroxyapaptite crystals in contact with body fluids.

In vitro investigation of TiO 2, Al 2O 3, Au nanoparticles and mutli-walled carbon nanotubes cyto- and genotoxicity on lung, kidney cells and hepatocytes

In vitro investigation of TiO 2, Al 2O 3, Au nanoparticles and mutli-walled carbon nanotubes cyto- and genotoxicity on lung, kidney cells and hepatocytes

Sol−Gel-Derived Ceramic−Carbon Nanotube Nanocomposite Electrodes: Tunable Electrode Dimension and Potential Electrochemical Applications

Nanocomposite electrodes made of sol-gel-derived ceramic-carbon nanotube are fabricated by doping mutliwalled carbon nanotubes (MWNTs) into a silicate gel matrix. The electrochemical behavior and potential electrochemical applications of the ceramic-carbon nanotube nanocomposite electrodes (CCNNEs) are also studied. The as-prepared CCNNEs exhibit a tunable dimension ranging from conventional electrode to nanoelectrode ensemble (NEE), depending on the amount of the MWNT dispersed in the silica sol and finally doped within the gel matrix. A high content of the MWNT (i.e., higher than 1.5 mg/mL in the sol) leads to the formation of the CCNNE characteristic of an electrode of conventional dimension, while a low content (typically lower than 0.10 mg/mL) essentially yields the CCNNE like a nanoelectrode ensemble. The NEE is demonstrated to possess good electrocatalytic activity toward the oxidation of ascorbic acid (AA), and the CCNNE of conventional dimension is found to possess remarkable electrocatalytic activity toward the oxidation of glutathione (both reduced and oxidized forms, GSH and GSSG). These properties of the CCNNEs essentially offer a new electrochemical approach for the detection of AA, GSH, and GSSG. The possible essence of the tailor-made dimensions of the CCNNEs is also presented and discussed.

Comment on “Magnetoresistance and differential conductance in mutliwalled carbon nanotubes”

Jeong-O Lee et al. [Phy. Rev. B, 61, R16 362 (2000)] reported magnetoresistance and differential conductance measurements of multiwalled carbon nanotubes. The observed aperiodic conductance fluctuations and the negative magnetoresistance was interpreted to originate exclusively from changes in the density of states at the Fermi energy. We show that this interpretation is questionable and not supported by their measurements.