Manufacturing Of Nanocomposites Research Articles

Scalable Manufacturing of Zinc-Tungsten Carbide Nanocomposites

Pure zinc (Zn) has a relatively low strength when compared to other metals. Tungsten Carbide (WC) has high melting point and mechanical properties. In this study, nanocomposite approach was investigated to improve Zn mechanical property by introducing WC nanoparticles. We show that the WC nanoparticle mixing with pure zinc by ultrasonic processing is facile and efficient for nanoparticles distribution and dispersion. Nanoparticles (4vol.%) were well dispersed in centimeter scale zinc matrix. Furthermore, the Zn–WC nanocomposites exhibited significantly higher mechanical properties (strength, ductility and hardness). Not only was the strength of the Zn-WC nanocomposites drastically increased but also its ductility. This unusual phenomenon can be attributed to the good dispersion and distribution of the WC nanoparticles within the Zn matrix. The approach presented here is highly promising for a scalable manufacturing of Zn-WC nanocomposites.

Study on microstructure and thermal properties of a CNF/Cu nanocomposite fabricated using chemical mixing

The microstructure and thermal properties of a carbon nanofiber reinforced copper matrix (CNF/Cu) nanocomposite processed by chemical mixing, with an electroless plated copper coating on the CNFs, were analyzed in depth and compared with those of nanocomposites processed by conventional mechanical powder mixing and wet powder mixing. The electroless copper plating on the surfaces of the individual CNFs enabled them to become embedded inside copper particles, which successfully solved the non-uniform dispersion of CNFs in Cu matrix, the most important problem in CNF/Cu nanocomposite manufacturing. The CNF/Cu nanocomposite prepared by chemical mixing had well dispersed CNFs, no pores, and no intermediate phase which can be a cause of thermal resistance. Its thermal conductivity was accordingly much higher (435 W/mK) than the nanocomposites processed by mechanical powder mixing and wet powder mixing, as well as the theoretical thermal conductivity of copper (398 W/mK).

Increased thermal stability of nanocellulose composites by functionalization of the sulfate groups on cellulose nanocrystals with azetidinium ions

ABSTRACTCellulose nanocrystals (CNCs) prepared via sulfuric acid hydrolysis are decorated with sulfate groups that yield a stable water suspension. To make the CNCs adaptable for use in composites, the hydroxyl groups on the surface are usually hydrophobized. In this article, an alternative hydrophobization method is described in which the sulfate groups are conjugated with azetidinium salts. The results of this study show that the sulfate groups can be functionalized with azetidinium salts and from thermal studies, it was discovered that the functionalization led to a 100 °C increase in thermal stability, compared with unmodified CNCs. The nanocomposites prepared by extrusion of CNC‐coated low‐density polyethylene powder displayed similar mechanical properties as the CNC‐reference sample, but without the discoloration, due to the increased thermal stability. In conclusion, the azetidinium reagent reacts preferentially with sulfate groups, and this new type of chemical conversion of sulfate groups on polysaccharides will be beneficial in nanocomposite manufacturing. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45963.

The Effect of Ultrasonic Dispersion on the Surface Chemistry of Carbon Nanotubes in the Jeffamine D-230 Polyetheramine Medium

This paper studies changes in the surface chemistry of carbon nanotubes (CNTs) where they are under ultrasonication process in Jeffamine D-230 polyetheramine medium. Jeffamine is used as a curing agent in the nanocomposite manufacturing process. In the nanocomposite technology, ultrasonication process is employed as a method for dispersion of CNTs in a suspension. This research tries to investigate the effect of ultrasonic dispersion with different time and energy on the surface chemistry of CNTs by Fourier transform infrared spectroscopy. The results show ultrasonication of CNTs in the Jeffamine medium leads to significant oxidation and hydration along creating new chemical bonds on the CNTs surface.

Flexible composite via rapid titania coating by microwave-assisted hydrothermal synthesis

The aim of this work was to prepare a flexible nanocomposite from ultra-fine titanium oxide ( $$\hbox {TiO}_{2}$$ ) growth on carbon fibre via microwave-assisted hydrothermal synthesis (MHS) and to evaluate its photocatalytic properties. The $$\hbox {TiO}_{2}$$ nanoparticles were directly grown on the carbon fibre (CF). Thus, a study comparing the conventional titania coating vs. the MHS were performed. The significant layer interaction as a function of the coating method on the visible and dark dye photodegradation performance was observed. Techniques such as X-ray diffraction, electron microscopy (field-emission scanning electron microscope (FESEM)), Raman spectroscopy, among others were used aiming to characterize the different route samples. This study reports a reproducible and single method to manufacture of nanocomposites through the growth of $$\hbox {TiO}_{2}$$ nanoparticle on CF by MHS that allow controlling the thickness layer. Similar procedure of synthesized nanocomposite could be applied in different chemical compositions to advanced applications, based on the electrochemical nanostructure.

Manufacturing of Al-TiB2 Nanocomposites by Flux-Assisted Liquid State Processing

Aluminum matrix nanocomposite (AMNC) materials are of great interests for various structural and functional applications for automotive, aerospace, and military. In this study pure aluminum (Al) with one and two volume percent (vol.%) of titanium diboride (TiB2) nanoparticles were produced via flux-assisted liquid state processing. Adding flux during nanoparticle feeding can significantly improve nanoparticle incorporation into molten Al. TiB2 nanoparticles as small as 100 nm were successfully incorporated into pure Al using potassium aluminum fluoride (KAlF4) flux. TiB2 nanoparticles were fairly distributed and dispersed in the Al-2 vol.% TiB2 nanocomposite. Vickers hardness of the Al-2 vol.% TiB2 nanocomposite was higher than the as-received pure Al. While KAlF4 flux is proven to enhance the nanoparticle incorporation efficiency in Al system, further study is needed to thoroughly remove the flux remnant from Al matrix, to enhance the effect of the TiB2 nanoparticle reinforcement.

Study on Tensile Strength, Impact Strength and Analytical Model for Heat Generation in Friction Vibration Joining of Polymeric Nanocomposite Joints

Polymers reinforced with fillers designated as polymer nanocomposites have become an area of research in the present scenario. The manufacturing of polymeric nanocomposite using Polypropylene (PP) matrix with 2 wt% of Cloisite30B (C30B) in the presence of 15 wt% Elvaloy AC3427 (EA) as compatibilizer by melt intercalation method and injection molding process was used for producing welding samples. X-ray diffraction studies revealed that it has an intercalated polymeric nanocomposite structure which confirms the formation of PP/C30B/EA nanocomposite. In this work, friction vibration joining (FVJ) process was used for joining PP/C30B/EA nanocomposite. In order to study the tensile and impact strength of FVJ joints, a full factorial design was constructed with the factors like (i) tool profiles (cylindrical, square, and triangle); (ii) frequency of the vibrating tool (14, 18, and 22 Hz); and (iii) feed rate of workpiece (6, 12, and 18 mm/min). The analytical model was developed for calculating the heat generation between the tool and PP/C30B/EA nanocomposite plates based on different contact conditions. The field emission scanning electron microscopy (FE SEM) was used to study the relation between the morphology and joint characteristics of PP/C30B/EA nanocomposite. The significance of the factors over tensile and impact strength was also investigated by analysis of variance (ANOVA). POLYM. ENG. SCI., 57:495–504, 2017. © 2016 Society of Plastics Engineers

Dispersion study of clay nanoparticles in vinylester resin

Resistance to sea‐water penetration in fiber‐reinforced polymer composites is highly desirable for marine applications. This can be achieved by incorporating nanoparticles into polymer matrix, due to high aspect ratio of the platelets where small percentage of nanoclay particles properly dispersed in matrix can generate very large surface area for polymer/filler interactions. However, effective dispersion aiming for exfoliation and intercalation of nanoclays in resin is one of the major challenges faced for manufacturing of nanocomposites. In the present work, a suitable protocol is established for effective dispersion of Cloisite 15A nanoparticles in vinylester resin matrix. Dispersion study is conducted for different loading levels of nanoparticles and parameters are optimized. The extent of dispersion is characterized by performing X‐ray diffraction and high resolution transmission electronic microscopic image analysis. It is found that overnight swelling of nanoclays in resin followed by 45 min of ultrasonication at 220 V, 50–60 Hz frequency and 0.5 cycle per sec results in good amount of interaction with certain degree of exfoliation for loading level up to 6%. The nano particle dispersed resin is characterized to study the effect of nanoparticles on key manufacturing properties of resin matrix like rheology and cure kinetics. J. VINYL ADDIT. TECHNOL., 23:E51–E57, 2017. © 2016 Society of Plastics Engineers

The Influence of the Dispersion Method on the Microstructure and Properties of MWCNTs/AA6061 Composites

Abstract The aim of this work was to study the effect of different methods of multi-walled carbon nanotubes (MWCNTs) dispersion, and their influence on the microstructure and properties of aluminium alloy matrix composites produced using the powder metallurgy techniques, such as powder milling/mixing and hot extrusion. The main problem in the manufacturing of nanocomposites is the homogeneous distribution of MWCNTs in the metal matrix. To achieve their proper distribution a high-energy and low-energy mechanical milling, using a planetary ball mill, and mixing, using a turbulent mixer, were applied. Studies have shown that composite materials prepared using milling and extrusion have a much better dispersion of the reinforcing phase, which leads to better mechanical properties of the obtained rods. The low-energy mechanical mixing and mixing using the turbulent mixer neither change the powder morphology nor lead to adequate dispersion of the carbon nanotubes, which directly affects the resulting properties.

Magnetically anisotropic additive for scalable manufacturing of polymer nanocomposite: iron-coated carbon nanotubes

Novel nanoparticles additives for polymer nanocomposites were prepared by coating carbon nanotubes (CNTs) with ferromagnetic iron (Fe) layers, so that their micro-structures can be bulk-controlled by external magnetic field application. Application of magnetic fields is a promising, scalable method to deliver bulk amount of nanocomposites while maintaining organized nanoparticle assembly throughout the uncured polymer matrix. In this work, Fe layers (∼18 nm thick) were deposited on CNTs (∼38 nm diameter and ∼50 μm length) to form thin films with high aspect ratio, resulting in a dominance of shape anisotropy and thus high coercivity of ∼50–100 Oe. The Fe-coated CNTs were suspended in water and applied with a weak magnetic field of ∼75 G, and yet preliminary magnetic assembly was confirmed. Our results demonstrate that the fabricated Fe-coated CNTs are magnetically anisotropic and effectively respond to magnetic fields that are ∼103 times smaller than other existing work (∼105 G). We anticipate this work will pave the way for effective property enhancement and bulk application of CNT–polymer nanocomposites, through controlled micro-structure and scalable manufacturing.

Thermal evolution behavior and fluid dynamics during laser additive manufacturing of Al-based nanocomposites: Underlying role of reinforcement weight fraction

In this study, a three-dimensional transient computational fluid dynamics model was established to investigate the influence of reinforcement weight fraction on thermal evolution behavior and fluid dynamics during selective laser melting (SLM) additive manufacturing of TiC/AlSi10Mg nanocomposites. The powder-to-solid transition and nonlinear variation of thermal physical properties of as-used materials were considered in the numerical model, using the Gaussian distributed volumetric heat source. The simulation results showed that the increase of operating temperature and the resultant formation of larger melt pool were caused by the increase of weight fraction of reinforcement. The Marangoni convection was intensified using a larger reinforcement content, accelerating the coupled motion of fluid and solid particles. The circular flows appeared when the TiC content reached 5.0 wt. % and the larger-sized circular flows were present as the reinforcement content increased to 7.5 wt. %. The experimental study on surface morphologies and microstructures on the polished sections of SLM-processed TiC/AlSi10Mg nanocomposite parts was performed. A considerably dense and smooth surface free of any balling effect and pore formation was obtained when the reinforcement content was optimized at 5.0 wt. %, due to the sufficient liquid formation and moderate Marangoni flow. Novel ring-structured reinforcing particulates were tailored because of the combined action of the attractive effect of centripetal force and repulsive force, which was consistent with the simulation results.

Conductive-on-demand: Tailorable polyimide/carbon nanotube nanocomposite thin film by dual-material aerosol jet printing

A new nanocomposite manufacturing process, Dual-material aerosol jet printing (DMAJP), was developed to fabricate polyimide (PI)/carbon nanotube (CNT) nanocomposite with tailorable and controllable intra-part varying CNT loading. This process mixes the aerosols of CNT ink and a solution of PI precursor to achieve a homogenous dispersion of CNTs in the PI matrix. The mixing ratio of the two aerosols determines the CNT loading in the nanocomposite, which can be used to control the conductivity of the film. Thickness, nanostructure, and conductivity of the nanocomposites fabricated under different process conditions were investigated. The high degree with which the printed PI/CNT nanocomposite film may be tailored was demonstrated through three examples: a film with different CNT loadings at designated regions; a film with a built-in circuit; and a film with a through-thickness conductive channel. DMAJP is a facile, versatile, and potentially scalable manufacturing process for the next generation of smart nanocomposites.

Materials, preparation, and characterization of PVA/MMT nanocomposite hydrogels: A review

This article presents a review of studies on materials, preparation, properties, and characterization of polyvinyl alcohol (PVA) nanocomposite hydrogels. The structure and properties of Montmorillonite, the nanoclay used in the manufacture of PVA nanocomposites and techniques for making PVA nanocomposite hydrogels have been reviewed. The characterization techniques such as Fourier transform infrared spectroscopy (FT‐IR), Differential scanning calorimetry (DSC), Dynamic mechanical analysis (DMA), Scanning electron microscopy, Transmission electron microscopy (TEM), X‐ray diffraction (XRD) are also studied. The XRD patterns and TEM images have proven the intercalated and exfoliated structures of PVA nanocomposite hydrogels that is due to the presence of nanoclay layers. Investigation of FT‐IR spectra shows the bonding formation between OH and silanol groups of PVA and Montmorillonite. Also, the results of DSC and DMA indicated a decrease in crystallinity and the glass transition temperature of PVA by the incorporation of nanoclay, while the loss modulus is increased compared to that of pure PVA. POLYM. COMPOS., 38:1086–1102, 2017. © 2015 Society of Plastics Engineers

Aerosol Emission Monitoring and Assessment of Potential Exposure to Multi-walled Carbon Nanotubes in the Manufacture of Polymer Nanocomposites.

Recent animal studies have shown that carbon nanotubes (CNTs) may pose a significant health risk to those exposed in the workplace. To further understand this potential risk, effort must be taken to measure the occupational exposure to CNTs. Results from an assessment of potential exposure to multi-walled carbon nanotubes (MWCNTs) conducted at an industrial facility where polymer nanocomposites were manufactured by an extrusion process are presented. Exposure to MWCNTs was quantified by the thermal-optical analysis for elemental carbon (EC) of respirable dust collected by personal sampling. All personal respirable samples collected (n = 8) had estimated 8-h time weighted average (TWA) EC concentrations below the limit of detection for the analysis which was about one-half of the recommended exposure limit for CNTs, 1 µg EC/m(3) as an 8-h TWA respirable mass concentration. Potential exposure sources were identified and characterized by direct-reading instruments and area sampling. Area samples analyzed for EC yielded quantifiable mass concentrations inside an enclosure where unbound MWCNTs were handled and near a pelletizer where nanocomposite was cut, while those analyzed by electron microscopy detected the presence of MWCNTs at six locations throughout the facility. Through size selective area sampling it was identified that the airborne MWCNTs present in the workplace were in the form of large agglomerates. This was confirmed by electron microscopy where most of the MWCNT structures observed were in the form of micrometer-sized ropey agglomerates. However, a small fraction of single, free MWCNTs was also observed. It was found that the high number concentrations of nanoparticles, ~200000 particles/cm(3), present in the manufacturing facility were likely attributable to polymer fumes produced in the extrusion process.

Role of Interphase in the Mechanical Behavior of Silica/Epoxy Resin Nanocomposites

A nanoscale representative volume element has been developed to investigate the effect of interphase geometry and property on the mechanical behavior of silica/epoxy resin nanocomposites. The role of interphase–matrix bonding was also examined. Results suggested that interphase modulus and interfacial bonding conditions had significant influence on the effective stiffness of nanocomposites, while its sensitivities with respect to both the thickness and the gradient property of the interphase was minimal. The stiffer interphase demonstrated a higher load-sharing capacity, which also increased the stress distribution uniformity within the resin nanocomposites. Under the condition of imperfect interfacial bonding, the effective stiffness of nanocomposites was much lower, which was in good agreement with the documented experimental observations. This work could shed some light on the design and manufacturing of resin nanocomposites.

The Application of External Fields to the Manufacturing of Novel Dense Composite Master Alloys and Aluminum-Based Nanocomposites

The possibility of producing dense and concentrated master alloys containing nanosized Al2O3 by shock-wave compacting is demonstrated. Different conditions of shock-wave process are discussed. The data of master alloys characterization are presented. The nanostructured master alloys have high density and are convenient for metallurgical handling. It is found that the use of such a master alloy with nanoceramic particles facilitates the particle introduction into the aluminum melt. The ultrasonic treatment performed during and after the introduction of the master alloy into the melt further leads to uniform distribution of strengthening nanoparticles and improvement of alloy strength and ductility. Experimental results are shown and discussed.

Nano-Composite manufacturing using the Electro-Orientation method of Micro/Nano-Particles in a liquid polymer with mechanical characteristics analysis

A new technology for manufacturing micro/nano composites by utilizing an electric field to fabricate particle orientations in a polymer liquid state is developed and its thermo-mechanical properties are tested. This method allows the manipulation of the local orientation of the submerged micro/nano size particles in a liquid matrix. The study demonstrates that the technology is able to locally manipulate the particle orientation and applicable diverse metal/non-metal inclusions in a polymer matrix. The theoretical background of this process includes the dielectrophoresis, diploe moment, and electrophoresis of particles in a polymer matrix. Electrophoresis is an important phenomenon in the orientation of non-spherical particles in a continuous phase. Attempts were made to distribute several types of metal and non-metal particles in a liquid epoxy, in order to test the effects of electrophoresis under an electric field; the rotation and alignment of the particles were clearly observed and pictures were taken. The mathematical models of the kinetic movements caused by the electrophoretic force are also presented here. The results obtained from the experiment indicate the effectiveness of the proposed method and validate the suggested mathematical models, including all of the expanded manipulation.

Microwave Properties of Nanocomposites: Effect of Manufacturing Methods and Nanofiller Structure

Nanocomposite materials filled with multiwall carbon nanotubes (MWCNTs) having three types of structures, i.e., longer (200 μm), shorter (20–50 μm), and aminated (20–50 μm), are manufactured for microwave absorption (MA) in 11–17 GHz frequency range. Microstructure, dielectric permittivity, direct current (DC) electrical conductivity, and MA properties of the MWCNTs–epoxy nanocomposite were investigated. A correlation has been developed between the structure (aspect ratio and surface functionality) of MWCNTs, electrical conductivity of the composite, and MA (return loss (RL)). E-glass/epoxy composite filled with longer carbon nanotubes (CNTs) has shown higher RL as compared to that of other two nanocomposites. The measurements have shown that the magnitude of RL of microwaves depends strongly on the structure of MWCNTs used in the composite. Furthermore, the effect of synthesis route followed for the manufacturing of nanocomposite on its electrical conductivity and microwave absorbing properties is also investigated; three different approaches were followed to manufacture CNT/epoxy nanocomposites from longer CNTs (200 μm).

Manufacture of opal-matrix functional nanocomposites by catalytic dehydrogenation of isopropanol under supercritical conditions

The products of redox reactions that occur during the manufacture of opal-matrix nanocomposites in isopropanol under supercritical conditions are studied. Experimental data, thermodynamic calculations, and reaction yield values imply that hydrogen is formed in the catalytic dehydrogenation of isopropanol to acetone under supercritical conditions. The alcohol dehydrogenation catalysts are ultrafine d-element oxides encapsulated in the pore space of an ordered opal matrix; in a closed experimental system (an autoclave), these oxides are reduced by hydrogen to metals or to lower oxides (or the oxygen stoichiometry of higher oxides changes).

Preparation and characterization of cellulose nanofibers (CNFs) from microcrystalline cellulose (MCC) and CNF/polyamide 6 composites

Microcrystalline cellulose (MCC) and polyamide 6 (PA6) fibers are used for the manufacture of thermoplastic nanocomposites. From the MCC (0.5 wt% of water), the cellulose nanofiber (CNF) with a mean fiber diameter below 30 nm is successfully obtained by a high pressure homogenizer with different processing conditions, such as various number of pass, nozzle size and operation pressure. As the operation pass number and pressure are increased, the specific surface area (SSA) of CNFs is increased due to the fibrillation during the homogenization process. The large surface area of CNF can improve the reinforcement effects for their nanocomposites. The composite papers, consisting of CNFs and PA6 fibers, are fabricated by a wet-laid sheet forming process. In this step, the pre-hydrolyzed silane coupling agent (0.1, 0.5, and 1.0 wt% in water) is added into the CNF slurry. The CNF/PA6 composites are pressed by a high pressure (3.4 and 4.8 MPa) calendering system. The tensile strengths of nanocomposites are increased by more than two times (max. 16.4 MPa) compared to PA6 100% sheets (6 MPa) due to the silane treatment, calendering process and reinforcement of CNFs. Open image in new window