Ultrasonic Dispersion Research Articles

Thermal behavior and combustion performance of Al/Bi2O3 nano thermites with the effect of potassium perchlorate

To study the effect of the addition of potassium perchlorate (KClO4) on the performance of nano thermites, Al/Bi2O3 nano thermites with different mass fraction (wt%) of KClO4 was made by ultrasonic dispersion method. Then, all samples were tested by SEM, DSC and rapid excitation ignition. DSC results showed Al/Bi2O3/10 wt%KClO4 had the highest heat release. Compared with Al/Bi2O3, the heat release increased by 28.32%. The results of activation energy calculations showed Al/Bi2O3/30 wt%KClO4 had the lowest activation energy (Ea). Its activation energy was reduced by 30%, mere about 149.17 KJ mol−1. Finally, it can be seen from the combustion situation that the addition of KClO4 reduced the intensity of burning. This work found a way to increase the heat release or reduce the activation energy of nano thermites by controlling the amount of KClO4 added.

Investigation on effect of nanosilica dispersion on the properties and microstructures of fly ash-based geopolymer composite

Nanosilica-geopolymer composites with different dispersion levels of nanoparticles were investigated on the physical properties and gel properties. The results indicated that compared with the nanosilica-geopolymer composites without ultrasonic dispersion, the 20 and 120 min of sonication brought 3.88% and 13.59% of additional strength enhancement, respectively. For the micromechanical properties of N-A-S-H gel, the better dispersed samples exhibited higher elastic modulus. In comparison to the reference sample, the elastic modulus was increased by 15.18% and 29.93% respectively for samples with 20 and 120 min of sonication. The better dispersed nanoparticles exhibited smaller sizes and increased the physical filling effect which could result in densified microstructures, better bonding behaviors and the both improved micro and macro mechanical properties.

Synthesis, Preparation and Evaluation of Doxorubicin-Loaded Chitosan Oligosaccharide/Indomethacin Nanoparticles

Doxorubicin(DOX)-loaded chitosan oligosaccharide(CSO)/indomethacin(Indo) nanoparticles(NPs) was developed as a uniform particle size, high drug loaded capacity, good biostability and biocompatibility drug delivery system. According to the principle of “Like dissolves like”, Indo was grafted to the bones of CSO under mild condition. The CSO/Indo NPs were formed by ultrasonic dispersion method in the aqueous medium. The critical aggregation concentrations of the CSO/Indo NPs were from 33.89 µg/ml to 287.92 µg/ml. The IC50 of blank CSO/Indo NPs (311.06 µg/ml–1365.3 µg/ml) on HepG2 cell lines indicated that they could be used as safe carriers except CSO18000/Indo100%. DOX–loaded NPs were prepared by a dialysis method. The sizes of drug-loaded NPs were significantly smaller than those of the corresponding blank nanoparticles while all the zeta potentials of drug-loaded nanoparticles were lower than those blank nanoparticles. These data supported our original scientific hypothesis that the π bonds in the structure of CSO/Indo might generate the physical interaction with the π bonds of DOX. Compared with the IC50 of free DOX·HCl solution (8.576 µg/ml), the IC50 of the drug-loaded NPs (3.125 µg/ml—4.524 µg/ml) showed that they had obvious enhanced anti-tumour effect. Therefore, CSO/Indo NPs provided a new choice for insoluble anticancer drugs.

Additive manufacturing of thin electrolyte layers via inkjet printing of highly-stable ceramic inks

Inkjet printing is a promising alternative for the fabrication of thin film components for solid oxide fuel cells (SOFCs) due to its contactless, mask free, and controllable printing process. In order to obtain satisfying electrolyte thin layer structures in anode-supported SOFCs, the preparation of suitable electrolyte ceramic inks is a key. At present, such a kind of 8 mol% Y2O3-stabilized ZrO2 (8YSZ) electrolyte ceramic ink with long-term stability and high solid loading (> 15 wt%) seems rare for precise inkjet printing, and a number of characterization and performance aspects of the inks, such as homogeneity, viscosity, and printability, should be studied. In this study, 8YSZ ceramic inks of varied compositions were developed for inkjet printing of SOFC ceramic electrolyte layers. The dispersing effect of two types of dispersants, i.e., polyacrylic acid ammonium (PAANH4) and polyacrylic acid (PAA), were compared. The results show that ultrasonic dispersion treatment can help effectively disperse the ceramic particles in the inks. PAANH4 has a better dispersion effect for the inks developed in this study. The inks show excellent printable performance in the actual printing process. The stability of the ink can be maintained for a storage period of over 30 days with the help of initial ultrasonic dispersion. Finally, micron-size thin 8YSZ electrolyte films were successfully fabricated through inkjet printing and sintering, based on the as-developed high solid loading 8YSZ inks (20 wt%). The films show fully dense and intact structural morphology and smooth interfacial bonding, offering an improved structural quality of electrolyte for enhanced SOFC performance.

Fabrication of a direct Z-scheme heterojunction between MoS2 and B/Eu-g-C3N4 for an enhanced photocatalytic performance toward tetracycline degradation

A sulfur vacancy (SV)- and nitrogen vacancy (NV)-mediated Z-scheme MoS2/Eu/B-g-C3N4 (MS/BEuCN) photocatalyst was synthesized via thermal polymerization and ultrasonic dispersion methods. Based on the results of various characterizations, a direct Z-scheme heterojunction was successfully constructed between MS and BEuCN, which efficiently promoted photoinduced carrier charge separation and prevented the occurrence of photocorrosion. Meanwhile, the MS/BEuCN composites displayed an enlarged BET specific surface area, widened the visible-light absorption range and accelerated the photoinduced electron-hole pair separation, which significantly promoted photodegradation toward tetracycline (TC). The existence of NVs and SVs had a synergistic effect, providing more active sites, enhancing the visible-light absorbance capacity and promoting the separation of photoinduced carriers charge. The optimized photocatalytic degradation rate of MS/BEuCN could be improved to 99.0%, nearly 1.6, 2.1 and 1.2 times that of MS, CN and BEuCN, respectively. The significant contribution of ·O2− and ·OH in the MS/BEuCN/Vis system was proven via radical quenching experiments and electron spin response measurements (ESR). This work provided a novel combination mode for the construction of high-efficiency heterostructure photocatalysts, which could be applied in environmental restoration.

Low angle-dependent structural colours from redispersion of silica photonic crystal film

Structural colour has attracted more and more attentions owing to its advantages of non-fading, environment friendly and non-toxic. According to its behaviour with respect to the viewing angle, there are two groups: iridescent (angle-dependent) and nor iridescent (angle-independent). However, many applications in textile and fashion require stable colour which means the colour shows low angle dependent. In this work, 314nm silica nanoparticle was synthesized by using a solvent varying technic which based on Stöber method. Iridescent structurally coloured film was directly self-assembled by gravity sedimentation of silica nanoparticle. Then, film was triturated and redispersed by ultrasonic dispersion process. Low angle-dependent structurally coloured film was then obtained by the redispersed silica nanoparticles. The effect of redispersion time on the structural colours was studied. The result shows that a twenty-minute redispersion gives a less bright but low angle-dependent structural colour film.

Solvent-Free Ultrasonic Dispersion of Nanofillers in Epoxy Matrix.

Dispersion of carbon nanotubes and carbon nanofibers is a crucial processing step in the production of polymer-based nanocomposites and poses a great challenge due to the tendency of nanofillers to agglomerate. One of the most effective methods for dispersion is the use of a three-roll mill, which is a well-established method and results in agglomerates below 5 µm. Nevertheless, this process is time-consuming and thus a limiting factor for industrial applications. Our aim was to establish an easy and efficient ultrasonic dispersion process, characterize the dispersion parameters, and compare both methods, ultrasonication and the three-roll mill. We applied rheological tests and analyzed the agglomerate sizes by an image fit of the microscopy images. All these analyses combined deliver a valuable set of information about the dispersion’s quality and, therefore, allows the improvement and further adaptation of the dispersion process.

ОСОБЛИВОСТІ ВПЛИВУ НАНОМАТЕРІАЛІВ НА ЕКРАНУВАННЯ ЕЛЕКТРОМАГНІТНОГО ВИПРОМІНЮВАННЯ КОМПОЗИТАМИ

The use of nanomaterials as a composite material to improve the efficiency of a protective coating for shielding against electromagnetic interference. Samples were studied using equipment from Keycom Corp. (Japan) developed for measuring the shielding effect. Ultrasonic dispersion of nanomaterials was performed using a UZDN-A1200T ultrasonic disperser. The resistivity of the composite coatings was measured using a ST2558B-F01 standardized 4-electrode cell. The influence of various nanomaterials on the protective properties of thin carbon-polymer coatings has been established. The following nanomaterials have been investigated: boron oxide and carbide, iron oxide, carbon nanotubes, and graphene. The dependence of the resistivity of the coating and the shielding effect on the type of nanomaterial in the composite sample has been established. It has been experimentally proved that the ultrasonic dispersion can improve the shielding effect by 2.5 times. It has been found that graphene has a slight advantage compared to other carbon materials. Also, our results have been established that non-conductive materials such as nano-oxides of iron, boron, and boron carbide can be quite effective for creating radio-absorbing composite materials. The paper proposes a new approach to obtain thin protective coatings against electromagnetic radiation using nanomaterials such as boron carbide, boron oxide, iron oxide, some types of carbon nanotubes, and graphene. The paper proposes a unique algorithm for the ultrasonic dispersion of nanomaterials for the manufacture of composite materials. For the first time, an analysis of the shielding effect of coatings based on domestic materials using international standardized research methods has been carried out. Composite coatings can primarily be used to protect humans from electromagnetic radiation. The materials can be widely used to solve the problems of shielding premises, equipment, in the military, and medical industries.

Effect of Al-3 wt% Al2O3 master alloy fabricated by calcined kaolin on grain refinement and mechanical properties of A356 alloy

In the present study, Al-3 wt% Al2O3 master alloy was successfully prepared by the reaction between calcined kaolin and aluminum melt, combined with mechanical stirring and high-energy ultrasonic dispersion technology. The γ-Al2O3 particles produced by the reaction are uniformly dispersed in the matrix, and the average size of γ-Al2O3 is about 65 nm. The refinement effect of Al-3 wt% Al2O3 master alloy on A356 alloy was studied. It was found that the α-Al grain size in A356 alloy refined by Al-3 wt% Al2O3 master alloy was decreased from 980 ± 155 µm to 337 ± 95 µm. Compared with the Al-5Ti-1B master alloy, Al-3 wt% Al2O3 has a higher refinement efficiency. In addition, the refinement efficiency of the Al-3 wt% Al2O3 master alloy will not fade within 60 min. Transmission electron microscope analysis showed that the orientation relationship between γ-Al2O3 and Al was (22−2)γ-Al2O3[011]γ-Al2O3//(11−1)Al[011]Al, which demonstrated that γ-Al2O3 could be used as heterogeneous nucleation sites to refine α-Al grains. Moreover, the tensile properties of A356 alloy had been significantly improved.

Influence of Piezoelectric Properties on the Ultrasonic Dispersion of TiO2 Nanoparticles in Aqueous Suspension.

In this study, the soft-type and hard-type lead zirconate titanate (PZT) ceramics were compared in order to create an optimal system for ultrasonic dispersion of nanoparticles, and sound pressure energy for each PZT ceramic was analyzed and closely examined with ultrasonic energy. TiO2 was water-dispersed using the soft-type and hard-type PZT transducer, possessing different characteristics, and its suspension particle size and distribution, polydispersity index (PDI), zeta potential, and dispersion were evaluated for 180 days. Furthermore, it was confirmed that the particles dispersed using the hard-type PZT transducer were smaller than the particles dispersed using the soft-type PZT by 15 nm or more. Because the hard-type PZT transducer had a lower PDI, uniform particle size distribution was also confirmed. In addition, by measuring the zeta potential over time, it was found that the hard-type PZT transducer has higher dispersion safety. In addition, it was confirmed that the ultrasonically dispersed TiO2 suspension using a hard-type PZT transducer maintained constant particle size distribution for 180 days, whereas the suspension from the soft-type PZT aggregated 30 days later. Therefore, the hard-type PZT is more suitable for ultrasonic dispersion of nanoparticles.

Effect of sintering insulation time on the properties and microstructure of graphite-copper composite

The copper powder and graphite powder were used as raw materials to fabricate the graphite-copper composite by low temperature cold pressure powder metallurgy sintering method. The powders were mixed by ultrasonic dispersion and mechanical ball grinding process. The effects of sintering insulation time on the properties and microstructure of graphite-copper composite were investigated. The result showed that the distribution of graphite on the copper matrix was uniformly and formed a good interface by using the ultrasonic dispersion and mechanical ball grinding process. When the sintering insulation time was raised from 3 hours to18 hours, the friction coefficient and wear rate were decreased in the initial stage (from 3 hours to 12 hours) meanwhile the Vickers hardness (HV0.5) reached its maximum value 61.9HV when the sintering insulation time was 12 hours. The SEM (scanning electron microscope) images indicated that the increased sintering insulation time was helpful to distribute the graphite phased in composite relatively homogeneous with the sintering insulation time within 12 hours. However, the properties of graphite-copper composite also showed a downward or stable trend with the sintering Insulation time increasing from 12 hours to 18 hours.

Effect of mechanical ball grinding time on the properties and microstructure of graphite-copper composite

In this paper, the graphite-copper composite was prepared by powder metallurgy sintering method which used copper powder and graphene powder as raw materials. The powders were mixed by ultrasonic dispersion and mechanical ball grinding method. The effect of mechanical ball grinding time on the properties and microstructure of graphite-copper composite was investigated using Optical microscope, scanning electron microscope (SEM) and Vickers hardness meter. The result showed that the distribution of graphite in the copper matrix was uniformly and formed a good interface by using the ultrasonic dispersion and mechanical ball grinding method. When the mechanical ball grinding time was raised from 2 hours to 16 hours, the relative density and Vickers hardness of the graphite-copper composite reached their maximum value, the relative density was 92.1%, the Vickers hardness (HV0.5) was 61.9HV. However, the properties of graphite-copper composite showed a downward or stabilize trend the mechanical ball grinding time increasing from 16 hours to 48 hours.

ПОЛУЧЕНИЕ ГРАФЕНОВЫХ СТРУКТУР И НАНОПОЛИМЕРОВ С ИСПОЛЬЗОВАНИЕМ УЛЬТРАЗВУКОВЫХ КОЛЕБАНИЙ

Graphene-based polymer nanocomposites are considered a promising class of future materials. The degree of filling, the filler and binder nature, and the shape, size, and mutual arrangement of filler particles determine the properties of a polymer composite material. The destruction of nanoparticles aggregates occurs most effectively in liquid media under the action of ultrasonic vibrations. The authors proposed the technique and designed laboratory equipment for ultrasonic treatment of the finely-dispersed graphite suspension, carried out the ultrasonic treatment (UST) of finely-dispersed graphite powder. The suspensions based on graphite with a solvent were obtained. The authors carried out the experiments on producing graphene using the graphite liquid-phase exfoliation method at the ultrasonic treatment with different ultrasonic treatment times, analyzed experimental data, and selected the UST optimal time. The paper contains the results of the study of the effect of the graphite suspension base on the degree of ultrasonic liquid-phase exfoliation of graphite. The most effective synthesis of graphene structures using UST is synthesis from graphite suspensions based on dichloroethane, benzol, and dichlorobenzene. Graphene structures’ output ratio amounts to up to 66 %. The authors developed the technology for producing polymers modified with graphene structures using ultrasonic dispersion. Based on graphene synthesized by the graphite liquid-phase exfoliation, the authors obtained nanopolymers using ultrasonic vibrations, carried out DSC measurements, and studied their strength properties. The limit strength of elastic polymers is from 1.9 to 3.6 MPa at different concentrations of graphene inclusions. The residual elongation of samples within the deviation did not change and amounted to 200 %.

Influence of CNT, graphene nanoplate and CNT-graphene nanoplate hybrid on the properties of lightweight concrete

Abstract This study is aimed to investigate the influence of carbon nanotubes and graphene nanoplates on the properties of lightweight concrete. Several lightweight concrete specimens were prepared with different concentrations of carbon nanotube, graphene nanoplates, and combinations of graphene nanoplates and carbon nanotubes. The concrete specimens were prepared both with and without the ultrasonication dispersion method to differentiate between the properties of lightweight concrete. The results indicate that the compressive strength of lightweight concrete samples was slightly increased by the incorporation of carbon nanotubes and graphene nanoplates. The utilization of the ultrasonication energy method was found to be more effective to improve the mechanical performance of lightweight concrete than the composite specimen prepared without the ultrasonication energy method. The composite specimens prepared with carbon nanotubes shows higher improvement in compressive strength than the concrete specimen prepared with the same concentration of graphene nanoplates. While the maximum improvement in compressive strength was noticed for the composite samples prepared with the combination of carbon nanotubes and graphene nanoplates.

Electron-paramagnetic resonance and infrared spectroscopic research of the structure of a southfield Polyvinylidene difluoride near the percolation threshold

In this paper, the results of scientific research work are carried out to study the role of the interfacial layer in filled polymer materials using infrared and electron-paramagnetic resonance spectroscopy using the fundamentals of solid-state physics. At the same time, the authors of this work used all the rich experience of both experimenters and theoreticians working in this field of science and their own developments regarding methods for controlling the structure of these materials. It is noteworthy that the material interpreted in this work concerns composites subjected to special technological preparation, including the stage of ultrasonic dispersion of filler particles in a binder medium.

Performance of the highly sensitive humidity sensor constructed with nanofibrillated cellulose/graphene oxide/polydimethylsiloxane aerogel via freeze drying.

A kind of capacitive humidity sensor with high sensitivity constructed with nanofibrillated cellulose (NFC), graphene oxide (GO) and polydimethylsiloxane (PDMS) is presented in this work, via a simple ultrasonic dispersion and freeze drying technology. The NFC and GO with a strong adsorption for water molecules were used as a substrate for the promotion of capacitive response of the humidity sensor. Moreover, anhydrous ethanol was added to inhibit the generation of big cracks in the humidity sensor in the freeze drying process, so as to obtain a regular network porous structure, then providing a great deal of conduction channels and active sites for molecular water. Also, the addition of PDMS can effectively enhance the flexibility and stability of its porous structure. The results confirmed that the humidity sensor with 30 wt% GO showed an excellent humidity sensitivity (6576.41 pF/% RH), remarkable reproducibility, low humidity hysteresis characteristic in 11–97% relative humidity (RH) at 25 °C, and short response/recovery times (57 s/2 s). In addition, the presented sensor exhibited small relative deviation of the measured relative humidity value compared with the commercial hygrometer. The realization of the high sensitivity can be attributed to the theories about interaction of the hydrophilic group, proton transfer of water molecules and the three-dimensional network transport structure model. Therefore, the NFC/GO/PDMS humidity sensor finally realizes stable, reproducible and fast humidity sensing via an eco-friendly process, exhibiting promising potential for wide practical application.

PEG-interpenetrated genipin-crosslinked dual-sensitive hydrogel/nanostructured lipid carrier compound formulation for topical drug administration

PEG-interpenetrated dual-sensitive hydrogels that load nano lipid carrier (NLC) were researched and developed for topical drug administration. Natural antioxidant α-lipoic acid (ALA) was selected as our model drug. The α-lipoic acid (ALA) nano lipid carrier was successfully prepared by hot melt emulsification and ultrasonic dispersion method, and the physicochemical properties of the nano lipid carrier were investigated, including morphology, particle distribution, polydispersity coefficient, zeta potential and encapsulation efficiency. Carboxymethyl chitosan and poloxamer 407 contributed to pH- and temperature-sensitive properties in the hydrogel, respectively. Natural non-toxic cross-linking agent genipin reacted with carboxymethyl chitosan to form the hydrogel. Poly ethylene glycol (PEG), a polymer compound with good water solubility and biocompatibility, interpenetrated the hydrogel and influenced the mechanical strength and drug release behaviour. FI-IR test verified the successful synthesis of the hydrogel. The rheological parameters indicated that the mechanical strength of the hydrogel was positively correlated with the amount of PEG, and the in vitro dissolution profiles demonstrated that the increasement of PEG could accelerate the drug release rate. The compatibility of the drug delivery system was verified with cells and mice model. Topical delivery of ALA in solution, NLC and NLC-gel was investigated in-vitro.

Preparation, Characterization and Antiproliferation Evaluation of Nanoliposome Loaded with Anthocyanins

This study aimed to investigate the nanoliposomes composed of soy lecithin and cholesterol for encapsulation of anthocyanins (ACNs) by thin film ultrasonic dispersion method. The processing conditions of ACNs nanoliposomes (ANLs) were optimized, and the ANLs were characterized by average particle size, zeta (ζ)-potential and polydispersity index (PDI). Their storage stability under various pH, temperature, light conditions, and in vitro antiproliferative effect were analyzed. The optimal preparation parameters were suggested to be soy lecithin to cholesterol ratio of 80 mg to 19 mg (w/w, 2 mg of ACNs) by using ultrasonication at 120 W for 3.12 min. The produced ANLs had the encapsulation efficiency of 40.1 % with average particle size of 117 nm, PDI of 0.254 and ζ-potential of 8.56 mV. These ANLs presenting ≈ 130 nm of stable sizes at tested pH conditions. The ACNs showed better in vitro antiproliferative effect for two cancer cell lines than ANLs, while ANLs were more stable against temperature and light. The ACNs in nanoliposomes displayed higher retention efficiency than that of in solution under various storage conditions. This study provides a promising approach for stabilizing ACNs-containing food ingredients, which displays large potentiality in the productions of nutraceutical and functional foods.

A self-supported electrode for supercapacitors based on nanocellulose/multi-walled carbon nanotubes/polypyrrole composite

A robust self-supported electrode based on nanocellulose fibers (CNF), multi-walled carbon nanotubes (CNT), and polypyrrole (PPy) was prepared by a facile combination of ultrasonic dispersion and consequent in situ polymerization. In addition, the feasibility of utilizing this ternary composite as an electrode for supercapacitors was studied. The results revealed that the obtained CNF/CNT/PPy composite exhibited a large specific capacitance of 200.8 F g−1 at 0.5 A g−1. Equally important, the electrode capacitance retained about 90% of its initial value after 5000 charge/discharge cycles at a current density of 1 A g−1, which thus demonstrated its excellent cycling stability. The simple integration route and outstanding electrochemical properties distinguish this new composite as a prospective candidate for use as a high-performance electrode in supercapacitors.

Модифицирование межфазного слоя армированных полимерных композитов нанодисперсным диоксидом кремния

The behavior of colloidal silicon dioxide in a composition with a styrene / butyl acrylate oligomer, grafted onto a thermoplastic polyamide adhesive to obtain a branched binder structure with penetration of branches into the capillary-pore system of the reinforcing fiber component, was studied. The variants of disaggregation of SiO2 using ultrasonic treatment and mechanical activation with exposure by high shear stresses, ultrasound and cavitation are compared. Methods of dynamic light scattering, IR spectroscopy, thermal analysis, and textile materials science were used to evaluate the elastic-deformation properties of duplicated packets. The set of complementary results confirms that the combined mechanical activation of an aqueous dispersion of oligoacrylate and silica causes the destruction of silica nanospheres and the formation of a hybrid oligolymer-inorganic adduct. In contrast to the short-term effects of ultrasonic dispersion of SiO2, joint mechanical activation of the components solves the problems of preventing aggregation of nanoparticles and uniform distribution of the reinforcing filler in the composite. The effectiveness of using the method for regulating the properties of forming units and parts of sewing products is shown. When selecting oligoacrylate, specific for sewing production separation of the stages of preliminary bonding of materials using thermoplastic adhesive, the creation of a finished product form and its fixing during wet-heat treatment, is taken into account. The preparation of a hybrid adduct of mechanical activation provides an optimal ratio of particle size for rational distribution of fractions in interfacial, interfiber, and intrafiber spaces of the textile web. The shift of the peaks of phase transitions and chemical transformations in a system with nanodispersed SiO2, controlled on DSC thermograms, is consistent with the temperature regimes of successive stages of the technological process. The possibilities of a controlled change in the properties of forming composite materials and a decrease in the material consumption of sewing products by grafting a modified oligoacrylate with a variable content of silicon dioxide are demonstrated.