CNTs Content Research Articles

Self-healing Ability of Epoxy Vitrimer Nanocomposites Containing Bio-Based Curing Agents and Carbon Nanotubes for Corrosion Protection

Epoxy is extensively used for anti-corrosion coatings on metallic materials. Conventional epoxy coatings have a permanent crosslink network that is unable to repair itself when cracks and damages occur on the coating layer. This study aims to develop self-healing epoxy vitrimer/carbon nanotube (CNTs) nanocomposite for coating. Two bio-based curing agents viz., cashew nut shell liquid (CNSL) and citric acid (CA) were employed to create covalent adaptable networks. The 0–0.5 wt% CNTs were also incorporated into epoxy/CNSL/CA matrix (V-CNT0-0.5). Based on the results of our study, thermomechanical properties of V-CNT nanocomposites increased with increasing CNTs content. The bond exchange reaction of esterification was thermally activated by near infrared (NIR) light. The V-CNT0.5 showed the highest self-healing efficiency in Shore D hardness of 97.34%. The corrosion resistance of coated steel with V-CNT0 and V-CNT0.5 were observed after immersing the samples in 3.5 wt% NaCl for 7 days. The corrosion rate of coated steel with V-CNT0.5 decreased from 9.53 × 102 MPY to 3.12 × 10–5 MPY whereas an increase in protection efficiency of 99.99% was observed. By taking advantages of the superior self-healing and anti-corrosion properties, V-CNT0.5 could prove to be a desirable organic anti-corrosion coating material.

Boosted hydrogen evolution activity from Sr doped ZnO/CNTs nanocomposite as visible light driven photocatalyst

CNTs were decorated onto Sr doped ZnO nanoparticles to construct an efficient photocatalyst via a facile sol-gel method. The as-fabricated Sr doped ZnO/CNTs with recyclability exhibits Sr and CNTs content dependent hydrogen evolution activit under visible light illumination. The Sr doped ZnO/CNTs photocatalyst shows the highest hydrogen evolution rate of 2732.2 μmolh−1g−1, which is 33.7 and 2.83 times higher than pure ZnO and Sr doped ZnO photocatalysts, respectively. The improved hydrogen evolution activity of Sr doped ZnO/CNTs is primarily assigned to high surface area, Sr doping and construction of heterojunction, which can extend the light absorption, decrease the optical band gap and improve the charge separation. Moreover, the underlying photocatalytic mechanism is proposed on the basis of Mott-Schottky study and explains the interfacial charge transfer process from ZnO to CNTs and Sr. This work open new strategies to synthesize CNTs based nanocomposite for hydrogen evolution.

The Network Structure Formation of Cu-CNTs Composites During Multi-Directional Forging Process and its Mechanical Properties

Cu–[Formula: see text] CNTs composites ([Formula: see text], 1, 2, 3 vol.%) were successfully prepared using a combination of pre-treatment, powder metallurgy and multi-directional forging processes, which provides a solution for the industrial manufacture of the composites with network CNTs structures. During the multi-directional forging process, the CNTs in the composites were distributed in a network under the synergy of metal flow and copper particle squeeze. Compared with other structure modes, the network CNTs can effectively carry and transfer loads resulting in the promotion of mechanical properties (such as, the tensile strength approximately 1.5 times higher than those of composites with the same volume fraction without network structure). The composite with 2 vol.% CNTs had the highest elongation in this experiment (41%), which is about 5 times higher than the composites with other CNTs distribution patterns. At a low CNTs content level (1[Formula: see text]vol.%), a complete load transfer network cannot be formed, resulting in a relatively insufficient mechanical properties of the composites. As the content level is exceeded (3vol.%), it caused significant agglomeration of the CNTs, which lead to fracture in the agglomerated CNTs and elongation degradation of the composites.

Rheological, Dynamic and Tensile Mechanical Properties of Recycled Styrofoam Loaded with Carbon Nanotubes

Styrofoam was recycled and then loaded with different volume fractions of multiwalled carbon nanotubes (MWC-NTs). The frequency dependence of complex viscosity η*, storage modulus E/ and loss modulus E// were studied. All of them were increased with increasing MWCNTs concentration. The dependence of the complex viscosity on CNTs concentration was found to obey the rheological percolation behavior with low percolation threshold and depends on frequency. The addition of MWCNTs to recycled Styrofoam did not change the glass transition temperature. The tensile properties of all composites were studied at different temperatures. Stress-strain curves at temperatures 30, 50, 70 and 90 °C showed brittle behavior. The elastic modulus, ultimate strength, strain at break, and energy density to break were increased with increasing both CNTs concentration and temperature up to 90 °C. The elastic modulus had a tensile percolation behavior with a threshold value close to that obtained for η*. Plastic deformation of all composites took place at 105 °C and sharp decrease in both E and σb was observed. Conversely, sharp increase in both strain at break and energy density to break was observed at temperature 105 °C. The material at this temperature was converted from polydomain to monodomain configuration.

ADVANCE STUDIES ON MICROPROPAGATION OF DATE PALM.

Date palm is one of the most important fruit crops in the present and past, as the cultivated areas increase due to its high economics and grown in most lands and its tolerance to difficult conditions and therefore the demand for its offshoots was abundant. This study aimed to micropropagate date palm cultivar Amri through direct organogenesis, improving the growth of plantlets and establish a protocol for photoautotrophic and photomixotrophic as a new micropropagation system in order to obtain highest success percentage and lowest the loss percentage in the acclimatized plantlets during the acclimatization stage, this was done by performing two main experimental groups In-vitro and Ex-vitro Where the effect of different concentrations of auxins, cytokinins and AC. during the direct organogenesis stage was studied, as well as the study of some substances affecting the growth and improvement of plants during the elongation and rooting stages, such as the use of different concentrations of CNTs, spirulina platensis algae extract and Kafom-Cu, PEG and SiO2 and Kafom-Mg. The effect of ventilation rates in cultivation vessels with different concentrations of sucrose in the rooting medium and under CO2 enriched conditions (photoautotrophic and photomixtrophic) or under normal conditions for micro-propagation in the in vitro during the rooting and pre-acclimatization stages in addition to the acclimatization stage were studied in which different systems were studied. For greenhouse cultivation, it also affects different alcohol sugar concentrations of sorbitol and salicylic acid concentrations. Anatomical and chemical studies were also conducted on the best treatments during the rooting and pre-acclimatization stages. The following results were obtained: Adding 0.2 mg l-1 2,4-D + 0.12 mg l-1 NAA + 0.12 mg l-1 IAA + 0.1 mg l-1 2iP + 0.15 mg l-1 BA + 0.5 g l-1 AC to the cultivation medium encouraged the formation of direct shoots. While planting the plants on a medium containing MS added to 20 mg l-1 of spirulina extract increased the length of the shoots, the addition of K-Mg at 1.2 mg l-1 to the rooting medium achieved the highest values ​​of vegetative growth parameters and root system, with the plantlets and media free from contamination. Addition of SiO2 at 20 mg l-1 improved the trunk thickness. It also showed the use of the rate of ventilation 4 holes in the planting pot + 15 g l-1 of sucrose added to the rooting medium under the conditions of enriched with CO2 at 1500 ppm achieved the highest growth vigor and the highest percentage of survival and increased the content of the leaves of amino acids and reducing sugars and their content of Chlorophyll a + b. cultivation plantlets in mixture of Peat moss with Perlite (1: 1 v / v) plus 3 g/pot Barbary-Plante with foliar spray and watered by sorbitol at 30 g l-1 plus salicylic acid at 40 mg l-1 gave the highest values ​​for survival percentage, leaf width and growth vigor (91%, 2.73 cm, 4 respectively).

Scalable manufactured bio-based polymer nanocomposite with instantaneous near-infrared light-actuated targeted shape memory and remote-controlled accurate self-healing

Remote control and targeted activation are the elevated goals for shape-memory and self-healing polymers when responses to stimuli. Among so many stimuli, converting light into microstructure change or mechanical motions is now of particular interest. Herein, we report the ingenious design, synthesis and operation to advanced materials that capable of fast near-infrared (NIR) light-actuated targeted shape memory and remote accurately self-healing. Starting from biomass resources, a well-defined polymer nanocomposite, CNTs-graft-poly(tetrahydrofurfury methacryla-co-lauryl acrylate-co-1-vinylimidazole) copolymer ((CNTs-g-P(TMA-co-LA-co-VI)), was fabricated by addition-fragmentation chain transfer (RAFT) polymerization. After subsequent metal-ligand crosslinking with Zn2+ ion, CNTs-g-P(TMA-co-LA-co-VI)/Zn2+ with CNTs content of 1.1 wt % have a maximum stress of 1.68 MPa and an elongation at break of 450%. Most importantly, the photothermal conversion of CNTs can effectively trigger the association and dissociation process of the dynamic metallosupramolecular crosslinked bond between VI and Zn2+, leading to excellent instantaneous multiple shape memory and accurate self-healing performance under NIR light or heat. This approach can be generalized toward de novo design of self-healing and shape memory nanocomposites with tunable mechanical properties.

Role of Well-Dispersed Carbon Nanotubes and Limited Matrix Degradation on Tribological Properties of Flame-Sprayed PEEK Nanocomposite Coatings

Abstract High-performance carbon nanotubes reinforced polyether ether ketone (CNTs/PEEK) nanocomposites display an excellent combination of mechanical, thermal, and tribological properties. It is a challenge to deposit high-performance CNTs/PEEK nanocomposite coatings via the coating techniques based on solution or melting processes due to low solubility and high melting point of PEEK for tribological applications. In this work, the CNTs/PEEK nanocomposite coatings with CNTs contents of 0.1, 0.5, 1.0, and 2.0 wt% were prepared by flame spraying of mixed PEEK and CNTs powders using mechanical blending (MB) and ultrasound dispersion (UD) methods. The flame-sprayed CNTs/PEEK nanocomposite coatings using UD powders preserved good CNTs dispersion, low porosity, and surface roughness, adhesive coating–substrate interfaces. The thermal degradation of PEEK ascribed to overheating of in-flight particles and flame-rescanning coatings was limited by good CNTs dispersion in flame-sprayed CNTs/PEEK nanocomposite coatings with an increase of CNT contents. The good dispersion of CNTs aided in initiating crystallization and confined crystalline growth resulting in high crystallinity degree and small crystallite size of PEEK matrix in the flame-sprayed CNTs/PEEK nanocomposite coatings. The uniform nanocomposite coatings with well-dispersed CNTs and few PEEK degradation in optimum content of 1.0 wt% preserved enhanced microhardness and superiorly tribological properties. The well-dispersed CNTs bonding with PEEK matrix enhanced the mechanical strength to restrict the generation of fatigue cracks from defects of voids, which promoted self-lubrication and wear resistance of flame-sprayed CNTs/PEEK nanocomposite coatings.

Development of environmentally friendly inkjet printable carbon nanotube‐based conductive ink for flexible sensors: effects of concentration and functionalization

The fabrication of environmentally friendly printed flexible sensors is still an emerging technology, but with vast potential applications. Among the available printing techniques, inkjet printing is considered as a promising technique for flexible electronics because it enables high volume and versatile manufacturing, at low environmental impact. This study demonstrates a simple and facile method of preparing an environmentally benign water-based conductive ink, by dispersing functionalized and non-functionalized multi-walled carbon nanotubes (MWCNTs) in aqueous solution with the help of a biopolymer surfactant. The concentration of CNTs in the ink formulation was varied from 0.25 to 0.75 wt%, and additives such as triton-x 100, polypropylene glycol, and defoamer were added to achieve desirable ink properties. Inkjet printable ink was produced, and it was observed that the conductivity of the printed pattern is dependent on the printing pass. In addition, it was found that as the number of printing layer increases, there is higher synergy between concentration and number of printing pass in F-MWCNTs printed ink to produce higher electrical conductivity, compared to MWCNTs printed ink. Generally, the findings of this study could potentially open opportunities for global economic growth through the applications of printed, low cost and environmentally friendly flexible sensors.

Microwave‐Assisted Confining Flame‐Retardant Polypropylene in Carbon Nanotube Conductive Networks for Improved Electromagnetic Interference Shielding and Flame Retardation

Electrical conductive polymer composites (CPCs) with segregated structure can achieve better electrical conductivity with low content of conductive filler. Nevertheless, the undesirable properties of these CPCs, such as ease of burning, high smoke generation, weak interfacial adhesion, and poor mechanical performance, have restricted their practical applications. Herein, a promising microwave‐assisted strategy is developed for the fabrication of a flame‐retardant and electrically conductive polypropylene/ammonium polyphosphate/carbon nanotube (PP/APP/CNT) composite. Highly conductive networks can be set via the microwave‐selective heating, which results in an electromagnetic shielding effectiveness (EMI SE) of 32.1 dB of the composite with 7 wt% content of CNTs. Furthermore, the conductive segregated CNT network also serves as an excellent char‐forming agent to enhance the nonflammability and overcome the melt dripping issue of the pure PP matrix. As a result, the segregated conductive PP composites with 7 wt% CNTs and 15 wt% APP exhibit melt dripping and prompt self‐extinguishment, achieving the V‐0 rating level in the UL‐94 test. In brief, the well‐defined microwave‐assisted process provides a promising approach to fabricate various CPCs with simultaneously improved EMI shielding and flame‐retarding properties.

Investigating the Hall-Petch Constants for As-Cast and Aged AZ61/CNTs Metal Matrix Composites and Their Role on Superposition Law Exponent

AZ61/carbon nanotubes (CNTs) (0, 0.1, 0.5, and 1 wt.%) composites were successfully fabricated by using the stir-casting method. Hall–Petch relationship and superposition of different strengthening mechanisms were analyzed for aged and as-cast AZ61/CNTs composites. Aged composites showed higher frictional stress (108.81 MPa) than that of as-cast (31.56 Mpa) composites when the grain size was fitted directly against the experimentally measured yield strength. In contrast, considering the superposition of all contributing strengthening mechanisms, the Hall–Petch constants contributed by only grain-size strengthening were found (σ0 = 100.06 Mpa and Kf = 0.3048 Mpa m1/2) for as-cast and (σ0 = 87.154 Mpa and Kf = 0.3407 Mpa m1/2) for aged composites when superposition law exponent is unity. The dislocation density for the as-cast composites was maximum (8.3239 × 1013 m−2) in the case of the AZ61/0.5 wt.%CNT composite, and for aged composites, it increased with the increase in CNTs concentration and reached the maximum value (1.0518 × 1014 m−2) in the case of the AZ61/1 wt.%CNT composite.

Investigation of the Effects of Multi-Wall and Single-Wall Carbon Nanotubes Concentration on the Properties of ABS Nanocomposites

The effects of two types of carbon nanotubes, namely multiwall (MWCNT) and single-wall (SWCNT) carbon nanotube, on the thermal and mechanical properties of acrylonitrile-butadiene-styrene (ABS) nanocomposites, have been investigated. ABS filled-CNT nanocomposites with various filler loadings of 5–10 wt% were properly produced by a solvent-free process in blend compounding at 190 °C. Compression moulded plates and extruded filaments were obtained at 190 °C and 230 °C, respectively. Melt flow index (MFI), shore hardness, Vicat temperature, differential scanning calorimeter (DSC) and thermogravimetric analysis (TGA) were performed to characterize and compared the different CNT nanocomposites. ABS/SWCNT composite filaments showed higher tensile properties (i.e., stiffness and strength), than ABS/MWCNT. The electrical resistivity of ABS/SWCNT and ABS/MWCNT filaments decreased to 0.19 Ω.cm and 0.65 Ω.cm for nanocomposites with 10 wt% of nanofillers; a power law was presented to describe the electrical resistivity of composites as a function of the CNTs content. A final comparative parameter regarding melt flow, stiffness and conductivity was also evaluated for understanding the combined effects of the nanofillers. SWCNT nanocomposites exhibited better overall cumulative results than MWCNT nanocomposites.

Highly stretchable and self-foaming polyurethane composite skeleton with thermally tunable microwave absorption properties

Stretchable and lightweight polymer composite material possessing tunable microwave absorption (MA) properties under thermal radiations remain a significant challenge. Here, we proposed a facile strategy to fabricate stretchable, magnetic composite skeletons by incorporating the tadpole-like CNTs@Fe3O4 nanoparticles into self-foaming polyurethane (PU) matrix and the electromagnetic responsive of CNTs@Fe3O4/PU composite foams with different CNTs contents under heating−cooling cycle in a temperature range of 253 −333 K were carefully investigated. Enhanced complex permittivity and shifting peak frequency were observed at elevated temperatures. For instance, the 70-CNTs@Fe3O4/PU sample with 15 wt% loading content at 333 K exhibits excellent MA properties including a minimum reflection loss (RLm) of −66.9 dB and ultrabroad effective frequency bandwidth (RL ≤ −20 dB) of 9.98 GHz at the thickness of 1.58−3.37 mm. Meanwhile, great recoverability in terms of RL-f profile was achieved in the process of thermal cooling back to 253 K. Such adjustable MA property was attributed to the well-matched impedance and dramatic attenuation ability, benefiting from the temperature-dependant electrical conductivity, abundant interfacial polarization and interior microcellular structures. Besides, the rising temperature increased the sample elongation and electrical conductivity with a slight sacrifice of maximum tensile strength. This stretchable PU skeleton with a unique assembly of CNTs and Fe3O4 nanoparticles are expected to be promising candidates as smart absorbers for application in the harsh environments.

Free vibration and buckling analyses of FG porous sandwich curved microbeams in thermal environment under magnetic field based on modified couple stress theory

Porous sandwich structures include different numbers of layers and are capable of demonstrating higher values of strength to weight ratio in comparison with traditional sandwich structures. Free vibration and mechanical buckling responses of a three-layered curved microbeam was investigated under the Lorentz magnetic load in the current study. A viscoelastic substrate was considered and the effect of the thermal environment on its mechanical properties was assessed. The core was composed of the functionally graded porous materials whose properties changed across the thickness based on some given functions. The face sheets were FG-carbon nanotube-reinforced composites and the influence of the placement of CNTs was evaluated on the behavior of the faces. Using the extended rule of mixture, their effective properties were determined. Modified couple stress theory was used to predict the results in the micro-dimension. While the governing equations were derived based on the higher order shear deformation theory and energy method, and mathematically solved via Navier’s method. The results were validated with the previously published works, considering the effects of various parameters. As comprehensively explained in the results section, natural frequencies and critical buckling loads were reduced by enhancing the central opening angle. Moreover, an increase in the porosity coefficient declined the mentioned values, but increasing the CNTs content showed the opposite effect. The outcomes of this study may help in the design and manufacturing of various equipment using such smart structures, making high stiffness to weight ratios more accessible.

ИССЛЕДОВАНИЕ ВЛИЯНИЯ НЕКОВАЛЕНТНЫХ МОДИФИКАТОРОВ НА СТРУКТУРУ И СВОЙСТВА ПОЛИМЕРНЫХ ФИЛАМЕНТОВ ДЛЯ FDM-ПЕЧАТИ НА ОСНОВЕ АБС-ПЛАСТИКА И УГЛЕРОДНЫХ НАНОЧАСТИЦ

The paper presents the results of a study of the effect of non-covalent modifiers on the structure and properties of polymer filaments for FDM-printing based on ABS-plastic and carbon nanoparticles. The dependences of the characteristics of nanocomposites and filaments based on them to the type of functionalization have been established. The effect of the concentration of CNTs on the hardness, water absorption, electrical resistance, and shear strength for modified polymer filament has been investigated. The optimal formulations and technological parameters of FDM-printing of templates have been determined.

Studying Changes in the Electrical Resistance of Elastomers Modified by Carbon Nanotubes during Their Compression, Stretching, and Torsion

Developing “smart” materials with improvement of both structural and functional characteristics is one of the promising areas of materials science. Measuring the electrical resistance of CNT-modified (various mass contents) polymers and, in particular, elastomers when performing several tests (compression, stretching, and torsion) at a constant current is relevant in electrical engineering, mechanical engineering, and the aerospace industry. Changes in the elastomer shape under different types of testing lead to the destruction of macromolecules and the structuring of the material as a whole. Therefore, it is important to study the effect of CNT-based modifying fillers on the elastomer. When compressing, stretching, or twisting the nanomodified elastomer, along with the mutual movement of its macromolecular fragments and aggregates, the modifier particles also move, which generally determines the transport of electrons in the resulting structure and affects the physical and mechanical parameters of the composite material. To conduct studies, elastomers containing different amounts of a CNT-based modifying filler were prepared. To investigate and elucidate the relevant dependences, a measuring system (MS) making it possible to determine the values of electrical resistance of the composite material with different contents of CNTs in the polymer matrix composition exposed to various mechanical loads was constructed. On the basis of the results, it was established that the electrical resistance of the elastomer composites modified with 1.0–2.5 wt % CNTs decreases upon compression from 0 to 100 N, whereas when the compression force ranges from 100 to 350 N, the electrical resistance remains unchanged. When the elastomer composites modified with 2–2.5 wt % CNTs were stretched by 30–40%, the electrical resistance was found to increase from 5 × 103 to 1.9 × 107 Ω.

Electric Heating Behavior of Reduced Oxide Graphene/Carbon Nanotube/Natural Rubber Composites with Macro-Porous Structure and Segregated Filler Network.

Conductive polymer composites with carbonaceous fillers are very attractive and play a significant role in the field of electric heaters owing to their lightweight, corrosion resistance, and easy processing as well as low manufacturing cost. In this study, lightweight reduced oxide graphene/carbon nanotube/natural rubber (rGO/CNT/NR) composites were fabricated by a facile and cost-effective approach, which consists of rGO assembling on rubber latex particles and hydrogels formation due to the interaction network established between carbonaceous fillers and subsequent mild-drying of the resulting hydrogels. Thanks to the amphiphilic nature of GO sheets, which can serve as a surfactant, the hydrophobic CNTs were easily dispersed into water under ultrasound. On the basis of both the high stable rGO and CNTs suspension and the assembling of rGO on rubber latex, a three-dimensional segregated network of CNT and rGO were easily constructed in macro-porous composites. Either the segregated network and macro-porous structure endowed the resulting composites with low density (0.45 g cm−3), high electrical conductivity (0.60 S m−1), and excellent electric heating behavior, when the weight content of rGO and CNTs are 0.5% and 2.5%, respectively. For electric heating behavior, the steady-state temperature of the above composites reaches 69.1 °C at an input voltage of 15 V.

Influence of acid-treated time of carbon nanotubes on mechanical property in carbon nanotubes reinforced copper matrix composites

Carbon nanotubes reinforced copper matrix (CNT/Cu) composites with high mechanical properties were successfully fabricated by wet mixing and spark plasma sintering (SPS). The effects of CNTs acidification time and CNTs content on the microstructure and mechanical properties of composites were characterized by SEM, FTIR, Raman, HR-TEM and tensile tests. The composites with 24 h acid-treated CNTs (0.5 wt%) and sintered at 837 K had the most optimal mechanical properties, which primarily stemmed from the use of oxygen as an atomic transient agent to form solid Cu-CNT interfacial bonding, the complete densification of the composites and the uniform dispersion of the CNTs. From the density functional calculations, the strong contact mode of Cu2O-CNT is conducive to the improvement of mechanical properties. In addition, the reinforcing effect of surface modification at different acidification times of CNTs was studied and discussed by the strengthening models. This study describes an approach for uniformly dispersing CNTs to enhance the mechanical properties of CNT/Cu composite materials with strong interface bonding and enhancement.

Effect of carbon nanotubes content on microstructure and properties of WC/Ni laser cladding coatings

ABSTRACT To enhance the mechanical properties of Ni–WC coatings, the carbon nanotubes were used as reinforced materials by laser cladding. Optical microscopy (OM), scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) were used to investigate the effect of CNTs content on the phase composition and microstructure. The microhardness and wear resistance were measured by Vickers hardness testing and friction wear testing. Experimental results showed that the new phases Cr2Fe14C are found in the coatings with CNTs, the grain size is finer than that of the coating without CNTs. The microhardness and wear resistance of the coatings with CNTs content ranging from 0 to 5 wt-% present increase initially and then decrease trend. The coatings with 3 wt-% CNTs have the highest microhardness and wear resistance, which proved that the appropriate amount of CNTs addition is 3 wt-%.

Performance and cost analysis of photovoltaic thermal (PVT)-compound parabolic concentrator (CPC) collector integrated solar still using CNT-water based nanofluids

In present research article, analytical analysis has been performed to inspect the performance and thermo-physical characteristics of partially covered series connected N- photovoltaic thermal (PVT)-compound parabolic concentrator (CPC) collectors integrated double slope solar still coupled with helically coiled heat exchanger (HE) incorporating single wall carbon nanotubes (SWCNT) and multiwall carbon nanotubes (MWCNT)- water based nanofluid. Temperature, heat transfer coefficients (HCTs), and Nusselt number in different section; and thermal energy/exergy, and productivity - of the proposed system have been investigated in detail for 1% concentration of CNTs; 25 kg basin fluid (BF/NF) mass, 0.03 kg/s mass flow rate (optimized), and four number of PVT-CPC collectors (optimized) for hot weather conditions of New Delhi. Enhancement around 46.4%, 46.7%, 76.7% in HTCs of PVT-CPC collector, helically coiled aluminum HE and DSSS section respectively have been observed for SWCNT-water based nanofluid. Percentage enhancement in total yield obtained using SWCNT and MWCNT is found to be 65.7% and 28.1% respectively. From the cost analysis, the production cost Cp (Rs. /litre) of daily yield obtained from the system with SWCNT [0.975 (i = 4%),0.982 (i = 8%),and 1.028 (i = 10%)],and MWCNT [1.23 (i = 4%),1.24 (i = 8%),and 1.30 (i = 10%)] for n = 30 is found to be very nominal.

A Wet Chemical Synthesis and Characterization of Mwcnt-Starch Biocomposites

MWCNT/starch composites were prepared by simple solution casting method by incorporating upto 1.0 wt. % of multi-walled carbon nanotubes (MWCNTs) as reinforcing fillers in the starch matrix. Gelatin was used as dispersing agent to disperse the MWCNTs into aqueous solution and glycerol was used as plasticizer to form composites. SEM images of the MWCNT/starch composite show the homogenous surface of the composite where CNTs are embedded into the starch matrices. XRD spectra of the composite show no characteristic peaks of CNTs in the starch matrix. FTIR spectra show peaks at around 3435 and 2927 cm-1 indicating that the covalent bonds between –OH groups and C-H groups of soluble starch and CNT were formed in the composite. Electrical conductivity of the composite was enhanced from 2.85×10-9to 5.28× 10-8 S/m due to the addition of CNTs at room temperature and decreased with the increase of temperature. UV visible spectra showed increasing absorption with increasing CNTs content in the composite. TGA analysis demonstrated the stability of the MWCNT/starch composite.
 Journal of Bangladesh Academy of Sciences, Vol. 44, No. 1, 43-52, 2020