Dispersed Composites Research Articles

Formation of Superhydrophobic Coatings Based on Dispersion Compositions of Hexyl Methacrylate Copolymers with Glycidyl Methacrylate and Silica Nanoparticles

In the last decade, the task of developing environmentally friendly and cost-effective methods for obtaining stable superhydrophobic coatings has become topical. In this study, we examined the effect of the concentrations of filler and polymer binder on the hydrophobic properties and surface roughness of composite coatings made from organic–aqueous compositions based on hexyl methacrylate (HMA) and glycidyl methacrylate (GMA) copolymers. Silicon dioxide nanoparticles were used as a filler. A single-stage “all-in-one” aerosol application method was used to form the coatings without additional intermediate steps for attaching the adhesive layer or texturing the substrate surface, as well as pre-modification of the surface of filler nanoparticles. As the ratio of the mass fraction of polymer binder (Wn) to filler (Wp) increases, the coatings show the lowest roll-off angles among the whole range of samples studied. Coatings with an optimal mass fraction ratio (Wn/Wp = 1.2 ÷ 1.6) of the filler to polymer binder maintained superhydrophobic properties for 24 h in contact with a drop of water in a chamber saturated with water vapor and exhibited roll-off angles of 6.1° ± 1°.

A comparison of visual and molecular methods for inferring biological communities in aquaculture enriched sediments - Impact assessment and cost-benefit analysis

Nutrients introduced to the environment by finfish aquaculture pose environmental risks, which can be mitigated by robust environmental monitoring. Biological communities in soft sediments are good indicators of aquaculture derived environmental changes. Traditionally, monitoring programs have visually surveyed macrofauna communities. However, DNA metabarcoding is a potentially more efficient alternative. We compared alpha diversity, multivariate dispersion and taxonomic composition of macrofauna communities with metabarcoding derived bacterial and eukaryote communities along an organic enrichment gradient at a salmon farm in Tasmania, Australia. Additionally, we conducted a cost-benefit analysis comparing the approaches. All methods identified indicator taxa that changed in abundance over the enrichment gradient. Macrofauna analysis was the most sensitive method for detecting changes in alpha diversity, while metabarcoding was most sensitive for multivariate dispersion. Taxonomic composition of animal communities derived from the two methods differed drastically. Metabarcoding was cheaper than macrofauna for ≥93 samples and quicker for ≥14 samples.

Enhancing thermo-physical properties of hybrid nanoparticle-infused medium temperature organic phase change materials using graphene nanoplatelets and multiwall carbon nanotubes

Phase change materials (PCMs) have emerged as an intriguing option for the storage of thermal energy because of their remarkable capacity to store latent heat. However, the practical application of these materials is hindered by their low thermal conductivity and limited photo-absorbance. For this investigation, graphene nanoplatelets (GNP) and multiwall carbon nanotubes (MWCNT) hybrid nanoparticles were disseminated in RT-54HC organic PCMs at different weight fractions. The nanoparticles were incorporated into the base PCMs using a melt blending technique. Based on the findings, one combination of GNP to MWCNT in a 0.25:0.75 ratio has shown the highest thermal conductivity, with an increase of 40% (0.28 Wm−1 K−1) compared to other hybrid combinations. This breakthrough could potentially open new avenues in the field of thermal energy storage. The chemical stability of the hybrid nanoparticle dispersed composites was assessed through FTIR analysis. In addition, the composites exhibited excellent thermal stability, maintaining their structural integrity even at temperatures as high as 300 ℃. The melting temperature of the composites also showed minimal variation. Based on the evaluation of latent heat enthalpy, the organic PCM known as base RT-54HC demonstrated a heat storage capacity of 230 J/g. However, the composites exhibited a slight decrease in latent heat with increasing nanoparticle weight fraction. In addition, the composite with added hybrid nanoparticles demonstrated an increase in optical absorbance, accompanied by a decrease in transmissibility. Therefore, the hybrid nano-enhanced composites have demonstrated enhanced thermo-physical properties, making them not only suitable but also highly promising for use in applications with mid-range melting temperatures.Graphical

Mechanical, dry sliding wear and tensile fatigue behaviour of rice hush ash–derived silicon carbide dispersed LM25 metal matrix composites

Mechanical, dry sliding wear and tensile fatigue behaviour of rice hush ash–derived silicon carbide dispersed LM25 metal matrix composites

Virtual laboratories for study technologies of environmental protection

Abstract This work is devoted to the use of virtual work for teaching bachelors in technologies of environmental protection. An analysis of publications in the field of using virtual laboratories in universities was carried out. The use of virtual laboratory work supports modern approaches to education, stimulates the learning process and creates conditions for more effective mastery of the material. The article describes an example of the development of laboratory work to determine the parameters of the dispersed composition of dust. Virtual laboratory work is developed as a web application, has a user-friendly interface, all data is saved into a database. Students can work at their own pace, repeat experiments, and adapt their approach to learning. The presented virtual laboratory is relevant to use in distance learning.

Dust Pollution in Construction Sites in Point-Pattern Housing Development

Construction in cities and agglomerations is one of the main sources of air pollution in most countries in the world. Fine dust particles, PM0.5–PM10, which form as a result of construction processes, are among the most dangerous pollutants. With the increase in the volume of point-pattern housing development in cities, the task of maintaining clean air and environmental conditions becomes important. This requires research, the monitoring of dust emissions throughout the entire construction period and the development of design solutions based on the results obtained. The study examines the determination of the dispersed composition of dust generated on a construction site. A graphical representation of the dispersed composition is given by constructing integral curves on a logarithmic grid and approximating them using two-link and three-link splines. The gravimetric measurement method was used to analyze the concentration of dust in the air released during construction work near residential areas. Dust analysis at the construction site revealed significant differences in particle size that cannot be explained by statistical errors alone. The reasons for this are both working conditions and climatic factors, including humidity and wind intensity. In this regard, it is preferable to use models that take into account random processes instead of traditional deterministic methods to study the dust that shapes during construction.

Role of the novel aloe vera-based titanium dioxide bleaching gel on the strength and mineral content of the human tooth enamel with respect to age.

There has been an increased demand for dental bleaching globally irrespective of age and gender. Main drawbacks associated with conventional tooth bleaching agents have been compromised strength and mineral-content of tooth enamel which results in sensitivity, discomfort, roughness, and structure loss of human teeth. Currently, nanoparticles synthesized by green synthesis have gained popularity especially in medical and dental applications because of their versatile and beneficial nano-scaled features. Titanium dioxide nanoparticles (TiO2Nps) in this study were prepared from green ecofriendly source using the aloe vera plant extract and were then characterized via dynamic light scattering (DLS), scanning electron microscope (SEM), X-ray diffraction spectroscopy (XRD), and energy dispersive X-ray (EDX), for size, shape, composition and true-phase. These TiO2 Nps were incorporated in commercial bleaching gel containing hydrogen peroxide to form a novel TiO2-bleaching gel which was used to bleach extracted anterior teeth belonging to four different age groups: 20-29 years, 30-39 years, 40-49 years and ≥50 years. These teeth were investigated for micro-hardness (Vickers microhardness tester) and mineral-content (EDX spectroscopy) including sodium, magnesium, phosphorus, calcium in an in-vitro environment both before and after bleaching. Results revealed that TiO2 Nps prepared by aloe vera plant were nanos-sized of about 37.91-49 nm, spherical shape, true anatase phase with pure titanium and oxygen in their composition. The values of Vickers micro-hardness and mineral-content (Na, Mg, P, Ca) of enamel specimens belonging to different age groups enhanced in a linear pattern before bleaching with the increase in age (p value < 0.05). There was negligible reduction observed in Vickers micro-hardness and mineral-content elements (Na, Mg, P, Ca) of all enamel specimens belonging to different ages after the bleaching (p value > 0.05). The novel TiO2-bleaching gel prepared was effective enough in preventing the declination in Vickers micro-hardness strength and mineral-content of all the enamel specimens belonging to different age groups even after the bleaching procedure which makes it a promising biomaterial.

Investigations on the dielectric properties of solution-casted B4C and PbO dispersed epoxy composites

Investigations on the dielectric properties of solution-casted B4C and PbO dispersed epoxy composites

One-pot synthesis of supported PtCox bifunctional catalysts for oxygen reduction and hydrogen evolution reactions

Hydrogen fuel cells and water electrolyzers hold significant potential for net zero emission and climate change mitigation, but their practical applications are limited by the use of the precious-metal platinum as catalysts. In this study, a one-pot method is developed for the synthesis of PtCox alloys supported on hybrid carbon materials, and it is found that the developed catalysts with reduced Pt loading can act as excellent bifunctional catalysts for both oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER). Morphology and composition characterizations indicate uniform dispersion and adjustable composition of PtCox alloys with the particle size of ∼3 nm on the carbon support. Among them, Pt3Co/C achieves the highest ORR performance with a high mass activity of 179.23 A/g and a specific activity of 3.15 A/m2 in acidic condition, and an extremely low overpotential of 47.6 mV at 10 mA/cm2 in alkaline media as a HER catalyst. This study presents a cost-effective approach for the development of high performance PtCox/C catalysts, and confirms their potential application in hydrogen energy technologies.

Study of dielectric properties of polymer/air plasma treated graphene oxide nanocomposites for electronic applications

In the present study we emphasized on the dielectric properties of Ethylene Vinyl Acetate (EVA) filled with untreated and plasma-treated graphene oxide (GO). The chemical fingerprints of EVA/GO were analysed using FTIR. Decreased ID/IG ratio from 2.99 to 2.75 and 1.60 to 1.16 due to exposed plasma was confirmed by Raman spectroscopy. X-ray diffraction (XRD) disclosed the decreased degree of crystallinity. Electric properties were measured by impedance analyser, dielectric constant was increased upto 11% for untreated GO dispersion and 47% for Air treated Plasma GO dispersed EVA composites. Plasma treatment further improved the exfoliated sites of GO and induced the defects, leading to optimized dielectric properties. Improved dielectric properties of EVA/GO can provide valuable insights into the potential applications in the field of electrical connectors, film capacitors, and pseudo capacitors.

Do all ceramic and composite CAD-CAM materials exhibit equal bonding properties to implant Ti-base materials? An Interfacial Fracture Toughness Study

ObjectivesTo compare the interfacial fracture toughness (IFT) with or without aging, of four different classes of CAD-CAM ceramic and composite materials bonded with self-adhesive resin cement to titanium alloy characteristic of implant abutments. MethodsHigh translucent zirconia (Katana; KAT), lithium disilicate-based glass-ceramic (IPS. emax.CAD; EMX), polymer-infiltrated ceramic network material (PICN) (Vita Enamic; ENA), and dispersed filler composite (Cerasmart 270; CER) were cut into equilateral triangular prisms and bonded to titanium prisms with identical dimensions using Panavia SA Cement Universal. The surfaces were pretreated following the manufacturers’ recommendations and developed interfacial area ratio (Sdr) of the pretreated surfaces was measured. IFT was determined using the Notchless Triangular Prism test in a water bath at 36 °C before and after thermocycling (10,000 cycles) (n = 40 samples/material). ResultsIFT of the materials ranged from 0.80 ± 0.25 to 1.10 ± 0.21 MPa.m1/2 before thermocycling and from 0.71 ± 0.24 to 1.02 ± 0.25 MPa.m1/2 after thermocycling. There was a statistical difference between IFT of CER and the two top performers in each scenario: KAT and EMX before aging, and KAT and ENA after aging. Thermocycling significantly decreased IFT of EMX. The Weibull modulus of IFT was similar for all materials and remained so after thermocycling. Sdr measurements revealed that ENA (7.60)>Ti (4.97)>CER (2.85)>KAT (1.09)=EMX (0.96). SignificanceDispersed filler CAD-CAM composite showed lower performance than the other materials. Aging only affected IFT of Li-Si glass-ceramic, whereas zirconia and PICN performed equally well, probably due to their chemical bonding potential and surface roughness respectively.

The process of sucrose crystallization in the supersaturated solution

Crystallization processes of the solid phase in supersaturated solutions of products of plant origin are used in processing technologies. The theory of diffusion (molecular) mass transfer of the target substance has become widespread when solving problems of technology improvement. The driving force of this process is the difference in the concentration of the solid phase in the solution towards the crystallization center, where the concentration of the solid phase is reduced. During the analytical and quantitative study of the process of solid phase deposition in the crystallization center, Fick's diffusion laws have been used. The influence of solution temperature, concentration of the solid phase, its geometry and dispersed composition on the course of this process have been considered. Based on a diffusion model of the process of crystal formation of sucrose in a vacuum apparatus, a numerical analysis of factors in sugar production technology not covered in the literature has been presented. The problem of quantitative analysis of the process of sucrose crystallization in the working volume of a vacuum apparatus for the production of sugar and other products of plant origin of high commercial standards requires further in-depth study.

Study and mechanism of formation of phosphorus production waste in Kazakhstan

Abstract This article contains information about the accumulated industrial waste from phosphorus production and methods for its recycling and disposal to produce marketable products. Monitoring of cottrel dust’s impact on the environment, namely, ground and surface water, soil, and atmosphere was carried out. The mechanism of formation of cottrel dust was studied. The dispersed, chemical, and phase compositions of the dust in furnace gases during the electrothermal smelting of phosphorites were determined. The sequence of chemical reactions during the formation of cottrel dust was elucidated. The ratios of initial components entering the chemical reaction and the thermodynamic parameters (Gibbs energy) were determined using the Chemistry HSC-6 software package. IR spectral and elemental analyses were carried out for determining cottrel dust’s functional groups and elemental composition. Based on modern instrumental studies, it was found that the total content of phosphorus(v) oxide in cottrel dust was 30.7%. This content of phosphorus(v) oxide is sufficient to use cottrel dust as an initial raw material for producing phosphorus-containing fertilizers. This method was proposed for processing cottrel dust to produce monocalcium phosphate on a production scale. The chemical composition of the resulting monocalcium phosphate was determined and confirmed by analytical methods. The proposed technology for producing monocalcium phosphate from cottrel dust is recommended for use in the agro-industrial complex.

Integrative approach for improved dofetilide solubility using β-cyclodextrin and two its substituted derivatives: Solutions and solid dispersions

The complexation an anti-arrhythmia drug dofetilide (DFT) with β-cyclodextrin (β-CD), 2-hydroxypropyl-β-cyclodextrin (HP-β-CD) and sulfobutylether-β-cyclodextrin (SBE-β-CD) were studied using two main approaches: phase solubility diagrams and solid dispersions technique. The phase solubility diagrams were constructed in buffer solutions with physiological values рН 2.0 и 7.4. In accordance with the protolytic properties of the drug, the solubilizing effect of cyclodextrins turned out to be more effective in a neutral environment (buffer pH 7.4): the solubility improvement of DFT in the presence of β-CD, HP-β-CD and SBE-β-CD was 3.6, 11.8 and 18.1 times, respectively. In buffer pH 2.0, the tendency for an increase in the solubilizing effect, depending on the chemical nature of the CDs used, is maintained, but the solubility of the drug almost does not grow. The binding constants for the DFT/HP-β-CD and DFT/SBE-β-CD complexes equal to 344 L·mol−1 and 429 L·mol−1 in buffer pH 7.4 indicate the formation of stable inclusion complexes and belong to the optimal range for refinement bioavailability and stability of hydrophobic drugs. Amorphous solid dispersions DFT/β-CD, DFT/HP-β-CD and DFT/SBE-β-CD with stoichiometry 1:1 were obtained by grinding method. The combination FTIR, PXRD, DSC, TGA and SEM methods confirmed the inclusion complexes formation of the drug with cyclodextrins used. Dissolution profiles of solid dispersions DFT/β-CD, DFT/HP-β-CD and DFT/SBE-β-CD were graphing in buffer solutions рН 2.0 and 7.4. Enlargement factor of DFT solubility in the composition of solid dispersions DFT/β-CD, DFT/HP-β-CD and DFT/SBE-β-CD in the neutral medium are 3.4, 4.1 and 5.2, respectively. Whereas the formation of solid inclusion complexes DFT/CDs in an acidic buffer has virtually no effect on the increase in the equilibrium concentration of the active substance in the solution. Findings have demonstrated that the use of SBE-β-CD shows the best solubilization potential for DFT both in solution and as a solid dispersion.

Effect of dual dispersion of carbon fiber and silica nanoparticles on recovery performance of shape memory epoxy

Shape memory polymers are utilized in diverse fields, including deployable structures and components, owing to their advantageous properties like low density, cost-effectiveness, and ease of processing. The current study investigates the effect of dual dispersion of carbon fibers (CF) and silica nanoparticles (SN) on the recovery performance of shape memory epoxy composites. CF (0.25 wt.%) reinforced epoxy composite, SN (0.25 wt.%) reinforced epoxy composite, and dual (CF and SN 0.25 wt.% each) dispersed epoxy composite were developed using magnetic stirring and ultrasonic mixing to study the mechanical properties and shape memory behaviour. Flexural strength, tensile strength and fracture toughness of pristine epoxy was found to be 134.38, 52.15 MPa and 1.91 MPa∙m1/2, respectively. The addition of CF resulted in a flexural strength of 135.70 MPa and a tensile strength of 53.01 MPa, while the incorporation of SN led to a flexural and tensile strength of 138.40 and 53.69 MPa, respectively. The fracture toughness of composites after adding CF and SN was found to be 2.22 and 2.39 MPa∙m1/2, respectively. With dual dispersion, the flexural strength of 139.82 MPa, tensile strength of 54.64 MPa, and fracture toughness of 2.75 MPa∙m1/2 were achieved. Dual dispersion has shown improved mechanical properties compared to single dispersion. The introduction of CF slightly decreased the shape fixity ratio (Rf ) and shape recovery ratio (Rr ) of the pristine epoxy from 98.67% and 96.62% to 96.67% and 95.15%, respectively. Similarly, the addition of SN further reduced these ratios to 98.00% and 91.83%, respectively. With a dual dispersion approach Rf and Rr were observed to be about 97.33% and 93.83%, respectively. The addition of fillers led to a reduction in Rf and Rr due to inhibition of polymeric chains, resulting in partial shape recovery. However, recovery time improved from 28 to 23 and 26 s with addition of CF and SN, respectively, in epoxy. With dual dispersion, a speedy recovery was achieved with a recovery time of 21 s. The findings of this study demonstrate the potential of dual dispersed fillers to improve the mechanical and shape memory properties of epoxy, which could find applications in the smart materials and structural engineering.

Preparation and tribological properties of porous polyimide modified by graphene

PurposeThe purpose of this article is to prepare graphene/polyimide composite materials for use as bearing cage materials, improving the friction and wear performance of bearing cages.Design/methodology/approachThe oil absorption and discharge tests were conducted to evaluate the oil content properties of the materials, while the mechanical properties were analyzed through cross-sectional morphology examination. Investigation into the tribological behavior and wear mechanisms encompassed characterization and analysis of wear trace morphology in PPI-based materials. Consequently, the influence of varied graphene nanoplatelets (GN) concentrations on the oil content, mechanical and tribological properties of PPI-based materials was elucidated.FindingsThe composites exhibit excellent oil-containing properties due to the increased porosity of PPI-GN composites. The robust formation of covalent bonds between GN and PPI amplifies the adhesive potency of the PPI-GN composites, thereby inducing a substantial enhancement in impact strength. Notably, the PPI-GN composites showed enhanced lubrication properties compared to PPI, which was particularly evident at a GN content of 0.5 Wt.%, as evidenced by the minimization of the average coefficient of friction and the width of the abrasion marks.Practical implicationsThis paper includes implications for elucidating the wear mechanism of the polyimide composites under frictional wear conditions and then to guide the optimization of oil content and tribological properties of polyimide bearing cage materials.Originality/valueIn this paper, homogeneously dispersed PPI-GN composites were effectively synthesized by introducing GN into a polyimide matrix through in situ polymerization, and the lubrication mechanism of the PPI composites was compared with that of the PPI-GN composites to illustrate the composites’ superiority.Peer reviewThe peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-12-2023-0415

Effect of adding Urtica dioica–chopped fiber on load bearing, wear, fatigue, thermal stability, flammability, and water absorption behavior of rock dust dispersed vinyl ester composite

Effect of adding Urtica dioica–chopped fiber on load bearing, wear, fatigue, thermal stability, flammability, and water absorption behavior of rock dust dispersed vinyl ester composite

МЕТОДОЛОГИЯ ПРИНЯТИЯ ОПТИМАЛЬНЫХ РЕШЕНИЙ ПО УПРАВЛЕНИЮ ЖИЗНЕННЫМ ЦИКЛОМ ОБЪЕКТА КАПИТАЛЬНОГО СТРОИТЕЛЬСТВА С УЧЕТОМ КРИТЕРИЯ ПЫЛЕВОГО ЗАГРЯЗНЕНИЯ АТМОСФЕРНОГО ВОЗДУХА

Abstract. The existing approaches to decision-making in construction have two significant drawbacks. Firstly, they allow us to calculate the effectiveness of the options under consideration only for the object construction phase, without giving an idea of the decisions effectiveness taken at other life cycle stages. Secondly, the absence of an environmental safety criterion for a particular technology in the model reduces its universality and the adequacy of the decisions taken.&#x0D; The article proposes a new approach to management decision-making in construction as to the management of a capital construction object life cycle. A methodology has been developed for making optimal decisions on life cycle management, taking into account the criterion of atmospheric air dust pollution. In order to build the methodology, a block diagram of the formation of dust emissions into the atmosphere from temporary pollution sources at various stages was developed. The dust pollution values for works performed at various life cycle stages of a capital construction object were obtained experimentally. Based on the data obtained, the values of the given optimization criterion are determined for choosing the optimal solution for life cycle management, taking into account the criterion of atmospheric air dust pollution.&#x0D; Unlike the existing ones, the developed methodology allows, firstly, to calculate the effectiveness of the options under consideration not only for the construction stage, but also for the entire object life cycle. Secondly, the model introduces a criterion of environmental safety of the control solutions under consideration, quantified by the degree of dust pollution of atmospheric air.&#x0D; Subject of research: The processes of atmospheric air dust pollution when performing work at various stages of the capital construction object life cycle. &#x0D; Materials and methods: Theoretical and experimental methods for determining the concentration of dust pollution using the Ecologist program, based on the results of field dust pollution measurements and aerosol dispersed composition analysis.&#x0D; Results: A methodology for making optimal decisions on managing the capital construction object life cycle has been developed, including 5 stages.&#x0D; 1. Identification of work types that cause atmospheric air dust pollution.&#x0D; 2. Determination of fine dust concentration from each type of work.&#x0D; 3. Determination of the atmospheric air pollution indicator total value for the implementation of all control solutions (technologies) variants and for all capital construction object life cycle stages according to the proposed model.&#x0D; 4. Determination of given optimization criterion values for the implementation of all control solutions (technologies) variants and for all life cycle stages according to the proposed expression.&#x0D; 5. Selection of the control solution (technology) with the lowest given optimization criterion value.&#x0D; Conclusions: As a result of theoretical and practical research, a methodology has been created that allows, firstly, to calculate the effectiveness of the options under consideration not only for the construction stage, but also for the entire object life cycle. Secondly, the model introduces a criterion of environmental safety of the control solutions under consideration, quantified by the atmospheric air dust pollution degree.

Fischer–Tropsch synthesis over RuCo catalysts: An effect of ligands on the active phase properties and catalytic activity

High quality synthetic fuels could be obtained using the Fischer–Tropsch process. Development of new catalysts for this process is very important for the selective formation of fuel fractions. RuCo catalysts prepared bymodifyingthe support with ethylenediaminetetraacetic acid, urea, acetone azine,or citric acidwasinvestigated for the first timein orderto see theeffect oftheligand on the catalytic properties ofthebimetallic system. The catalysts were characterized by TEM, STEM, XRF, H2-TPR, NH3-TPD, and XPS. It was assumed that total acidity, reducibility, dispersion and atomic surface composition of the catalysts are dependent on the ligands used. The catalyst obtained after modification of Al2O3 with citric acid was characterized by low activity and the predominant formation of solid paraffins. The use of EDTA resulted in a highly active catalyst with highest selectivity to gasoline. Catalyst modified with acetone azine showed a high α (0.898) as well as a selectivity to the diesel fraction of 64.1 %, but average CO conversion of 23.3 %. The optimalcatalytic systemamongthosestudied was Ru/Co/Al2O3-urea.This system hada high conversionrateof 37.3 %anda selectivitytowardsC5+ hydrocarbons of 79.4 %.Thediesel fractionwas also produced in high yield.

Fabrication of SiC particle dispersed AZ91D magnesium alloy composite by injection molding method and their properties

Fabrication of SiC particle dispersed AZ91D magnesium alloy composite by injection molding method and their properties