Optimal Dispersion Research Articles

Preparation and Characterization of Carvedilol Solid Dispersion by Kneading Method

Solid dispersion using hydrophilic carrier is one of the approaches that has a potential to increase solubility, dissolution rate and consequently the oral bioavailability of poorly-water soluble drugs. In this study, class II drug "Carvedilol" (CVD) was used because of its poor solubility, it serves as a model drug that contributes to irregular dissolution and limited bioavailability. CVD: PVP K30 solid dispersion formulations SD1, SD2 and SD3 were prepared by kneading method at different weight ratios ,1:1; 1:2 and 1:4 respectively and evaluated for drug content, solubility and dissolution rate. Kneading method enhances the stability of drugs and suitable for processing thermolabile substances. The optimum solid dispersion ratio was characterized also for drug-carrier interaction by FTIR spectroscopy, and crystallinity by SEM and PXRD and compared with physical mixture and pure drug powder.
 The results showed that the solubility of carvedilol increased by increasing the proportion of PVP K30 used in the dispersion of the drug. On the other hand, dissolution study revealed a significant enhancement in the dissolution rate of the drug using solid dispersion compared to pure drug and physical mixture. X-ray diffraction of the solid dispersion suggest that the drug's transformation from crystalline to amorphous form may be responsible for the observed improvement in dissolving rate. The carvedilol solid dispersion improved the solubility and dissolution, which depend on the carrier concentration ratio. The dissolution of drugs increased with an increase in carrier content. The studies of PXRD, SEM, and FTIR revealed the amorphous nature of the drug in solid dispersion. The solid dispersion by kneading approach using PVP K30 as a carrier is a potential method for improving CVD's solubility and dissolution rate.

Studies of zinc content reduction using flake zinc powder in epoxy zinc-rich coatings

Purpose Epoxy zinc-rich coatings are widely used in harsh environments because of the long-lasting cathodic protection of steel surfaces. The purpose of this paper is to use flake zinc powder instead of the commonly used spherical zinc powder to reduce the zinc powder content. Design/methodology/approach In this paper, the authors have prepared an anticorrosive zinc-rich coating using a flake zinc powder instead of the conventional spherical zinc powder. The optimal dispersion of scaly zinc powder in zinc-rich coatings has been explored by looking at the surface and cross-sectional morphology and studying the cathodic protection time of the coating. Findings The final epoxy zinc-rich coating with 35 Wt.% flake zinc powder content was prepared using sand-milling dispersions. It has a similar cathodic protection time and salt spray resistance as the 60 Wt.% spherical zinc-rich coating, with a higher low-frequency impedance modulus value. Originality/value This study uses flake zinc powder instead of the traditional spherical zinc powder. This reduces the amount of zinc powder in the coating and improves the corrosion resistance of the coating.

Experimental study on nanoparticles-assisted low-salinity water for enhanced oil recovery in asphaltenic oil reservoirs

The purpose of this research is to look into the augmentation of silica nanoparticles (NPs) with low salinity (LowSal) brine for EOR. A series of analyses, including oil/water interfacial tension (IFT) and rock wettability tests were undertaken to determine an optimal dispersion to flood into a porous carbonate core with a defined pore size distribution. At 60 °C and 14.5 psi, the maximum drop (i.e., roughly 12.5 mN/m) in oil/water IFT by 0.3 wt.% brine occurred, but when 0.08 wt.% silica was added to the brine, the IFT reduced to 14.51 mN/m at 60 °C and 14.5 psi. The wettability analysis revealed a significant reduction in contact angle, from 142° to 72° and 59°, using 0.04 and 0.08 wt.% silica in LowSal brine, but the extent reduced by brine alone was insufficient. The results of rock pore size characterization were discussed in terms of the accomplishment of operating EOR in the porous medium in the presence of NPs. The addition of 0.08 wt. % silica to the injected brine resulted in an additional oil recovery of 16.3% OOIP as well as a significant shift in the endpoints/cross-points of the oil/water relative permeability curves. The findings of this research might help improve oil recovery from asphaltenic oil reservoirs or, more environmentally friendly, remediate petroleum crude-oil polluted soil.

Fresh and hardened performance of concrete enhanced with graphene nanoplatelets (GNPs)

This paper presents an investigation into the fresh and hardened properties of concrete enhanced with graphene nanoplatelets (GNPs). GNP dispersions were prepared using wet dispersion techniques and the influence of various factors on dispersion quality, such as mixing/dispersion methods, sonication time/intensity and GNP concentrations were evaluated. Sedimentation photos and zeta potential analysis were used to assesses the stability of GNP dispersions and determine optimal dispersion conditions for incorporation of GNPs into the concrete specimens. Further, advanced X-ray diffraction (XRD) techniques were used to determine the crystallographic structure of GNPs and a scanning electron microscope (SEM) revealed information about the external morphology (texture), composition and the orientation of the nano materials. Various GNP concentrations were explored including: 0.0, 0.05, 0.1, 0.15, 0.20, 0.25, 0.3 and 0.35 wt % and their effects on workability, apparent density, compressive strength and flexural strength were evaluated. The results suggested that the optimal concentration of GNP was 0.25 wt% which increased compressive and flexural strength of concrete by up to 20.7% and 8.8%, respectively. However, the addition of 0.25 wt% GNPs decreased workability by more than 50% compared to control specimens. Further, apparent density of concrete specimens was not affected by adding GNPs.

Advanced 3D printing of graphene oxide nanocomposites: A new initiator system for improved dispersion and mechanical performance

The integration of nanoparticles, such as Graphene Oxide (GO), with photo-curable polymers in 3D printing has garnered significant interest in recent years due to the potential to create functional nanocomposite materials. This study explores the challenges of achieving optimal dispersion of GO nanoparticles within the polymer matrix and the crucial role of photoinitiators in overcoming these limitations. Traditional photoinitiators, like TPO, commonly used for GO/polymer resins, have raised concerns about high toxicity and limited sensitivity to visible light, prompting the need for alternative initiating systems. In this research, we propose a two-component initiator system based on bis-(4-t-butylphenyl)iodonium hexafluorophosphate and photosensitizer N-{4-[(E)-2-(pentafluorophenyl)ethenyl]phenyl}-2,1,3-benzothiadiazol-4-amine (IOD/PS1) as a promising solution. This new initiating system not only ensures a more environment-friendly resin but also exhibits enhanced polymerization kinetics and compatibility with GO nano fillers. This study investigated the effect of the addition of nano-GO on the kinetics of the radical photopolymerization process, 3D printing, and final mechanical and thermal properties of the received products. TPO and PEGDA/H2O were used as reference systems. In addition, a new two-component initiator system was synthesized, which is an interesting alternative to the commercial TPO initiator that is widely employed in additive techniques. This publication presents the research procedure involving various techniques: real-time FTIR and photoreology. In addition, the possibility of creating three-dimensional structures from the newly developed photo-curable resins was verified. Finally, the morphologies and mechanical properties of the resulting 3D structures were compared. Within the work, we demonstrate the advantages of the two-component initiator in achieving uniform distribution of GO and fabricating high-quality materials. By applying IOD/PS1 initiating system we facilitated a more controlled and efficient polymerization process, reducing shrinkage-induced stresses and enhancing interlayer bonding. The result was the fabrication of high-quality, well-dispersed materials with tailored properties suitable for various applications, particularly in the biomedical field.

The Development of Fe3O4-Monolithic Resorcinol-Formaldehyde Carbon Xerogels Using Ultrasonic-Assisted Synthesis for Arsenic Removal of Drinking Water.

Inorganic arsenic in drinking water from groundwater sources is one of the potential causes of arsenic-contaminated environments, and it is highly toxic to human health even at low concentrations. The purpose of this study was to develop a magnetic adsorbent capable of removing arsenic from water. Fe3O4-monolithic resorcinol-formaldehyde carbon xerogels are a type of porous material that forms when resorcinol and formaldehyde (RF) react to form a polymer network, which is then cross-linked with magnetite. Sonication-assisted direct and indirect methods were investigated for loading Fe3O4 and achieving optimal mixing and dispersion of Fe3O4 in the RF solution. Variations of the molar ratios of the catalyst (R/C = 50, 100, 150, and 200), water (R/W = 0.04 and 0.05), and Fe3O4 (M/R = 0.01, 0.03, 0.05, 0.1, 0.15, and 0.2), and thermal treatment were applied to evaluate their textural properties and adsorption capacities. Magnetic carbon xerogel monoliths (MXRF600) using indirect sonication were pyrolyzed at 600 °C for 6 h with a nitrogen gas flow in the tube furnace. Nanoporous carbon xerogels with a high surface area (292 m2/g) and magnetic properties were obtained. The maximum monolayer adsorption capacity of As(III) and As(V) was 694.3 µg/g and 1720.3 µg/g, respectively. The incorporation of magnetite in the xerogel structure was physical, without participation in the polycondensation reaction, as confirmed by XRD, FTIR, and SEM analysis. Therefore, Fe3O4-monolithic resorcinol-formaldehyde carbon xerogels were developed as a potential adsorbent for the effective removal of arsenic with low and high ranges of As(III) and As(V) concentrations from groundwater.

A Multi-Channel Frequency Router Based on an Optimization Algorithm and Dispersion Engineering.

Integrated frequency routers, which can guide light with different frequencies to different output ports, are an important kind of nanophotonic device. However, frequency routers with both a compact size and multiple channels are difficult to realize, which limits the application of these frequency routers in nanophotonics. Here, a kind of bandgap optimization algorithm, which consists of the finite element method and topology optimization, is proposed to design a multi-channel frequency router. Channels supporting photonic edge states with different frequencies are built through the synthetic dimension of translational deformation. Due to the help of the developed optimization algorithms, the number of channels and output ports can be increased up to nine while maintaining ultracompact device size. The device operates within a working band of 0.585-0.665 c/a, corresponding to 1.504-1.709 μm when the lattice constant is set as 1 μm, covering the telecom wavelength of 1.55 μm. The average crosstalk is about -11.49 dB. The average extinction ratio is around 16.18 dB. Because the bus of the device can be regarded as a part of a topological rainbow, the results show that the structure is robust to fabrication errors. This method is general, which can be used for different materials and different frequency ranges. The all-dielectric planar configuration of our router is compact, robust, and easy to integrate, providing a new method for on-chip multi-channel broadband information processing.

Memory optimal dispersion by anonymous mobile robots

Consider a team of k≤n autonomous mobile robots initially placed at a node of an arbitrary graph G with n nodes. The dispersion problem asks for a distributed algorithm that allows the robots to reach a configuration in which each robot is at a distinct node of the graph. If the robots are anonymous, i.e., they do not have any unique identifiers, then the problem is not solvable by any deterministic algorithm. However, the problem can be solved even by anonymous robots if each robot is given access to a fair coin which they can use to generate random bits. In this setting, it is known that the robots require Ω(logΔ) bits of memory to achieve dispersion, where Δ is the maximum degree of G. On the other hand, the best known memory upper bound is min{Δ,max{logΔ,logD}} (D = diameter of G), which can be ω(logΔ), depending on the values of Δ and D. In this paper, we close this gap by presenting an optimal algorithm requiring O(logΔ) bits of memory.

Influence of dispersion of fibrillated cellulose on the reinforcement of coated papers

The use of cellulose micro/nanofibrils (CMNFs) as reinforcement paper additive at industrial scale is delayed due to inconsistent results, suggesting a lack of proper consideration of some key parameters. The high influence of fibrillated nanocellulose dispersion has been recently identified as a key parameter for paper bulk reinforcement but it has not been studied for surface coating applications yet. This paper studies the effect of CMNF dispersion degree prior to their addition and during mixing with starch on the reinforcement of paper by coating. Results show that this effect depends on the type of CMNFs since it is related to the surface interactions. For a given formulation, a correlation is observed between the CMNF dispersion and the CMNF/starch mixing agitation with the rheology of the coating formulation which highly affects the paper properties. The optimal dispersion degree is different for each nanocellulose, but the best mechanical properties were always achieved at the lowest viscosity of the coating formulation. In general, the initial state of the nanocellulose 3D network, influences the mixing and smooth application of the coating and affects the reinforcement effect. Therefore, the CMNF industrial implementation in coating formulations will be facilitated by the on-line control of formulations prior to their surface application.

Quantitative Analysis of Spatial Heterogeneity and Driving Forces of the Urban Spatial Structure’s Development Level Based on Multi-Source Big Data: A Case Study of Beijing, China

Many developed cities in the world put forward a spatial development strategy in their construction planning. Analyzing the development level of the urban spatial structure and the influence of driving factors has become a hot topic. Based on 709,232 points of interest data in Beijing, China, this paper integrates nighttime light data and population density data to select eight key driving factors from three perspectives: urban function configuration, economic activity intensity and population spatial distribution. Geodetector is used to optimize data discreteness and highlight the spatial heterogeneity of the development level. We use the technique for order of preference by similarity to ideal solution (TOPSIS) model improved with the entropy weight method to grade the spatial differentiation characteristics of the comprehensive development level. The driving factors and their effects on space are further discussed using Geodetector. The results are as follows: (1) The quartile method can achieve the optimal dispersion of all urban functions. The standard deviation can achieve the optimal dispersion of economic activity intensity and population spatial distribution; (2) A comparison with the “Beijing Urban Master Plan (2016–2035)”, finds that the optimized evaluation system can effectively reflect the spatial heterogeneity of urban spatial structure development. It verifies the rationality of the evaluation methods and factors; (3) The driving force of the population under single-factor driving is 0.8428. The dual-factor driving force with population participation ranges from 0.8992 to 0.9550. The results of the study are significant and reflect the prominent role of population on the development level of spatial structure in Beijing. This paper aims to provide a new idea for the study of the interior space planning of large inland cities.

Material characterization of polymer nanocomposites for aerospace applications

Nanocomposites have been used as suitable substitutes for metal matrices and alloys for quite some time. In industrial applications, carbon fiber reinforced polymers (CFRP) and other fiber reinforced polymers (FRP) are more prevalent as compared to polymers reinforced with one dimensional nanofillers. It becomes important to analyze the effects on the mechanical properties of polymer matrix when reinforced with nanofillers. The nanocomposites are prepared using epoxy resin as the polymer matrix. Two nanofillers, namely carbon nanotubes (CNT) and halloysite nanotubes (HNT) are used to compare the impact of each on the polymer matrix. Three different weight percentages for each nanofiller composite are fabricated: 0.5 wt%, 1 wt% & 1.5 wt% for CNT and 1 wt%, 5 wt% & 10 wt% for HNT is considered. The microstructural characterization through Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD) provided an in-depth understanding of the dispersion of nanofillers in the polymer matrix and the quality of its fabrication. The images obtained from the SEM show the presence of micro voids and some agglomerations in the specimens. The XRD plots with peak broadening confirm the smaller size of crystallite in nanocrystalline materials of the specimens. The mechanical characterization, which includes hardness, tensile and flexural showed the effect of nanofillers in the epoxy. However, it can be concluded that the application of 1 wt% nanofillers leads to an optimum dispersion and improved the polymer mechanical capabilities. A fractography analysis can be considered as a future scope of this study.

Preparations and characterizations of effervescent granules containing azithromycin solid dispersion for children and elder: Solubility enhancement, taste-masking, and digestive acidic protection

Azithromycin, a macrolide antibiotics, is one of the frequently used drugs in the children and elder. However, due to these population difficulty in swallowing and inefficient absorption, and azithromycin inherent poor solubility, bitter taste, and instability in the stomach acidic condition, it is a challenge to reach high oral bioavailability of this drug. To overcome these issues, we developed and characterized the effervescent granules containing azithromycin solid dispersion. Firstly, the solid dispersion was prepared, employing both wet grinding and solvent evaporation methods, with different types/amounts of polymers. The optimal solid dispersion with β-cyclodextrin at a drug:polymer ratio of 1:2 (w/w), prepared by the solvent evaporation method, significantly enhanced the azithromycin solubility 4-fold compared to the free drug, improved its bitterness from “bitter” to “normal”, possessed intermolecular bonding between the drug and polymer, and transformed the azithromycin molecules from crystalline to amorphous state. Secondly, the effervescent granules incorporating the solid dispersion were formulated with varied excipients of sweeteners, gas-generators, pH modulators, and glidants/lubricants. The optimal formula satisfied all the properties stated in the Vietnamese Pharmacopoeia. In summary, the final effervescent granules product could be further investigated in in-vivo and in clinical settings to become a potential azithromycin delivery system with high bioavailability for the children and elder.

Numerical Investigation of Conductivity Additive Dispersion in High‐Power and High‐Energy NMC‐Based Lithium‐Ion Battery Cathodes: Application‐Based Guidelines

Herein, guidelines are provided for the dispersion of conductivity additive in nickel‐manganese‐cobalt‐oxide‐based lithium‐ion battery (LIB) cathodes with respect to its influence on electrochemical performance. The contrasting design strategies and operating conditions applicable to high‐power and high‐energy cathodes lead to significant differences in performance limiting factors for the respective microstructures. Hence, a generalization of the optimum dispersion of the conductivity additive that enhances cell performance in all cases is not possible. In this work, four distinct distributions of conductivity additive agglomerate/aggregate sizes resulting from varying mixing conditions are investigated with respect to their compatibility with cathode microstructures intended for different LIB applications with the help of spatially resolved electrochemical simulations. It is found that in the case of high‐power cathodes, wherein ionic transport is the dominant performance limiting factor, a more significant proportion of agglomerates that are bigger in size leads to improved diffusion and intercalation conditions. Conversely, in the case of high‐energy electrodes wherein the conductivity additive content is minimized, a larger fraction of smaller aggregates, produced by the fragmentation of the agglomerates during the mixing process are essential to ensure sufficient electrical conductivity.

Synthesis ofSMA‐PEGhyperdispersant and its stabilization mechanism for carbon black

AbstractIn this paper, four comb hyperdispersants (SMA‐MPEGA) with different side chain lengths and side chain densities were prepared by the amide coupling reaction of styrene‐maleic anhydride (SMA) copolymer and methoxypolyethylene glycol amine (MPEGA). The dispersion behavior of SMA‐MPEGA on carbon black was investigated by rheology and water contact angle measurement. The combined technologies of transmission electron microscopy, digital light synthesis, zeta potential, surface tension and UV–Vis have been successfully used to reveal the stability mechanism of SMA‐MPEGA. The SMA3000‐MPEGA1000 with a molar ratio of styrene to maleic anhydride of 3:1 and the molecular weight of side chain PEG of 1000 has the optimum carbon black dispersion. The results of the effect of dispersant structure on its dispersion performance reveal that the stable adsorption of dispersant on the surface of carbon black is the key to obtaining a space or electrostatic repulsion stabilizing role.

Characteristics of Epoxy Composites Containing Carbon Nanotubes/Graphene Mixtures.

The paper considers the development of fillers representing mixtures of carbon nanotubes and graphene materials (graphene oxide and graphene nanoplatelets) in different mass ratios to modify epoxy resin. The graphene type and content effect on the dispersed phase particle effective sizes-both in aqueous suspensions and the resin-was analyzed. Hybrid particles were characterized by Raman spectroscopy and electron microscopy. The composites containing 0.15-1.00 wt.% CNTs/GO and CNTs/GNPs were thermogravimetrically analyzed, and their mechanical characteristics were determined. SEM images of the composite fracture surfaces were acquired. Optimal dispersions containing 75-100 nm particles were obtained at the CNTs:GO mass ratio of 1:4. It was shown that the CNTs can be located between the GO layers and on the GNP surface. The samples containing up to 0.2 wt.% CNTs/GO (at 1:1 and 1:4 ratios) were stable when heated in air up to 300 °C. For 0.15-0.20 wt.% CNTs/GO (at 1:1 ratio), the tensile strength and modulus of the composite increased by 84-88 and 40%, respectively. The increase in the strength characteristics was found to occur due to the interaction of the filler layered structure with the polymer matrix. The obtained composites can be used as structural materials in different fields of engineering.

Evaluation and selection of passion fruit progenies resistant to collar rot disease

The objective of this work is to evaluate and select backcrosses of passion fruit progenies resistant to soil diseases. This selection contributes to the improvement of the passion fruit genetic improvement program. A cross of the interspecific hybrid UNEMAT 124-3 resistant to Fusarium solani was carried out. The hybrid arose from crossing the resistant species P. nitida with a commercial cultivar of P. edulis. P. edulis, cultivar BRS Sol do Cerrado, was a recurrent parent. The BC1 resistance tests were evaluated twice. The first test was carried out with BC1 adducts that are in the field; for this, clone seedlings were produced from cuttings of each plant for the resistance test. The second test comprised inoculation directly into BC1s that were planted in pots without replications. In addition, clones of P. nitida and HI were used as a positive (resistant) control and clonal seedlings of P. edulis as a negative (susceptible) control. The evaluation of resistance of the genotypes to F. solani was quantified considering ten resistance variables. In the first trial with plants from cuttings, it was possible to identify the BC1s 02, 14, and 24 as resistant to F. solani. In the second trial with Passiflora spp. seedlings, considering the results of UPGMA, hierarchical methods of torch optimization and graphical dispersion per genotype considering the importance of characters, it was possible to identify the BC1s 25, 26, 27, 28, 31, 43, 45, 48, 53, 57, 58, 61, 63, 66, 68, 71, 72, 73, 74, 80, 81, 83, 84, 86, and 87 as resistant. These should be selected to continue the passion fruit improvement program

Quantifying factory-scale CO2/CH4 emission based on mobile measurements and EMISSION-PARTITION model: cases in China

Development of the measurement-based carbon accounting means is of great importance to supplement the traditional inventory compilation. Mobile CO2/CH4 measurement provides a flexible way to inspect plant-scale CO2/CH4 emissions without the need to notify factories. In 2021, our team used a vehicle-based monitor system to conduct field campaigns in two cities and one industrial park in China, totaling 1143 km. Furthermore, we designed a model based on sample concentrations to evaluate CO2/CH4 emissions, EMISSION-PARTITION, which can be used to determine global optimal emission intensity and related dispersion parameters via intelligent algorithm (particle swarm optimization) and interior point penalty function. We evaluated the performance of EMISSION-PARTITION in chemical, coal washing, and waste incineration plants. The correlations between measured samples and rebuilt simulated ones were larger than 0.76, and RMSE was less than 11.7 mg m−3, even with much fewer samples (25). This study demonstrated the wide applications of a vehicle-based monitoring system in detecting greenhouse gas emission sources.

Exploring optimal dispersion process parameters for fabrication of graphene-reinforced cement composites

Graphene and its derivatives have been studied as nano-reinforcement in cement-based composites to improve their mechanical, transport and durability characteristics. However, the agglomeration effect due to the strong van der Waals force between graphene sheets makes the uniform dispersion difficult and limit the efficacy of graphene. The goal of this paper is to determine an optimal dispersion process for incorporating graphene nanoplatelets (GNPs) into cement-based composites. Surfactant-assisted sonication was used for the dispersion of graphene sheets. The effects of sonication amplitude, sonication duration, sample volume, surfactant type, and surfactant-to-GNP ratio on the dispersion performance were studied. As for the surfactant type, two polycarboxylate superplasticizers, two ionic surfactants, and one non-ionic surfactant were considered. Taguchi method of experimental design with an orthogonal array of L25 was employed to minimize the number of experiments needed to assess the effects of selected factors on the dispersion process. The average particle size, UV–vis absorbance, residual absorbance after 24 h, and zeta potential were measured through dynamic light scattering and UV–vis spectroscopy tests. Two multi-criteria decision making methods, namely Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS) and Principle Component Analysis (PCA) methods, were then employed to determine the optimal values of experimental factors for the dispersion. Finally, graphene-mortar composites were fabricated using two different surfactants and the properties of the developed composites were evaluated. The results indicates a 32% and 52% improvement in compressive strength and volume of permeable voids of graphene-enhanced mortar composites.

Impact strength and fracture behavior of Halloysite nanotube (HNT)-modified carbon fiber-reinforced polymers (CFRPs) based on the electrophoretic dispersion (EPD) process

Because particles that accumulate without movement can lead to a deposition gradient, the formation of a stable suspension is essential for the electrophoretic dispersion (EPD) process. The hydrophobic properties of Halloysite nanotubes (HNTs) were easily dispersed in many nonpolar polymers without further deformation steps. However, the uniform dispersion of HNTs in aqueous solutions is a pre-EPD process task. The zeta potential controls the main parameters of EPD processes, such as the density of deposits, particle orientation and velocity, and repulsive interactions between particles, which determine the stability of the suspension. In this study, the solution stability range for the addition of nanoparticles was measured and the optimal dispersion range was determined. In addition, an HNT-reinforced composite material was created by determining the optimal dispersion stability range of HNT, and the impact strength and fracture mechanism of the interface were analyzed. The solution stability and dispersion were the best between pH 6.6 and 6.8, and the highest impact strength was confirmed at 0.7 wt%. The HNT confirmed the interfacial dispersion of the EPD-fibers using scanning electron microscopy and dispersive X-ray spectroscopy (SEM-EDS).

Influence of different dispersants on the quality and stability of aqueous quinacridone magenta pigment dispersion for ink‐jet applications

AbstractThe stability of water‐based pigment dispersions is a key factor in determining their utility in ink‐jet applications, and the appropriate choice of dispersant plays a special role. Among the pigment formulations tested to date, literature data on magenta pigments are very limited. Thus, the goal of this work was to study the influence of the type and loading of dispersants on the quality and stability of quinacridone magenta pigment dispersions. Three different commercially available dispersants were tested: (1) a cationic styrene‐maleic anhydride copolymer, (2) an anionic polyacrylate, and (3) a nonionic alkyl ethoxylate. Pigment and dispersing agents were analysed using the Fourier Transform–infrared method. The stability of pigment dispersions was determined by comparative studies of changes in the pigment particle size, viscosity, pH, filtration time, optical density and gloss during the accelerated ageing test. Moreover, Turbiscan AGS and LUMiFuge analysers were used for evaluations of the instability of the dispersions. The properties of each dispersing agent affected the performances of the different dispersants. The highest stability for the pigment formulations was provided using the nonionic dispersant (small particle size, < 60 nm; the lowest viscosity < 60 mPa·s at the optimal dispersant content; favourable results of the filtration test; the highest pigment dispersability, proven by optical density and gloss). The Turbiscan AGS and LUMiFuge results indicated that the stability of all tested quinacridone magenta pigment dispersions was excellent (Turbiscan Stability Index values below three, and no significant differences in transmission profiles, respectively). However, it was found that the measurement results were influenced by the viscosity of the formulations.