Papers by Keyword: Dispersion

Abstract: Pantograph slide materials demand excellent mechanical and electrical properties for rail applications. Carbon-copper (C-Cu) composites combine the high electrical conductivity of copper with lightweight and wear-resistant traits of carbon. Using palm kernel shells (PKS), a palm oil industry by-product, promotes sustainability but presents challenges in achieving uniform distribution and performance retention. This study examined PKS and graphite as carbon sources in C-Cu composites enhanced with carbon nanotubes (CNT), focusing on optimising mechanical and electrical properties for pantograph slides. However, CNT is known for its difficulty in achieving optimum dispersion in composites, as strong van der Waals forces cause aggregation, uneven distribution, and porosity, thereby reducing the electrical and mechanical properties. Balancing carbon content, CNT reinforcement, copper, and resin matrix is crucial to prevent conductivity loss and structural weaknesses. Varied CNT content (1wt% to 5wt%) was analysed for its impact on hardness, transverse rupture strength (TRS), and electrical resistivity of the C-Cu composite. Fabrication involved material mixing, cold pressing, warm compaction (150°C, 490 kN, 5 minutes), and post-baking process (250°C, 4 hours). The 2 wt% CNT sample achieved superior results, including 102.5 HRR hardness, 37.63 MPa TRS, and 32 µΩ.m resistivity before post-baking, due to excellent CNT dispersion. Post-baking enhanced bonding and mechanical properties but raised resistivity by altering conductive pathways. Poor dispersion of CNT at contents more than 3 wt% led to agglomeration and inferior properties. The findings highlight the critical role of CNT dispersion and the post-baking process in achieving optimal composite performance to maximise CNT potential. These results are comparable to commercial pantograph slides, contributing to the development of high-performance materials for rail applications.

Abstract: Imidazole is an aromatic and alkaloid diazole that shows prominent anticancer properties. Regulating the imidazole compound into nano-drugs in the size range 10-200 nm enhances the effectiveness of imidazole as an anti-cancer agent, thus enhancing therapeutic potential. In this study, imidazole nano drug dispersion was prepared using the re-precipitation method. The dispersion of various imidazole derivative compounds, namely 4-(4,5-diphenyl-1H-imidazol-2-yl)-2-methoxyphenol (Vanilin), 2-(4-Methoxyphenyl)-4,5-diphenyl-1H-imidazole (O-Me), 2,4,5-Triphenylimidazole (Benzaldehid) and 2-(4-nitrophenyl)-4,5-diphenyl-1H-imidazole (Nitro) were screened. The dispersion stability was evaluated in a mimic biological environment using phosphate buffer saline (PBS) for 24 hours, and the size of the nanodrugs was determined. The results showed that 4-(4,5-diphenyl-1H-imidazol-2-yl)-2-methoxyphenol had the best size of 203 nm, and no aggregation was observed even after 24h. This result indicates that 4-(4,5-diphenyl-1H-imidazol-2-yl)-2-methoxyphenol (Vanilin) meets the requirement of enhanced permeability retention (EPR) effect and is a prominent candidate as an effective anti-cancer agent.

Abstract: This scientific study presents experimental results of particle agglomeration and dispersing processes under various physicochemical conditions, focusing on the effects of temperature, particle concentration, and medium viscosity. Using numerical approaches and experimental data, patterns describing the changes in agglomeration rate and the features of dispersing system stability were identified. The key findings of the research include: the influence of temperature on agglomeration, high particle concentration, medium viscosity, dispersion under low particle concentration conditions. It is noteworthy that the results also confirm an exponential dependence of the agglomeration rate on temperature. However, at high particle concentrations, this effect is mitigated by the dominance of interparticle interactions, such as Van der Waals forces and electrostatic effects. Furthermore, in systems with low particle concentration and elevated temperature, agglomeration processes significantly slow down, indicating improved dispersing stability. The study opens new perspectives for controlling particle agglomeration and dispersing based on temperature, concentration, and the physical properties of the medium. The obtained data can be useful for improving existing technologies and developing new ones in areas where controlling the behavior of dispersed systems is essential.

Abstract: This comparative study explored the dynamic mechanical characteristics and resistance to corrosion of four distinct nanofillers; MXenes, Graphene Nanoplatelets (GNPs), Carbon Nanotubes (CNTs), and Halloysite Nanotubes (HNTs) within epoxy composites at low loading concentrations (0.1 wt.%). The study assessed the influence of nanofiller on dynamic mechanical properties, while Open Circuit Potential (OCP) and Tafel analyses were used to evaluate corrosion resistance of the coated samples. The dispersion analysis was carried out using both UV-Vis spectrophotometry and scanning electron microscope Scanning electron Microscopy (SEM) technique. It was observed, there is notable decrease in storage modulus arises from poor nanofiller dispersion within the matrix and limited interaction between nanofillers and polymer chains. The incorporation of nanofillers typically leads to an increase in T_g, as observed with the highest T_g value (83.79 °C) in the GNPs sample, indicating restricted molecular motion and reduced free volume due to filler dispersion, resulting in enhanced crosslinking and significant changes in polymer chain dynamics. The OCP curve significantly decreased for the MXenes/epoxy coating (from 0.1827 V to 0.0454 V), indicating increased coating stability and better corrosion resistance behaviour. However, further processing improvement is needed to enhance the dispersibility of MXenes in the polymer matrix, as shown by SEM images showing agglomerates within the nanocomposite sample.

Abstract: Nanotechnology has been the prime approach over the last several decades including in scaling prevention. There has been a flurry of activity in incorporating nanoparticles (NPs) with scale inhibitors (SI) to help mitigate the scales’ growth at the early stage before it worsens. However, despite the increasing use of nanoparticles in industry, reservoir complexity such as salinity and heterogeneity have significantly impacted the nanoparticles' performance in the medium. The nanoparticles' repulsive forces are reduced when brine salinity is present, resulting in flocculation and coagulation of nanoparticles in suspension and phase separation. However, the stability and dispersion of nanoparticles may be improved by altering their characteristics by coating them with a surfactant for a particular application. This can be done by introducing a surfactant in the nanoparticle suspension. Herein, this paper aims to study the dispersion and stability of different types of NPs and their performance in Sodium Dodecyl Sulfate (SDS) surfactant solution. Results obtained proved that carbon-based NPs (graphene oxide (GO) and multi-walled carbon nanotube (MWCNT)) showed an excellent zeta potential measurement up to -116 mV when these NPs were dispersed in SDS solution. This surfactant has significantly improved the NPs stability by increasing electrostatic repulsion between the NPs while reducing the average size of agglomeration.

Abstract: Boron Nitride (BN) filler was modified by an ion beam surface treatment to enhance dispersibility to polar solvent and bond strength with epoxy. Surface treatment of the fillers was conducted by Ion Assisted Reaction (IAR), in which Ar⁺ ion beam is irradiated on the filler surface with energy of 1keV, dose varied from 1x10¹⁴ ~ 5x10¹⁶ Ar⁺ ions/cm² by using Cold Hollow Cathode type ion source and oxygen gas 5-10ml/sec. After the surface treatment, the BN powder were spontaneously dispersed into polar solvent in a visual observation which means the modified surface was changed from hydrophobic to hydrophilic, and the powder were easily mixed with a viscous epoxy resin until 40wt% without thinner (a gelation phenomenon with easy blending into the epoxy resin), but the untreated powder exhibits difficulty in mixing with epoxy resin without the thinner. XPS analysis showed oxygen functional groups (B-ON, BN, etc.) were formed on the surface of BN. It was confirmed the surface modification has a high filling ability of the BN filler with binder and better adhesion with epoxy resin compared to the untreated BN filler.

Abstract: A deep understanding on the intermixing of components in hybrid yarn or composite structures is decisive in order to develop hybrid structures with desired properties. This paper presents the development of a versatile procedure for the determination of the degree of fiber mixing in yarns and composites based on microscopy images auto-segmented by a neural network. The procedure is based on the quantification of blend irregularity values and blend homogeneity. For this purpose, functions of spatial point patterns analysis have been used to investigate the blend uniformity of yarn and composite cross sectional areas. The results show that the trained neural network model for segmentation of images has an accuracy of 92 %, indicating that the method is capable of accurately assessing the location of fibers in hybrid struc-tures. The results of the spatial point patterns analysis reveals a correlation between the blend value and the properties of yarns and composites. The proposed method provides a fast and reliable way to evaluate the hybrid structures, which could be used as a tool for quality control and process optimization.

Abstract: Both the air-water dispersion coefficient and the air-nanofluid (CuO) dispersion coefficient were studied and measured in a double-pipe heat exchanger. Pumping air into a tank fitted with a Rushton turbulent impeller resulted in gas-liquid dispersion. In order to test the effects of varying operating conditions on the air-water and air-nanofluid dispersions, they were heated and pumped into the tube of a double-pipe heat exchanger. Reynolds numbers of Re_c= 4750-13100 on the shell side and Re_h=19900-64000 on the tube side were used to get the total heat transfer coefficient (U_o). The dispersion in the hot fluid tank was achieved by combining the two-phase fluids using a Rushton turbine impeller. It was discovered that the conscious phase saw a significant drop in the heat transfer coefficient when the air bubbles dissipated. Because the impeller's agitation speed affects the rate at which air bubbles are broken, the heat transfer coefficient in the case of dispersion rises as Re_h and Re_c rise. For all examined parameter values, CuO nanofluid showed significant heat transfer improvement. The heat transfer rate of gas-liquid dispersion increases by nanofluid by as much as 135.5% compared to gas-liquid dispersion which is considered the first attempt for heat transfer enhancement of two phase flow (gas-liquid dispersion) using Nano fluid.

Abstract: The effect of the quantitative and qualitative composition of mixed binders on the physical and mechanical properties of cement compositions has been experimentally established. A cement stone with a different amount and dispersion of mineral fillers was considered. The research results showed that the plastic strength of the hardening system depends on its initial composition. The defects embedded in the material during its technological processing into the product determine the local stress-strain state of the structure, the nature of cracking and the fracture surface. The effect of technological damage on the mechanical characteristics and the nature of cracking of cement compositions are shown. The possibility of reducing the material consumption of construction materials by 15-21 wt.% due to the use of fillers that are optimal in appearance and quality composition has been proved.

Abstract: The article considers methods of manufacturing non-toxic films of a given color that meet technological requirements. The problem of reducing the shrinkage of the colored polymer in the casting mould during cooling and maintaining its technical characteristics is experimentally solved. To this end, the influence of the nature of pigments on the degree of polymer coloring is studied, and ways to improve the quality of color are investigated. The object of the study was selected pigment concentrate based on high pressure polyethylene brand 15803-003. The pigment has chosen technical carbon grades N220, P803. Surfactants were modifying additives. Tests of samples to determine the light fastness of dye, migration resistance, the number of agglomerates of pigments, toughness and strength, physical and mechanical properties showed that the most effective additive to improve the coloring properties of soot pigment brand N220 and improve the appearance of finished products introduced into the superconcentrate calcium stearate, which at the stage of mixing in the extruder acts as a surfactant and prevents the adhesion of the pigment and the formation of agglomerates in the polymer melt.