Nanotube Content Research Articles

Lithium-Calcium Greases Having Carbon Nanotubes and Aluminum Oxide Base Nanoadditives: Preparation and Characteristics of Nanogrease.

This research presents the results of the effect of different concentrations (2, 4, 6, and 8 wt %) of multiwall carbon nanotubes (MWCNTs) and aluminum oxide nanoparticles (Al2O3) on the characteristics of lithium-calcium grease (LCG). The LCG/Al2O3 and LCG/MWCNT were studied and illustrated by measuring the dropping point, consistency, thermal conductivity, and tribological characteristics of nanograins (wear, friction, and welding point) by using a four-ball tribometer. The morphologies of the additives and the nanogrease were examined and evaluated by X-ray diffraction and transmission electron microscopy. The worn surface of the ball surface was assessed by scanning electron microscopy. Based on the obtained results, the nanoadditive can significantly enhance the grease properties. The grease having a 4 wt % content of Al2O3 and MWCNT presented the lowest wear scar diameter and friction coefficient. Consequently, the welding point, dropping point, and thermal conductivity indicated that adding nanoadditives could strikingly enhance the lubricating effect of grease by 26, 32, and 75%, respectively. Finally, this study provides a lubricant with promising results that can be used under extreme pressure.

Piezoresistive Characteristics of Carbon Nanotube Polymer Composites with Different Filler Content and Aspect Ratio for Pressure Sensors

Polymer composites enriched with conductive fillers hold immense potential for flexible pressure sensors, because of the remarkable piezoresistive effect they possess. Research on polymer composite pressure sensors has been actively ongoing because of their flexibility and high electrical resistance performance. This paper presents a comprehensive comparison of the piezoresistive characteristics of conductive composites for pressure sensors, focusing on the influence of carbon nanotube (CNT) content and aspect ratio. Polymer composites with conductive fillers, specifically CNTs, have demonstrated significant potential for pressure sensing applications based on the piezoresistive effect. By systematically varying the CNT concentration and aspect ratio, we investigated the impact of these parameters on the piezoresistive behavior of the composites. A pressure in the range of 0-200 kPa was applied to the conductive composite, and resistance change due to pressing was measured. The best performing samples were evaluated in 150 cycle tests to verify repeatability and durability. Experimental analysis and characterization revealed the intricate relationship between CNT content, aspect ratio, and the resulting piezoresistive properties. Through this study, we aim to enhance understanding of how CNT concentration and aspect ratio influence the performance of CNT/PDMS composites as pressure sensors, thereby facilitating the development of optimized sensing materials for various pressure sensing applications.

Desulphurization of Simulated Oil Using SAPO-11 with CNT's as Adsorbent: A Kinetic Study

In this study, sulfur was removed from imitation oil using oxidative desulfurization process. Silicoaluminophosphate (SAPO-11) was prepared using the hydrothermal method with a concentration of carbon nanotubes (CNT) of 0% and 7.5% at 190 °C crystallization temperature. The final molar composition of the as-prepared SAPO-11 was Al2O3: 0.93P2O5: 0.414SiO2. 4% MO/SAPO-11 was prepared using impregnation methods. The produced SAPO-11 was described using X-ray diffraction (XRD) and Brunauer-Emmet-Teller (N2 adsorption–desorption isotherms). It was found that the addition of CNT increased the crystallinity of SAPO-11. The results showed that the surface area of SAPO-11 containing 7.5% CNT was 179.54 m2/g, and the pore volume was 0.317 cm3/g. However, the surface area of SAPO-11 containing 0% CNT was 125.311 m2/g, and pore volume was 0.275 cm3/g, while nanoparticles with an average particle diameter of 24.8 nm were obtained. Then, the prepared SAPO-11 was used in the oxidative desulfurization process. The oxidative desulfurization was studied using several factors affecting desulfurization efficiency, such as time (40, 60, 80, 100, and 120) min, amount of MO/SAPO-11 (0.3, 0.4, 0.5, 0.6, and 0.7) g/100 ml of simulated oil (100 ppm of dibenzothiophene), the amount of hydrogen peroxide (4ml) oxidizer/100 ml of simulated oil, and the temperature ranges from (40, 50, 60, 70, and 80 °C). The results showed that an increase in MO/SAPO-11 led to an increase in desulfurization. The best removal percentage for sulfur content was 92.79%, obtained at 70 °C and 0.6 g of MO/SAPO-11 containing 7.5% CNT, and the removal was 82.34% at 0% CNT and the same other conditions. While the equilibrium was achieved after 100 min. The results revealed that Freundlich's model described the adsorption of sulfur compounds better than Langmuir's, where the R2 of the Freundlich model was 0.9979 and the R2 of the Langmuir model was 0.9554.

Effect of Nanoparticle and Carbon Nanotube Additives on Thermal Stability of Hydrocarbon-Based Drilling Fluids

The article presents the results of experimental study on the effect of additives of silicon oxide nanoparticles, as well as single-walled and multi-walled carbon nanotubes on the colloidal stability and thermal degradation process of hydrocarbon-based drilling fluids. Such a comprehensive study of hydrocarbon-based drilling fluids was carried out for the first time. The effect of the concentration and size of silicon oxide nanoparticles, as well as the type and concentration of nanotubes on the colloidal stability of drilling fluids during thermal aging tests at different temperatures, was investigated. The nanoparticle size varied from 18 to 70 nm, and the concentration ranged from 0.25 to 2 wt.%. Single-walled and multi-walled nanotubes were studied, whose concentration varied from 0.01 to 0.5 wt.%. The thermal aging temperature varied from 30 to 150 °C. According to the results of the investigation, it was shown that the temperature stability of hydrocarbon-based drilling fluids can be significantly improved by adding the above substances. At the same time, it was shown that the use of single-walled nanotubes for thermal stabilization of drilling fluids was several times more effective than the use of multi-walled nanotubes, and tens of times more effective than the use of spherical silicon oxide nanoparticles.

Enhancement of carbon nanotubes on microalgal-fungal consortium formation and wastewater treatment

As a promising material with an efficient light capture capability, a low amount of carbon nanotubes can affect growth and photosynthesis by regulating microalgal cells, thereby enhancing the pollutant removal efficiency in wastewater. In this study, microalgal-fungal consortia of Chlorella vulgaris and Ganoderma lucidum were developed with different types and concentrations of carbon nanotubes. The treatment effect of microalgal-fungal consortia on simulated digestate was also studied. The results demonstrate that 1.5 mg/L of carboxylated multi-walled carbon nanotubes remarkably promoted the formation, growth and photosynthesis of consortium. The dry weight and chlorophyll a content reached 19.3 ± 0.53 mg/symbiont and 27.3 ± 0.52 μg/L, respectively. Moreover, the removal efficiency of chemical oxygen demand, total nitrogen, total phosphorus and tetracycline hydrochloride were 94.1%, 65.5%, 61.9% and 96.2%, respectively. Overall, these findings suggest a promising future for the use of carbon nanotubes in wastewater treatment by regulating microalgal-fungal consortia.

Orientational Transitions in Magnetically Compensated Liquid-Crystal Suspensions of Ferromagnetic Carbon Nanotubes

Purpose of research is to study the influence of ferromagnetic carbon nanotubes on orientational transitions in magnetically compensated liquid-crystal suspensions.Methods. The problem was solved in the framework of the continuum theory. By minimizing the Helmholtz free energy functional, a system of Lagrange-Euler equations is obtained that determines the equilibrium dependences of the orientation angles of liquid crystal and impurity ferromagnetic carbon nanotubes directors, as well as the concentration distributions of the dispersed phase of the suspension as a function of the transverse coordinate, material parameters, and magnetic field strength.Results. It is shown that in the presence of an external magnetic field, a liquid-crystal suspension of ferromagnetic carbon nanotubes can be in a non-uniform phase (angular phase) and two uniform phases (planar and homeotropic phases). Expressions for the threshold fields of transitions between coexisting orientational phases are obtained analytically as functions of the material parameters of the composite. Diagrams of the orientational phases of the suspension are plotted.Conclusion. As a result of the research, it was shown that the addition of low concentrations of ferromagnetic carbon nanotubes can significantly reduce the threshold of the magnetic Fréedericksz transition compared to a pure liquid crystal, which is important for various technical applications. The obtained analytical formulas for the threshold fields of transitions between different orientational phases can be used to determine the anchoring energy and material parameters of suspensions of ferromagnetic carbon nanotubes in a liquid crystal.

Removal of carboxylated multi-walled carbon nanotubes (MWCNT-COOH) from the environment by Trametes versicolor: a simple, cost-effective, and eco-friendly method

Nanotechnology has increased the release of nanoparticles into the environment, which poses a risk to human health and the ecosystem. Therefore, finding ways to eliminate these hazardous particles from the environment is crucial. This research studied the ability of Trametes versicolor fungi to remove carboxylated multi-walled carbon nanotubes. The study analyzed the impact of pH, MWCNT-COOH concentration, and initial fungal growth time on the removal process. The properties of the adsorbent were measured before and after the biosorption process using SEM, FTIR, and EDS techniques. The results showed that the live biomass of T. versicolor was more effective in removing nanoparticles than dead biomass at 30 °C and pH 7. An increase in carbon nanotube concentration from 5 to 20 mg. mL−1 decreased biosorption potential from 100% to 28.55 ± 1.7%. The study also found that an increase in initial fungal growth time led to higher biomass production and adsorption capacity, increasing biosorption ability for concentrations > 5mg. ml−1. The biosorption kinetics followed a pseudo-second-order model and corresponded most closely to the Freundlich isotherm model. The adsorption capacity of live fungal biomass to remove multi-walled carbon nanotubes was 945.17 mg. g−1, indicating that T. versicolor fungi have significant potential for removing carbon nanostructures from the environment.

Electrical and optical properties of polyamide 6 nanocomposites with multi-walled carbon nanotubes

In this work, quantum chemical modeling, electrical conductivity, Raman scattering, and photoluminescence of polyamide 6 nanocomposites with multi-walled carbon nanotubes (0–2.5 vol%) were investigated. It was shown that the concentration dependence of the electrical conductivity obeys the percolation theory and has the value of percolation threshold 1.41 vol%. The conductivity value of the composite at 2.5 vol% nanotubes is 1.1*10-3 S/cm. It was found that in PA6 nanocomposites filled with MWCNT an increase in the concentration of nanotubes from 0.001 to 0.015 vol%, namely in the pre-percolation region of electrical conductivity, due to a significant restructuring of the Raman spectra, which consists in a shift of the vibrational modes of the methylene groups CH2 and amide I, as well as in a change of their relative intensities. From the photoluminescence spectra of PA6-MWCNT, it can be seen, that the carbon nanotubes largely determine the conformational changes in the polymer matrix and have little effect on the defective structure of the polymer itself.The goal: to establish the mechanisms of electrical conductivity and the interaction of nanotubes with polyamide macromolecules and its influence on the electronic and optical properties of nanocomposites of polyamide multi-walled carbon nanotubes.

Comparative analysis of the effect of single-walled and multi-walled carbon nanotube additives on the properties of hydrocarbon-based drilling fluids

The article presents the results of a comprehensive comparative analysis of the effect of single-walled and multi-walled carbon nanotubes on the main performance characteristics of mineral oil-based drilling emulsions. Such a systematic comparative study of hydrocarbon-based solutions has been performed for the first time. Weight concentration of single-walled nanotubes varied from 0.01 % to 0.1 %, and of multi-walled ones, from 0.1 % to 0.5 %. The formulation and preparation technique of stable drilling emulsions with single-walled and multi-walled nanotube additives were practiced. The effect of nanotube additives on rheology, filtration, and antifriction properties, as well as colloidal stability, and clay inhibition kinetics of hydrocarbon-based drilling fluids has been studied. As a result of the study, it has been successfully demonstrated that adding even very small amount of carbon nanotubes allows significantly controlling the main performance characteristics of drilling fluids. Thus, adding just 0.025 wt% of single-walled nanotubes increases effective viscosity of the drilling fluid by about 45 %, the yield stress – by 1.7 times, colloidal stability – by 36 %, reducing at the same time filtration loss by 55 %, and friction factor – by 20 %. At the same time, it has been shown that using single-walled nanotubes is several times more efficient compared to adding multi-walled nanotubes, and hundreds of times more efficient compared to using spherical metal oxide nanoparticles.

Carbon Nanotube-Polyurethane Composite Sheets for Flexible Thermoelectric Materials.

Integration of single-wall carbon nanotubes (SWCNTs) in the form of fabriclike sheets or other preformed assemblies (films, fibers, etc.) simplifies their handling and allows for composites with higher nanotube contents, which is needed to better exploit their outstanding properties and achieve multifunctional materials with improved performance. Here, we show the development of p-type SWCNT-thermoplastic polyurethane (TPU) fabric materials with a wide range of SWCNT contents (from 5 to 90 wt %) by employing a one-step filtration method using a suspension of SWCNTs in a TPU solvent/nonsolvent mixture. The mechanical and thermoelectric (TE) properties of these SWCNT-TPU nanocomposites were tailored by varying the SWCNT/TPU wt % ratio, achieving significant advantages relative to the pristine SWCNT buckypaper (BP) sheets in terms of strength and stretchability. In particular, the SWCNT-TPU nanocomposite with a 50/50 wt % ratio composition (equivalent to 15 vol % of SWCNTs) shows a power factor (PF) of 57 μW m-1 K-2, slightly higher compared to the PF of the SWCNT BP prepared under the same conditions (54 μW m-1 K-2), while its mechanical properties significantly increased (e.g., ∼7-, 25-, and 250-fold improvements in stiffness, strength, and tensile toughness, respectively). These results represent a significant step toward the development of easy-to-process self-supporting and stretchable materials with robust mechanical properties for flexible thermoelectric devices.

Effect of Shellac Microcapsules Blended with Carbonyl Iron Powder and Carbon Nanotubes on the Self-Healing and Electromagnetic Wave Absorption Properties of Waterborne Coatings on Fiberboard Surface

An orthogonal experiment was conducted to prepare nine different coatings by changing four influencing factors of shellac microcapsule content, carbonyl iron powder (CIP) content, the content of carbon nanotubes (CNTs), and primer coating thickness. By testing the morphology and performance of the shellac microcapsules, CIP, CNT blended coatings (SCCBC), and using the elongation at tensile failure of the SCCBC as the orthogonal experimental analysis, it was determined that the biggest factor affecting the elongation at tensile failure of SCCBC was the shellac microcapsule content. With the aim of further optimizing the properties of the SCCBC, a single-factor experiment was performed using shellac microcapsule content as the sole variable, and it was determined that the SCCBC exhibited optimal performance when shellac microcapsule content reaches 4.2%. The optical properties of SCCBC were tested, showing that there were minor fluctuations in the glossiness and color difference of the SCCBC. The mechanical properties of SCCBC were tested. The presence of shellac microcapsules can contribute to an improvement of the SCCBC toughness, restraining the formation of microcracks, and have a certain self-healing effect. The electromagnetic wave absorption properties of the mixed powder of shellac microcapsules, CIP and CNTs were tested. The CIP and CNTs can enhance the electromagnetic wave absorption properties of the waterborne coating, but the electromagnetic wave absorption properties were weaker in low-frequency bands. The SCCBC on the surface of fiberboard not only have a self-healing effect, but also have a certain electromagnetic wave absorption function through the mixing of shellac microcapsules, CIP, and CNTs, expanding the application range of waterborne coatings for wood.

Composite stability and electro-optical properties of carbon nanotubes/5CB-based nematic hybrid liquid crystals

ABSTRACT This study examined the impact of different concentrations of carbon nanotubes (CNTs) on five nematic hybrid liquid crystals (LCs) based on 5CB. Electro-optical properties of the composite were tested, and the interaction between CNTs and LCs was theoretically analysed by first principles. Experimental results showed the effect of CNTs on electro-optical properties of hybrid LCs depended on the groups contained in monomer LCs. LCs with polar groups at the end increased the dielectric anisotropy of the composite, while the impact of CNTs on hybrid LCs containing non-polar terminal monomers was the opposite. The same variation was reflected in splay elastic constants and clearing points. Meanwhile, dielectric anisotropy, splay elastic constant, and rotational viscosity coefficients all changed with CNTs doping concentrations, reflecting the order of binding stability between representative groups and CNTs, and the variation of threshold voltage and response time reflected the order of binding stability between LC molecules and CNTs, consistent with theoretical calculations. Conductivity tests showed the additive of CNTs increased the conductivity of the composite and revealed the impact of CNTs on threshold voltage. Dielectric tests showed the incorporation of CNTs increased dielectric real and imaginary parts in low-frequency regions and increased relaxation frequency in high-frequency regions.

Comparison of thermal conductivity of nanofluids with single-walled and multi-walled carbon nanotubes

The purpose of the present paper is to systematically study and compare the thermal conductivity of nanofluids based on water+surfactants, ethylene glycol, ethylene glycol+surfactants, and isopropyl alcohol with single-walled (SWCNT) and multi-walled carbon nanotubes (MWCNT). The weight concentration of carbon nanotubes varied from 0.01 to 1 %. In all cases, the excess of the thermal conductivity coefficient in the nanofluid with SWCNTs is significantly higher than with MWCNTs. However, it should be borne in mind that the volume concentrations of MWCNTs in this case are several times lower than those of SWCNTs. The maximum excess of thermal conductivity coefficient was registered in the nanofluids based on isopropyl alcohol and is over 50 % at a SWCNT weight concentration of only 0.2 %. The enhancement of the thermal conductivity coefficient is greater, the lower the thermal conductivity coefficient of based fluid. The effect of the surfactants on the thermal conductivity of nanofluids is discussed. The thermal conductivity coefficients of nanofluids based on ethylene glycol+surfactants are almost twice as high as those of nanofluids based on ethylene glycol. It is shown that at a fixed weight concentration, the thermal conductivity of nanofluids increases with a decrease in the nanotube length, but their volume concentration also increases in almost proportion to the length decreasing. Finally, the nanofluids with SWCNTs provide an excess of the thermal conductivity unattainable with the use of conventional spherical nanoparticles.

Dielectric and thermal properties of potassium nitrate–carbon nanotubes composites

The results of a study of composites obtained by mixing potassium nitrate and carbon nanotubes are discussed. It has been shown that the effects of the interaction of the composite components lead to the expansion of the temperature range of the existence of the ferroelectric phase of potassium nitrate from 22 K for KNO3 to 38 K for a composite with a carbon nanotubes content of 2.0 vol % percent.

Determination of carbon nanotubes concentration by tabletop dynamic susceptometer.

Carbon nanotubes (CNTs) can be incorporated in various materials to enhance their mechanical or electrical properties. Information on their precise concentration and local distribution is difficult to access non-invasively. For example, electron microscopy studies require cutting of samples. Another way to measure the concentration of CNTs is by the magnetic susceptibility of the ferrocene present in the CNTs by the synthesis process, which can be performed on sample coupons on a vibrating sample magnetometer (VSM); VSM is a bulky laboratory instrument, and the size of the samples studied is constrained. In order to provide a technique that is fast, easy, cheap, and adaptable to the size of the samples, we have developed a benchtop device that measures the CNT concentration through an original inductive dynamic measurement of the ferrocene magnetic susceptibility. We present the method for extracting CNT concentrations and show the results obtained on cement matrices with CNT concentrations of the order of a few percent.

Analysis of Acid Diffusion Effects on Physical Properties of Polymer Composites: A Combined Study of Mechanical and Electrical Characterization

In this study, we examined the impact of carbon nanotube (CNT) concentration on the mechanical properties of epoxy/CNT composites under acid exposure. Samples with varying CNT concentrations (0% to 5%) were fabricated and characterized using dynamic mechanical analysis (DMA) and nanoindentation. Beyond the percolation threshold, the composites experienced decreased bulk mechanical properties due to CNT agglomeration. Acid exposure for one week and one month revealed a gradient of properties from the sample’s skin to its core. Overall, the composites exhibited modified physical properties, with degradation influenced by the CNT concentration. Higher concentrations acted as barriers but also created pathways for acid diffusion through pores surrounding CNT agglomerates. The agreement between nanoindentation and vector network analyzer (VNA) measurements further supported our findings. This convergence of mechanical and electromagnetic characterization techniques holds promise for wireless structural health monitoring (SHM) applications. Our study enhances the understanding of epoxy/CNT composites for SHM applications. The relationship between CNT concentration, acid exposure, and mechanical properties guides material selection and the development of real-time damage-detection techniques. Integrating multiple measurement techniques, as demonstrated by the agreement between nanoindentation and VNA data, provides a comprehensive understanding of structural behavior, improving SHM practices.

Strong synergistic toughening and compatibilization enhancement of carbon nanotubes and multi-functional epoxy compatibilizer in high toughened polylactic acid (PLA)/poly (butylene adipate-co-terephthalate) (PBAT) blends

Different carbon nanotubes (CNTs) contents on high-toughness polylactic acid (PLA)/poly (butylene adipate-co-terephthalate) (PBAT) blends were prepared by one-step melt blending using multifunctional epoxy oligomers (ADR) as reactive compatibilizer. During reactive blending, the PLA or PBAT chains were grafted onto the CNTs by allowing the carboxyl or hydroxyl groups to react with epoxy groups and form a branched CNTs-based copolymer. The branched copolymer at the interface between PLA and PBAT was dispersed through emulsion to improve the polymer–polymer or polymer–nanoparticle entanglement between the molecular chains. Interfacial adhesion, interface layer stability, and system viscoelasticity and compatibility were improved as indicated by rheological curves and dynamic mechanical analysis. The strength and toughness of the sample were simultaneously improved by the addition of CNTs and ADR. The impact strength reached 35.3 kJ/m2, which was approximately 7 times that of the PLA/PBAT blend, and the tensile strength was also increased from 33.6 MPa to 42.8 MPa. The properties of PLA/PBAT blend synergistically modified by ADR and CNTs were obviously better than those of PLA/PBAT blend modified by ADR or CNTs. The toughening synergistic effect of ADR and CNTs on PLA/PBAT was observed with efficiency reaching 3.05. With the further understanding of the toughening mechanism, the branched CNTs-based copolymers and CNTs clusters induce a synergistic effect, which increased the interfacial adhesion and ability of energy dissipation and stress transmission.

Efficient regeneration of shoots and roots in graphene oxide and carbon nanotubes mediated callus cultures: A qualitative and quantitative study

The applications of nanomaterials have been assessed for the regeneration of plants and secondary metabolite content. The purpose of this study was to investigate the effects of carbon nanotubes and reduced graphene oxide nanosheets on callus cultures of Fagonia indica. We aimed to assess for the first time whether reduced graphene oxide and carbon nanotubes causes plant regeneration in the absence of plant growth regulators. The callus cultures of Fagonia indica were grown in Murashige and Skoog media enriched with different concentrations of nanomaterials to examine their effect on its regeneration, biomass accumulation, and phytochemical content. Morphological and biochemical responses are measured upon interaction with nanomaterials at different time periods. Results show that calli treated with the highest concentration of carbon nanotubes showed regeneration, while the media containing reduced graphene oxide induces regeneration of shoots and roots at all concentrations. Moreover, the callus growth and biomass accumulation were increased upon addition of both nanomaterials, but the significant results are obtained at low concentration (1 mg/L and 2 mg/L). The media containing carbon nanotubes at a concentration of 2 mg/L produced the maximum biomass yield (FW= 0.7914 g, DW= 0.067 g), whereas the media containing reduced graphene oxide at a concentration of 1 mg/L produced the lowest yield (FW= 6.02985 g, DW= 0.3405 g). The highest total phenolic and flavonoid content values are obtained at the highest concentration of nanomaterials. However, the callus treated with reduced graphene oxide showed increased total phenolic content (107.4 µg GAE/mL) and total flavonoid content (8.06 µg QE/mL) as compared to total phenolic content (32.3 µg GAE/mL) and total flavonoid content (7.11 µg Q/mL) observed in callus treated with carbon nanotubes. Further, the data from High-Performance Liquid Chromatography shows that carbon nanotubes alone have the potential to trigger the pathways of secondary metabolism while reduced graphene oxide triggers only the production of Quercetin and Gallic acid. This study gives the first evidence that the use of reduced graphene oxide gives better results than carbon nanotubes as an elicitor for inducing plant regeneration, biomass accumulation, and the in vitro biosynthesis of valuable secondary metabolites.

Study on the effect of carbon nanotubes on the properties of wasted engine oil recycled asphalt binder

A large amount of reclaimed asphalt pavement mixture (RAP) is produced in the process of pavement maintenance. By mixing RAP, wasted engine oil regenerant, new asphalt binder and new aggregate in a certain proportion, recycled asphalt mixture can be produced. This saves a lot of resources and costs, but the wasted engine oil recycled asphalt binder (RAS) has problems such as instability, easy aging and decreased adhesion. In this paper, carbon nanotubes were used to modify RAS. We find that carbon nanotubes can improve the softening point, ductility and viscosity of RAS. In addition, the thermogravimetry (TGA) test results show that carbon nanotubes can significantly improve the thermal stability of RAS. The initial decomposition temperature of RAS containing carbon nanotubes can reach 336.84℃, which is 11.84℃ higher than that of the RAS. At the same time, the decomposition temperature of the lightweight component is significantly increased by 17℃ compared to the pristine asphalt binder. The results of UV aging experiment show that carbon nanotubes can effectively delay the UV aging process of RAS. The results of mechanical drawing test and ultrasonic boiling test confirm that carbon nanotube improves the adhesion property between the RAS and the aggregate, and then improves the water damage resistance of the RAS. The adhesion of RAS improves significantly when the carbon nanotubes content is 1.5wt%. In general, carbon nanotubes have a good application potential to improve the performance of RAS.

Investigation of the electrical sensing properties of cementitious composites produced with multi-wall carbon nanotubes dispersed in NaOH

The use of nanomaterials, such as carbon nanotubes, in cement-based composites has been a topic of considerable attention in recent years due to their potential to monitor civil structures and infrastructures. One of the main challenges is the adequate and efficient dispersion of the carbon nanotubes due to their nanoparticle size and the high adhesion forces developing among them. The most common strategy to tackle this challenge is to use sonic treatments that are unfeasible for field-scale implementations. Alternatively, specific chemicals (i.e. surfactants) facilitating nanotube mixing are used, but this often results in poor mechanical properties, reduced electrical conductivity and high environmental impact of the composites. This works has as the main aim to analyze the self-sensing properties of the cementitious composites developed with NaOH as the dispersing agent. For this purpose, the work investigates electrical and sensing properties of cement-based nanocomposites with different contents of multi-wall carbon nanotubes (MWCNT), namely 1%, 1.5%, and 2% with respect to cement weight, previously dispersed in NaOH aqueous solution. The composites' fresh and electrical properties are evaluated, and a microstructural analysis is carried out. The major findings of the work reveal that cement paste samples with different contents of MWCNT presented increasing sensing properties up to 2%, and that the dispersing strategy was promising despite its simplicity.