Well-dispersed Multi-walled Carbon Nanotubes Research Articles

Reconfigurable light-responsive liquid crystal elastomer /carbon nanotube nanocomposite actuators operated by photothermal effects and dynamic exchange reaction

Monodomain liquid crystal elastomers (MLCEs), exhibiting a light-induced dynamic exchange reaction (DER) and light-triggered actuation abilities, were prepared using dispersed multiwalled carbon nanotubes (MWCNTs) and allyl sulfide linkages incorporated in the MLCE matrix. MWCNTs were dispersed in the MLCE matrix using a newly synthesized dispersant, poly(4-cyanobiphenyl-4′-oxyundecylacrylate-co-pyrene methyl acrylate); this dispersant exhibited amphiphilic properties of π–π interactions with the MWCNT fillers (attributed to the pyrene moieties) and miscibility with the MLCE matrix (attributed to the cyanobiphenyl mesogenic moieties). A low amount of well-dispersed MWCNTs (≤0.05 wt%) in the MLCE matrix induced excellent photothermal effects under near-infrared (NIR) light irradiation, leading to considerable reversible contraction/extension actuation (∼40 % change in length). The bilayer film comprising the MLCE and PLCE (PLCE: polydomain LCE) composite films bonded via DER without glue exhibited excellent bending actuation under NIR light irradiation and was configured into several actuators such as a flower-shaped actuator, a weightlifter, a circular rolling band, an oscillator mimicking a hummingbird, and a casting catapult. Therefore, this novel MLCE/CNT composite film enhances the design ability for the arbitrary shaping and functionalization of NIR light-triggerable LCE actuators, which can be applied to several interesting soft robots.

Spatial degradation characteristics and numerical prediction for life of MWCNTs-reinforced concrete by salt freezing

Nanotechnology is of great importance towards the multiscale enhancement of mechanical strength, anti-cracking, corrosion and/or abrasion resistance of concrete. To optimize the durability of concrete structure in a frigid and saline environment, the multi-walled carbon nanotubes (MWCNTs) were introduced along with the evaluation of spatial deterioration characteristics and numerical prediction for its service life in this work. The degree and mechanism of salt freeze-thaw damage relief of MWCNTs-reinforced concrete (CNTC) were investigated by establishing relief rate (Rf, RE and Rp) and damage parameters (Df, DE and Dp) in terms of compressive strength, relative dynamic elastic modulus and porosity. Macroscopic results showed that the presence of MWCNTs substantially delayed the evolution of spatial damage of concrete. The optimum dosage of MWCNTs for the degradation mitigation was also determined to be 0.05 wt% from the microscale scanning electron microscopy, mercury intrusion and mesoscale X-CT scanning techniques, which was responsible to the well-dispersed MWCNTs without entanglement. The synergic effects of filling, nucleation and bridging of MWCNTs in hydrating concrete decreased the porosity and effectively inhibited micro-crack propagation of concrete under the salt freezing effects. Besides, the evolutionary relationships between Df, DE and Dp were established, and a three parameters-dependent prediction index D had been established on the basis of the entropy method and grey system theory GM(1,1) model. The experimental results were in good agreement with the prediction model, and further showed that the salt- freeze-thaw damage of CNTC was significantly reduced.

Multi-Active Sites Loaded NiCu-MOF@MWCNTs as a Bifunctional Electrocatalyst for Electrochemical Water Splitting Reaction.

Water can be sustainably and ecologically converted by electrocatalysts into hydrogen and oxygen, which, in turn, can be converted into energy. However, the advancement of using water as green energy is hampered by limitations in the study of high-performance catalysts. The purpose of this study was to construct an electrocatalyst by anchoring well-dispersed multiwalled carbon nanotubes (MWCNTs) on nickel-copper (NiCu-MOF) nanoblocks through a simple solvothermal method. The synthesis of NiCu-MOF@MWCNTs demonstrated exceptional electrocatalytic performance for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in an alkaline medium. At 10 mA cm-2 in 1.0 M KOH, the OER and HER performance of the catalyst displays a relatively low overpotential, with only 220 and 78 mV, respectively. Furthermore, the catalytic activity remained unchanged for 24 h in 1.0 M KOH. This performance was superior to the majority of electrocatalysts that have been reported. This was achieved by utilizing the strong synergy that exists between MWCNTs and bimetallic (Ni-Cu) nano blocks present in the metal-organic framework. The enhanced electrocatalytic activity of the nanocomposite can be attributed to the synergistic impact caused by its various components.

Bimetallic FeCo metal-organic-frameworks anchored multi-walled carbon nanotubes for electrochemical nitrite sensing

A heterostructured nanocomposite modified electrode was designed as a sensitive and efficient analytical tool for nitrite determination. The nanocomposite constructed from different building blocks was fabricated by ultrasonically growing bimetallic FeCo metal-organic framework (MOF) in the well-dispersed multi-walled carbon nanotubes (MWCNTs) suspensions at room temperature, where the MOF hybrid was extended to uniform thin film structure. Electrochemical experimental results demonstrate that the synergistic contributions from bimetallic active sites, MWCNTs and thin-film morphology endow modified electrode with dramatically enhanced catalytic activity metrics towards nitrite. Significantly, the co-doping of Fe-Co plays key role in improving the electronic conductivity and catalytic capacity of the MOF/MWCNTs composite. Thereinto, the FeCo-MOF/MWCNTs sensor displays excellent detection performance with a wide linear detection range (5∼5000 μM), outstanding selectivity and a detect limitation of 1.68 μM for nitrite. These superior findings provide new potentials application for the inspection of nitrite in environmental monitor.

Decorative Multi-Walled Carbon Nanotubes by ZnO: Synthesis, Characterization, and Potent Anti-Toxoplasmosis Activity

Toxoplasmosis may become a fatal disease in immunodeficient, diabetic patients, pregnant women, and infants. Hence, the diligent search for new effective treatment is among the major concerns worldwide. The well-dispersed multi-walled carbon nanotubes lined with ZnO (ZnO-MWCNT), graphene oxide (GO-NPs), and zinc oxide (ZnO-NPs) were successfully synthesized through rapid and facile hydrothermal arc discharge technique (HTADT). The antiparasitic effects of ZnO-NPs, GO-NPs, and ZnO-MWCNT were investigated in mice infected with Toxoplasma gondii. The percent of tachyzoites reduction were detected. The observed results demonstrated that ZnO-MWCNT revealed a significant reduction in the parasite count reached 61% in brain tissues, followed by liver (52%), then spleen (45%). The assessments of antiparasitic, inflammatory, and anti-inflammatory cytokines confirmed the superior activity of ZnO-MWCNT as antiparasitic agent, which paves the way for the employment of ZnO-MWCNT as a treatment for the acute RH strain of T. gondii infection in vivo.

Surface-fractal-dimension characteristics of cementitious composites with multi-walled carbon nanotubes dispersed by silica fume

The effects of adding silica fume and multi-walled carbon nanotubes (MWCNTs) to cement mortar on its pore surface fractal dimension (SFD) are analyzed. The SFD is expressed through the Zhang and Li model based on mercury intrusion porosimetry (MIP) experiments. The silica fume serves as a filler and pore refiner for the paste and increases the SFD of the mesopores by forming a C–S–H gel through the pozzolanic reaction. Additionally, the well-dispersed MWCNTs increase the SFD by complicating the surfaces of the mesopores. The silica fume and MWCNTs considerably change the pore structure of the mesopores, but do not significantly affect the capillary pores. Although the correlation between the SFD and compressive strength of the cement mortar is rather poor, it has been shown to have an exponentially proportional relationship overall. Further, the SFD of the capillary pores has a greater effect than that of the mesopores on the compressive strength because of the load concentration effect.

Chemically Coupled Cobalt Oxide Nanosheets Decorated onto the Surface of Multiwall Carbon Nanotubes for Favorable Oxygen Evolution Reaction.

Cobalt oxide has been widely investigated among potential transition metal oxides for the electrochemical energy conversion, storage, and water splitting. However, they have inherently low electronic conductivity and high corrosive nature in alkaline media. Herein, we propose a promising and facile approach to improve the conductivity and charge transport of cobalt oxide Co₃O₄ through chemical coupling with well-dispersed multiwall carbon nanotubes (MWCNTs) during hydrothermal treatment. The morphology of prepared composite material consisting of nanosheets which are anchored on the MWCNTs as confirmed by scanning electron microscopy (SEM). A cubic crystalline system is exhibited by the cobalt oxide as confirmed by the X-ray diffraction study. The Co, O, and C are the only elements present in the composite material. FTIR study has indicated the successful coupling of cobalt oxide with MWCNTs. The chemically coupled cobalt oxide onto the surface of MWCNTs composite is found highly active towards oxygen evolution reaction (OER) with a low onset potential 1.44 V versus RHE, low overpotential 262 mV at 10 mAcm-2 and small Tafel slope 81 mV dec-1. For continuous operation of 40 hours during durability test, no decay in activity was recorded. Electrochemical impedance study further revealed a low charge transfer resistance of 70.64 Ohms for the composite material during the electrochemical reaction and which strongly favored OER kinetics. This work provides a simple, low cost, and smartly designing electrocatalysts via hydrothermal reaction for the catalysis and energy storage applications.

Effect of functionalized multi-walled carbon nanotubes on mechanical properties and durability of cement mortars

This article deals with the effects of using COOH functionalized multi-walled carbon nanotubes (MWCNTs) on mechanical properties and durability of cement mortars. In this study, the behavior of nanocomposites modified with well-dispersed MWCNTs at 0.05, 0.1, 0.2, 0.3, and 0.4 wt percent of cement using compressive and flexural strength tests subjected to environmental conditions of combined sodium-magnesium sulfate and limestone-saturated water up to long-term exposure of 960 days were analyzed. The results revealed that adding functionalized MWCNTs as a bridging factor increases the flexural strength of nanocomposites stored in limestone-saturated water and sulfate solution by 37% and 42%, respectively. Moreover, as a filler, by refining pores and changing the microstructure, it improved compressive strength in the two mentioned environments by 25% and 39%, respectively.

Surfactant-free one-step fabrication of gelatin/PAAm/MWCNT composites for biomedical applications

Well-dispersed multiwalled carbon nanotube (MWCNT) and gelatin-enhanced polyacrylamide (PAAm) composites were synthesized via a free-radical copolymerization method. MWCNTs were added to the composite mixture in various amounts (0.5 mg, 1.0 mg, 1.5 mg, and 2.0 mg) during the nucleation process in order to increase the conductivity. Gelatin/PAAm/MWCNT composites containing different amounts of MWCNTs were then characterized using the ultraviolet–visible (UV–vis) spectroscopic technique to illuminate the dispersibility, and optical properties of the composites. Bandgap energies were evaluated by measuring the absorbance spectra of the composites in a quartz cuvette of the UV–vis spectrophotometer. By calculating the resonance ratio and normalized width values from the absorption response of the composites according to the wavelength, the dispersion rate of the MWCNTs in the composite matrix was determined. The proper ultra-sonication process has been realized so as to maintain the good dispersion of the MWCNTs inside the polymeric matrix lowering the normalized width and increasing the resonance ratio. Polymeric composite materials based on carbon nanotubes are of considerable interest for a variety of biomedical applications. Furthermore, in this work, it is argued that the use of gelatin, another biocompatible material, together with MWCNT makes the properties of the formed composite, suitable for the desired biomedical applications.

Cement paste with well-dispersed multi-walled carbon nanotubes: Mechanism and performance

The research of functional cement composite materials has always been the focus in the field of concrete. Multi-walled carbon nanotubes (MWCNTs) as one of the conductive fillers can significantly improve the mechanical and electrical properties of concrete. However, the addition of MWCNTs seriously affects the fluidity of cement paste and the distribution of internal particles, which limit the full potential of MWCNTs. In this paper, the dispersion mechanism and performance improvement of cement paste with well-dispersed multi-walled carbon nanotubes are systematically studied from the perspective of expanded DLVO (EDLVO) theory analysis, microscopic ESEM image observation and macroscopic performance measurement. The results of the EDLVO theory indicate that the polar interaction energy between MWCNTs particles is the main cause of agglomeration, and the entanglement of MWCNTs particles in cement paste are observed in ESEM images. The comparison of dispersants shows that under the same fluidity, the addition of polycarboxylate superplasticizer (PCE) guarantees better mechanical properties than sodium dodecyl sulfate (SDS). Experimental results of hardened cement paste with PCE show that at the age of 28 days, when the MWCNTs content is 0.1%, 0.3% and 0.5%, the flexural strength can be increased by 12.9%, 15.8% and 2.0%, respectively, and the resistivity can be reduced by 16.9%, 19.7% and 40.3%, respectively. Cement paste with well-dispersed MWCNTs obtains excellent mechanical and electrical properties, which lay a foundation for the utilization of MWCNTs in cement composite as the electrothermal materials in practical engineering.

Multielement Synergetic Effect of Boron Nitride and Multiwalled Carbon Nanotubes for the Fabrication of Novel Shape-Stabilized Phase-Change Composites with Enhanced Thermal Conductivity.

Shape-stabilized phase-change composites (SSPCCs) have been widely applied for thermal energy storage and thermal management because of their excellent properties. To further improve their thermal conductivity and thermal cycling stability, we successfully designed and synthesized a series of SSPCCs with three-dimensional (3D) thermally conductive networks by exploiting the synergistic effect between one-dimensional (1D) carbon nanotubes (CNTs) and two-dimensional (2D) hexagonal boron nitride (h-BN). The interconnected thermally conductive network composed of h-BN and multiwalled carbon nanotubes (MWCNTs) enhanced the SSPCC performance. The micromorphologies of the prepared SSPCCs revealed that well-dispersed MWCNTs, hydroxylated h-BN, and polyethylene glycol (PEG) molecular chains effectively bonded into a 3D cross-linking structure of the SSPCCs. Moreover, the chemical and crystalline structural and thermal properties and thermal cycling stability of the novel SSPCCs were systematically investigated by various characterization techniques. The presence of a 3D thermally conductive network in the as-synthesized SSPCCs evidently improved the shape stability, phase-change behavior, and thermal stability. Benefiting from the 3D nanostructural uniqueness of SSPCCs, the thermal conductivity of SSPCC-2 was up to 1.15 W m-1 K-1, which represented a significant enhancement of 239.7% compared with that of pure PEG. Meanwhile, the efficient synergistic effect of h-BN and MWCNTs remarkably enhanced the heat-transfer rate of the SSPCCs. These results demonstrate that the prepared SSPCCs have potential for applications in thermal energy storage and thermal management systems. This study opens a new avenue toward the development of SSPCCs with good comprehensive properties.

Covalent Functionalization of Multi-Walled Carbon Nanotubes for Dispersion in Cement Pastes

Abstract Covalent functionalization of multi-walled carbon nanotubes (MWCNTs) were obtained through acidification, γ-Methacryloxypropyl trimethoxy silane (KH-570) treatment, and free radical polymerization using methyl allyl polyethenoxy ether (HPEG). Fourier-transformed infrared spectroscope was employed to determine the composition and structural changes of MWCNTs after modification. The dispersion of MWCNTs modified by HPEG in water at pH∼13 was determined by UV-vis-NIR. In addition, the effects of modified MWCNTs on cement hydration were investigated to describe the dispersibility of MWCNTs in cement pastes indirectly. Results show that oxygen functional groups generated on the surface of MWCNTs after acidification and KH-570 grafted on acidified MWCNTs through ≡Si–O–C≡ before radical polymerization with HPEG. MWCNTs modified by HPEG exhibit better dispersibility than pristine MWCNTs in a simulated cement pastes environment prepared at pH∼13. The additions of functionalized MWCNTs (P3-S-MWCNTs) promote the hydration of cement pastes indicated from isothermal conduction calorimeter measurement and X-ray diffraction analysis. Scanning electron microscopy observation confirmed the good dispersibility of functionalized MWCNTs in cement pastes. The promoting effect on cement hydration of P3-S-MWCNTs may attribute to the well-dispersed MWCNTs. The dispersed MWCNTs can act as the nucleating agent for carbon-sulfur-hydrogen and carbon-hydrogen, thus promoting the hydration of cement.

Synergistic Effect of Nickel Nanoparticles and Carbon Nanotubes Buckypaper for Enhancement of Microwave Shielding Properties

Carbon nanotubes (CNTs) are considered as the most promising materials to solve the electromagnetic interference (EMI) issue. Various forms of CNTs including CNTs/polymer composites, metal nanoparticles-decorated CNTs and freestanding CNT buckypapers (CNT BPs) have been proposed to enhance shielding effectiveness. In this study, the synergistic effect of nickel nanoparticles (NPs) and relatively short CNTs for the enhancement of microwave shielding properties was investigated. CNT BPs were prepared by vacuum filtration of well-dispersed multi-walled CNTs and subsequently nickel was decorated on the CNT BPs (Ni/CNT) by pulsed DC sputtering technique with different deposition times of 0, 5, 10 and 15 min (hereinafter referred to as CNi0, CNi05, CNi10 and CNi15, respectively). The diameter of Ni/CNT increased from 8.74±0.53 to 72.5±3.2 nm and the conductivity improved from 9.57±0.87 to 12.57±0.59 S/cm when the nickel deposition time was 15 min. Nickel NPs were the mixed phases of nickel and nickel oxide with a dominant nickel phase. The shielding effectiveness at the frequency of 9.5 GHz achieved to -34.1 dB for CNi15. The enhancement of shielding effectiveness of CNi15 is attributed to the synergistic effect of CNTs and nickel NPs on wave dissipation

An image-driven finite element modeling method for evaluating the stress and strain distribution in carbon nanotubes/epoxy composites

Due to the complex morphology of carbon nanotubes (CNTs) in an epoxy resin, it is difficult to establish finite element (FE) models using common methods. Therefore, this study introduces an approach using real TEM images of CNTs/epoxy composites to establish FE models and obtain real stress and strain distributions. Two kinds of multi-walled carbon nanotubes (MWCNTs), unmodified and plasma-treated MWCNTs, were also used to investigate the effects of the dispersion state of MWCNTs on the mechanical properties of MWCNTs/epoxy composites. Due to the real-shape models, the simulation results clearly showed that well-dispersed MWCNTs more effectively transferred stresses, and thus reduced localized stress concentration and improved the deformation resistance in composites. The composite with poorly-dispersed MWCNT exhibited a higher stress concentration at MWCNTs and more severely strained areas in the epoxy resin. In this case, debonding was very likely to occur at the interface of the two substances, and caused the formation of preliminary cracks in the components.

Tribological behavior of unsaturated polyester hybrid composites containing wood flour and carbon nanotubes

The dry-wear behavior of hybrid composites comprising of multi-walled carbon nanotubes (MWCNTs) and wood flour (oil palm kernel shell powder) within an unsaturated polyester matrix was investigated in this paper. The results revealed that the incorporation of wood flour -even at little as 10 wt% filler content- significantly improved the tribological behavior of the composite. This improvement in tribological behavior was attributed to the transfer of a soft layer of wood flour on the worn area during the wear process, which acted as a self-lubricating material. Investigation of the effect of filler size revealed that composites containing smaller filler sizes exhibited higher values of friction coefficient (µ) and specific wear rate (Ws). This reduction attributed to the creation of a surface with a lower surface roughness (Ra) at the worn area which resulted in a larger number of contacts between counterpart surfaces. In addition, increasing in the normal load resulted in a considerable increment in the values of µ and Ws. Filler treatment with hot alkali solution (1 to 9 wt% concentration) showed that both µ and Ws reached their minimum values at 5 wt% alkali concentration due to improved interfacial bonding between the filler and matrix. Finally, a relatively small amount (0.2 wt%) of well-dispersed MWCNTs within the wood flour polyester composite was found to be capable of improving the tribological behavior of such hybrid composites.

Processing-Mediated Different States of Dispersion of Multiwalled Carbon Nanotubes in PDMS Nanocomposites Influence EMI Shielding Performance.

Advancement in wireless technology has increased the usage of wireless devices extensively in the past few years, which led to an increase in electromagnetic interference (EMI) in the environment. Extensive research on fabrication of EMI shielding materials has been done. However, the role of processing method of polymer composites in EMI shielding has been neglected. In this work, we investigate the role of two polymer processing methods, spin coating and compression molding, in EMI shielding application. Poly(dimethylsiloxane) (PDMS) nanocomposites with multiwalled carbon nanotube (MWCNT) were spin-coated onto glass slides and compression-molded to a similar thickness. The processing method that exhibited the best shielding was employed to fabricate multiple PDMS composites comprising different compositions of MWCNT and Fe3O4 and stacked to form a multilayered EMI shielding PDMS composite. Scanning electron micrographs revealed that MWCNT in spin-coated composites are significantly more agglomerated than in the compression-molded film. Direct current conductivity and curing temperature were higher in compression-molded films as the filler formed a well-percolated network and hindered cross-linking of polymer chains. EMI shielding results revealed that spin-coated films demonstrated greater shielding effectiveness than compression-molded composites in the Ku-band (12–18 GHz). Individual agglomerates of MWCNT in spin-coated film attenuated incoming electromagnetic radiation more effectively than well-dispersed MWCNT in compression-molded films. Therefore, PDMS composites of different compositions of MWCNT and Fe3O4 nanoparticles were prepared through spin coating and stacked with a gradient of filler concentration, which resulted in maximum shielding of −28 dB, i.e., shielding more than 99% of incoming EM radiation by a 0.9 mm film.

Investigation of optical and electrical properties of MWCNT/rGO/poly(3-hexylthiophene) ternary composites

Filler-induced structural modification portrays a crucial role in altering physical properties of polymer composites. A new approach by introducing 1D and 2D nanostructures into the conjugated polymer matrix could enhance structural, optical and electrical properties of the composites. A ternary composite prepared by introducing different wt% of multiwalled carbon nanotubes (MWCNTs) into the reduced graphene oxide (rGO)/poly(3-hexylthiophene-2,5-diyl) (P3HT) host matrix has been investigated. Structural and morphological investigations revealed a change in the crystalline size as well as conjugation length of the polymer units that could be attributed for tailoring the optical, electrical as well as electrochemical properties of the composites. The π–π interaction has been attributed to the observed shift in the redox potentials after incorporation of MWCNTs and rGOs into the P3HT host matrix. Improvement in electrical properties of the composites after incorporation of MWCNTs and rGOs has been attributed to softening of the interfacial grain boundary by the 3D network structure created by the well-dispersed MWCNTs and rGOs in the P3HT matrix.

Effective Network Formation of PEDOT by in-situ Polymerization Using Novel Organic Template and Nanocomposite Supercapacitor

Different π-conjugated sulfonate templates, including dodecylbenzenesulfonate (DBS), 2-naphthalenesulfonate (NAS), N,N’-bis(2,6-diisopropylphenyl)-perylenediimide-1,6,7,12-tetraoxyphenylsulfonate (PTS), as well as auxiliary assistance by graphene (Gra) and multi-walled carbon nanotube (MWCNT), have been utilized to investigate the polymerization behavior of 3,4-ethylenedioxythiophene (EDOT) and the influence on the corresponding morphologies and properties. PEDOT has been self-polymerized with obviously agglomeration without template. Isolated PEDOT grains with coiled shape have been formed by DBS template polymerization. More crystalline and conductive PEDOT with quinoid-conformation and ordered arrangement has been developed by utilizing template with novel π conjugated sulfonate (PTS). Most prominently, the obtained conductive PEDOT:MWCNT shows continuous interpenetrating network structure with more extended PEDOT and well-dispersed MWCNT due to π-π interaction of PEDOT with noncovalent functionalized MWCNT by electron-deficient conjugated sulfonate. Furthermore, a high specific capacitance of 199Fg−1 at current density of 0.5Ag−1 for PEDOT:MWCNT has also been demonstrated successfully for owning potential applications in supercapacitors.

Non-covalent modified multi-walled carbon nanotubes: dispersion capabilities and interactions with bacteria

Antimicrobial activity of surfactant-modified multi-walled carbon nanotubes (MWCNTs) was investigated by analyzing the growth curves of an Escherichia coli (E. coli) population in ionic and non-ionic surfactant-modified MWCNTs in Luria Bertani (LB) broth. The ionic surfactants (sodium dodecylbenzenesulfonate (SDBS), sodium cholate (SC), dodecyltrimethylammonium bromide (DTAB), cetyltrimethylammonium bromide (CTAB)) as well as a non-ionic polyvinylpyrrolidone (PVP) were used to test the dispersion and resulting antimicrobial effect of MWCNTs by means of UV–vis spectroscopy and optical density (OD) measurement. Among these surfactants, SDBS and DTAB provided maximum and minimum MWCNT dispersion, respectively. Furthermore, the biocompatibility issues with respect to dispersion capabilities of the ionic and non-ionic surfactants is discussed in detail, as a source of potential misinterpretation of the obtained growth curves of E. coli and thus, their antimicrobial effect. Finally, scanning electron microscopy was used to study the interaction of well-dispersed MWCNTs with the E. coli cells.

Strength, energy absorption capability and self-sensing properties of multifunctional carbon nanotube reinforced mortars

The development of multifunctional self-sensing mortars reinforced with multi wall carbon nanotubes (MWCNTs) is herein carried out. The purpose is twofold: to determine the impact of nano-modification on the strength, the stiffness, and the toughening effect that MWCNTs can provide; and to evaluate the multi-functionality and smartness of cement mortars, reinforced with 0.08, 0.1, 0.3 and 0.5wt% of cement well-dispersed MWCNTs. The experimental determination of the mechanical properties of 3, 7 and 28d nanomodified mortars was achieved through three point bending, uniaxial compression, and fracture mechanics experiments. The evaluation of the smartness of the nanoreinforced mortars was achieved by measuring the fractional change in the electrical resistance of specimens, induced by external cyclic compressive loading in the elastic region. The excellent reinforcing capability of MWCNTs is demonstrated by a significant improvement in flexural strength (87%), Young’s modulus (92%), flexural toughness (83%), first crack strength (64%) and first crack toughness (65%). Results from piezoresistivity experiments confirm that the nanoreinforced mortars exhibit an increased change in resistivity under cyclic compressive loading, which is indicative of the amplified sensitivity of the material in strain sensing.