scholarly journals Model and mechanism of carbon nanotube stabilization with plasticizer

2018 ◽  
Vol 193 ◽  
pp. 03050 ◽  
Author(s):  
Svetlana Samchenko ◽  
Irina Kozlova ◽  
Оlga Zemskova
Keyword(s):  
Carbon Nanotube ◽  
Dispersion Medium ◽  
High Viscosity ◽  
Cement Stone ◽  
Ultrasonic Dispersion ◽  
Water Suspension ◽  
Nanoparticle Surface ◽  
Water Suspensions ◽  
Cement System ◽  
Electrical Layer

Mechanism of stabilization of carbon nanotube (CNT) water suspension with plasticizer based on sulfated naphthalene formaldehyde resins is proposed in this article. CNT stabilization is achieved at the expense of fixing plasticizer group on the nanoparticle surface. Nonpolar part of plasticizer provides the formation of high-viscosity streak between CNTs particles and dispersion medium, and polar part provides the formation of double electrical layer, that supports formation of CNT micelle. Model of carbon nanotube micelle is described. It is determined that the conducting of ultrasonic dispersion of CNTs water suspensions with plasticizer based on sulfated naphthalene formaldehyde resins provides stability of CNTs suspensions for 7 and more days. Optimal options of ultrasonic effect are identified. It is shown that CNT suspension stabilized with sulfated naphthalene formaldehyde evenly apportion in volume of cement system in conclusion of the adding them to composition of cement paste. This distribution helps with obtaining cement stone with high exploitative properties.

scholarly journals MODEL AND MECHANISM OF CARBON NANOTUBE STABILIZATION WITH PLASTICIZER BASED ON POLYCARBOXYLATE

Vestnik MGSU ◽  
2017 ◽  
pp. 724-732
Author(s):  
Svetlana Vasilevna Samchenko ◽  
Olga Viktorovna Zemskova ◽  
Irina Vasilevna Kozlova
Keyword(s):  
Portland Cement ◽  
High Viscosity ◽  
Matrix Composition ◽  
Cement Matrix ◽  
Cement Stone ◽  
Modern Theory ◽  
Ultrasonic Dispersion ◽  
Cement System ◽  
Electrical Layer ◽  
The Stability

The method for adding into the cement matrix composition the carbon nanotubes (CNTs) in the form of stabilized suspensions for their even allocation in its volume is observed in this article. The aim of the article is to study the aggregative and sedimentary stability of the CNTs suspensions in the presence of the plasticizer based on polycarboxylate under the ultrasonic effect, to determine the kinetic addictions of coagulation, to describe the suspension stabilization models and mechanisms according to the modern theory and to determine the possibility of using CNTs as suspensions for portland cement modification. The object of research is Portland cement, CNts and polycarboxylate-based plasticizer. Mechanism of stabilization of the CNT water suspension with polycarboxylate based plasticizer due to fixing plasticizer functional groups on the nanoparticle surface is proposed. The non-polar part of the plasticizer provides the formation of high-viscosity streak between the CNTs particles and the dispersion medium, and the polar part provides the formation of the double electrical layer (DEL), which supports the formation of the CNT micelle. The Model of the CNT micelle is described. It is established that the ultrasonic dispersion provides the stability of the CNTs suspensions for seven days and more. It is shown that when the stabilized polycarboxylate-based plasticizers of the CNT are introduced in the form of suspensions into the cement paste composition, they are evenly distributed in the volume of the cement system. This causes the production of cement stone with enhanced exploitative properties.

Model and Mechanism of Stabilization of Carbon Nanotubes with Placticizer on the Basis of Sulfonated Naphthalene Formaldehyde Resins

2018 ◽  
Vol 931 ◽  
pp. 481-488
Author(s):  
Svetlana V. Samchenko ◽  
Irina V. Kozlova ◽  
Olga V. Zemskova
Keyword(s):  
Aqueous Suspension ◽  
Double Electric Layer ◽  
High Viscosity ◽  
Polar Component ◽  
Cement Stone ◽  
Ultrasonic Dispersion ◽  
Aqueous Polymer ◽  
Nonpolar Component ◽  
Dispersion Media ◽  
The Stability

The entry presents studies of the effect of dispersion temperature on the deposition rate of CNTs in the presence of a plasticizer based on sulfonated naphthalene formaldehyde resins, on the dispersed composition of CNTs in aqueous and aqueous-polymer dispersion media and on the strength characteristics of samples with stabilized CNTs. It was established that the ultrasonic dispersion of aqueous suspensions of CNTs in the presence of a plasticizer based on sulfonated naphthalene formaldehyde resins at an ultrasonic vibration frequency of 44 kHz; dispersion temperature - 25 ± 2 °C; dispersion time - 10 - 30 minutes is capable of ensuring the stability of CNTs suspensions for 7 days or more. The mechanism of stabilization of aqueous suspension of CNTs by a plasticizer based on sulfonated naphthalene formaldehyde resins is presented. It has been established that the stabilization of CNTs is achieved by fixing the functional groups of the plasticizer on the surface of the nanoparticle, the nonpolar component of which ensures the formation of a high-viscosity interlayer between the CNTs particles and the dispersion medium, and the polar component is the formation of a double electric layer (DEL) that promotes the micellization of CNTs. As a result, the CNTs stabilized with sulfonaphthalene formaldehyde are evenly distributed in the volume of the cement system, causing the production of cement stone with enhanced performance properties.

Improvements on Mechanical Property and Microstructure of Cementitious Composite Incorporated with Silica Fume and Carbon Nanotube

2019 ◽  
Vol 298 ◽  
pp. 167-171
Author(s):  
Gu Yue Han ◽  
Jian Lin Luo
Keyword(s):  
Compressive Strength ◽  
Carbon Nanotube ◽  
Silica Fume ◽  
Cementitious Materials ◽  
Filler Loading ◽  
Cement Matrix ◽  
Ultrasonic Dispersion ◽  
Integrated Network ◽  
Positive Effects ◽  
Ultrafine Silica

Nano-size fillers (ultrafine silica fume (USF) or/and multi-walled carbon nanotube (MWCT)) were incorporated into cement matrix to fabricate nano-fillers reinforced cementitious materials (NFRCs) with surfactant ultrasonic dispersion and subsequently mix cast process. The flexural and compressive strengths of four groups NFRCs with varied nano-filler loading were comprehensively investigated. Results show, there are positive effects on the flexural and compressive strength of NFRCs with nano-fillers loading, especially when USF and MWCT are incorporated simultaneously, and the correspondent maximal flexural and compressive strength can increase by above 17%, 28% with respect to the baseline, respectively. The pozzolan infilling effect of USF and the crack-bridging effect of dispersed MWCT result in the dense and integrated network microstructures of cured NFRC.

scholarly journals Influence of optimal conditions of ultrasonic dispersion on the stability of suspensions of finely ground slags

2019 ◽  
Vol 265 ◽  
pp. 01017 ◽  
Author(s):  
Svetlana Samchenko ◽  
Irina Kozlova ◽  
Оlga Zemskova ◽  
Ekaterina Baskakova
Keyword(s):  
Aqueous Dispersion ◽  
Cement Composite ◽  
Cement Stone ◽  
Mechanical Mixing ◽  
Dispersion Parameters ◽  
Ultrasonic Dispersion ◽  
Sedimentation Stability ◽  
Granulated Blast Furnace Slag ◽  
The Stability ◽  
Furnace Slag

The preparation in the jet mill of finely ground slag (FGS) from the waste of metallurgical production granulated blast-furnace slag, the obtaining of slag suspensions, and the behavior of FGS particles in an aqueous dispersion medium are considered in the paper. It was found that FGS particles in the suspension form micelles of two types with negative (micelle 1) and positive (micelle 2) charges of FGS surface. To increase the aggregative and sedimentation stability of FGS particles in suspensions, studies were carried out using ultrasonic dispersion. The results of investigations on the detection of optimal dispersion parameters for slag suspensions are presented. It was found that in the absence of temperature control, the process of coagulation of slag particles is accelerated and aggregative and sedimentation stability of suspensions of FGS is reduced. The slag particles in the suspension form aggregates that lead to a deterioration of the strength characteristics of the cement stone using suspensions of FGS. Optimal parameters of ultrasonic dispersion of slag suspensions are established: the frequency of ultrasonic vibrations is equal to 44 kHz; the dispersion temperature is 25 ± 2 °C; the dispersion time is 15 min. It was found that the application of ultrasonic dispersion to slag suspensions with the observance of dispersion conditions can increase the aggregative and sedimentation stability of FGS suspension by 2-3 times in comparison with the mechanical mixing of suspensions. The strength of samples with suspensions of FGS prepared using UST under the recommended dispersing conditions increased by 19 to 39% in the first day; for 28 days of hardening - by 19 - 36%, which allows using slag suspensions in the production of cement composite materials and concretes based on them.

scholarly journals EFFECT OF MICROFILLERS BASED ON NATURAL WOLLASTONITE ON PROPERTIES OF FINE-GRAINED CONCRETE

2020 ◽  
pp. 20-28 ◽  
Author(s):  
E. Karpikov ◽  
N. Lukutcova ◽  
G. Soboleva ◽  
S. Golovin ◽  
Yu. Cherenkova
Keyword(s):  
Anionic Surfactant ◽  
Ball Mill ◽  
Bending Strength ◽  
Particle Diameter ◽  
Cement Stone ◽  
Particle Sizes ◽  
Ultrasonic Dispersion ◽  
Fine Grained ◽  
Amorphous Nature ◽  
Type C

The possibility of obtaining effective highly dispersed additives from natural wollastonite is substantiated and their influence on the properties of fine-grained concrete is investigated. On the basis of wollastonite, a complex micro-filler with particle sizes up to 100 microns was developed, obtained by joint grinding with quartz sand in a 3:1 ratio in a ball mill in the presence of an anionic surfactant naphthalene-formaldehyde type C-3 and a calcium stearate hydrophobizer technical C-17. A suspension of wollastonite with a modal particle diameter of 405 nm was obtained by pre-grinding wollastonite and anionic surfactant in a ball mill, with their further ultrasonic treatment in a bath-type activator. Mathematical models of the dependence of compression and bending strength on the content of the initial components are developed. It is established that the complex microfill leads to an increase in the strength of fine-grained concrete in bending by 2 times, in compression by 1.7 times with its content in the composition of fine-grained concrete in the amount of 10% by weight of cement. Wollastonite suspension increases the bending strength of fine-grained concrete to 3.1 MPa, compression to 57.8 MPa. The results of qualitative x-ray phase analysis showed that the total intensity of diffraction maxima of not fully hydrated alite C3S, belite C2S grains and their aggregates in cement stone with wollastonite decreases by 1.5-2 times compared to the control composition. This is most likely due to the amorphous nature of the wollastonite surface after grinding in a ball mill and ultrasonic dispersion in a bath-type activator. In addition, such particles are the centers of crystallization. Their needle-like shape contributes to the reinforcement of the structure by crystallizing new formations of cement stone.

scholarly journals Flexible Carbon Nanotube-Based Polymer Electrode for Long-Term Electrocardiographic Recording

Materials ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 971 ◽  
Author(s):  
Miao Chi ◽  
Jingjing Zhao ◽  
Ying Dong ◽  
Xiaohao Wang
Keyword(s):  
Carbon Nanotube ◽  
Weight Fraction ◽  
Superior Performance ◽  
Ecg Monitoring ◽  
Ultrasonic Dispersion ◽  
Contact Impedance ◽  
Uniform Dispersion ◽  
Long Term Monitoring ◽  
Term Monitoring

The long-term monitoring of electrocardiogram (ECG) is critical for the accurate diagnosis and tracking of cardiovascular diseases (CVDs). However, the commercial Ag/AgCl electrode is not suitable for long-term monitoring due to skin allergies and signal degradation, caused by the conductive gel drying over time. In this paper, a flexible gel-free electrode, composed of a multi-wall carbon nanotube (MWCNT) and polydimethylsiloxane (PDMS), is proposed for long-term wearable ECG monitoring. To achieve uniform dispersion of MWCNTs in viscous PDMS, we developed a novel parallel solvent-assisted ultrasonic dispersion method, wherein the organic solvent n–Hexane served as a dispersion to avoid MWCNT aggregates. The properties of the MWCNT/PDMS electrode were assessed through structural characterization, contact impedance tests, ECG measurements, and biocompatibility tests. When the MWCNT weight fraction reached 5.5 wt%, the skin-electrode contact impedance of the MWCNT/PDMS electrode was lower than that of the Ag/AgCl electrode below 100 Hz. In daily ECG monitoring, the MWCNT/PDMS electrodes showed superior performance against motion artifact compared to the Ag/AgCl electrode. After seven days of wearing the MWCNT/PDMS electrode, ECG signals did not degrade and no side effects, such as skin redness and swelling, were observed. Thus, this electrode could enable long-term ECG monitoring in wearable healthcare systems.

Properties of Cement with Photocatalytic Composite Material

2021 ◽  
Vol 1040 ◽  
pp. 153-158
Author(s):  
Yulia N. Ogurtsova ◽  
Valeria V. Strokova ◽  
Pei Qi Zhao ◽  
Marina V. Antonenko ◽  
Ekaterina N. Gubareva
Keyword(s):  
Composite Material ◽  
Cement Hydration ◽  
Sol Gel ◽  
Pozzolanic Reaction ◽  
Cement Stone ◽  
Stone Surface ◽  
Cement System ◽  
Self Cleaning ◽  
White Portland Cement

The paper presents the results of the determination of the effect of a photocatalytic composite material (PCM) with the composition SiO2‒TiO2 on the main properties of white Portland cement: heat release during hydration, phase composition and microstructural features of cement stone, pressure strength and self-cleaning ability. PCM was synthesized by a sol-gel method based on tetrabutoxytitanium and finely dispersed diatomite powder and 15% cement was added instead. The presence of PCM in the cement system provided the reduction of the induction period of cement hydration, consolidation of the microstructure of the cement stone with the products of the pozzolanic reaction, the ability to photocatalytic self-cleaning of the cement stone surface.

Temperature Sensitive Properties of Hybrid Carbon Nanotube/Carbon Fiber Cement-Based Materials

2013 ◽  
Vol 539 ◽  
pp. 89-93 ◽  
Author(s):  
Jun Jie Qin ◽  
Wu Yao ◽  
Jun Qing Zuo
Keyword(s):  
Activation Energy ◽  
Carbon Nanotube ◽  
Carbon Fiber ◽  
Temperature Sensitivity ◽  
Sensitivity Coefficient ◽  
Temperature Sensitive ◽  
Heating And Cooling ◽  
Cement Based Materials ◽  
Cement System ◽  
Hybrid Carbon

This paper gives an assessment on the temperature sensitive properties of hybrid carbon nanotube/carbon fiber cement-based materials. Different dosage of carbon nanotube (CNT) were added into a carbon fiber (CF) cement system to produce carbon nanotube-carbon fiber cement nanocomposites in the form of pastes. The temperature sensitivity coefficient, activation energy during heating and cooling, repeatability, linearity and electrical resistivity are tested. Results show that a high dosage of CNTs into cement paste can increase the temperature sensitivity coefficient, activation energy, repeatability and linearity, which has a vast potential for future development of temperature monitoring in concrete structures.

Effect of fungicides on infection of apricot and cherry pruning wounds inoculated with Chondrostereum purpureum

1983 ◽  
Vol 23 (120) ◽  
pp. 91 ◽  
Author(s):  
TJ Wicks ◽  
D Volle ◽  
TC Lee
Keyword(s):  
Polyvinyl Acetate ◽  
Water Suspension ◽  
Water Suspensions ◽  
Chondrostereum Purpureum

Wound protectants were evaluated on apricot and cherry by the inoculation of pruning wounds with-basidiospores of Chondrostereum purpureum within an hour of applying the protectant. Agseal (1% captafol and 1 % chinosol suspended in a polyvinyl acetate based paint) protected 100% of the cherry and 84% of the apricot wounds from infection and was more effective than a water suspension of 250 mg/litre captafol. Water suspensions of triadimefon at 25 mg/litre and oxycarboxin at 250 mg/litre were not effective, as greater than 70% of these treated wounds yielded the fungus. Neither Agseal nor 104 mg/litre of captafol was effective when applied 27 h after inoculation.Apricot and cherry wounds untreated or treated with Agseal at pruning were not infected by C. purpureum when inoculated more than 7 d after pruning.

The Effect of Surfactant and Alkali on the Surface Tension of Simulated Solutions of Alkali Activated Slag Cement System

2011 ◽  
Vol 399-401 ◽  
pp. 1246-1250
Author(s):  
Xian Feng Liu ◽  
Jia Hui Peng ◽  
Chang Hui Yang ◽  
Yu Yan Shu ◽  
Da Chang Wu
Keyword(s):  
Surface Tension ◽  
Water Glass ◽  
High Viscosity ◽  
Heat Of Hydration ◽  
Slag Cement ◽  
Alkali Activated Slag ◽  
Cement System ◽  
Cement And Concrete ◽  
Activated Slag ◽  
Alkali Activated

Alkali activated slag cement and concrete are high strength, rapid hardening, low heat of hydration, good durability and so on. Whereas, too high viscosity and bad workability of the fresh mixture is the crux of the matter to embarrass application of alkali-activated slag cement and concrete. Development of special superplasticizer for alkali activated slag cement and concrete is a worth exploring way to solve the problem, and the study on the surface tension of simulated solutions of alkali activated slag cement system is one of the basic researches about the special superplasticizer. In this paper, the surface tension of surfactant-alkali-water was studied by Wilhelmy method. The results showed, first, water-glass had the best efficacity of several alkali activators, when the modulus of water-glass was 1.5 and dosage of water-glass by Na2O was 8%, the surface tension was reduced by 33 mN/m and reduced to 39.9mN/m; second, [CH3(CH2)9]2N(CH3)2Cl had the best efficacity of several surfactants, when the concentration of [CH3(CH2)9]2N(CH3)2Cl was 50g/L, the surface tension was reduced by 35.3 mN/m and reduced to 32.5 mN/m; finally, the effect of surfactant and alkali together on the surface tension of water was complex, surfactants had hardly effective in water glass.

Sign in / Sign up

Export Citation Format

Share Document