Aqueous processing of SiC green sheets I: Dispersant

Poly(ethylene imine) (PEI) has been used as a dispersant for tape casting of SiC powders in aqueous media. The stability of SiC suspensions was studied and characterized in terms of zeta potential, sedimentation, adsorption, and rheology measurements. Zeta potential studies showed that the particle surface was negatively charged in the absence of PEI in the pH 2.5–13 ranges. Adsorptions of PEI increased the zeta potential and led to the shift of isoelectric point from pH 2.4 to pH 10.5. Sedimentation study showed that, in the absence of PEI, SiC slurries were stable around pH 6, while, in the presence of PEI, stabilization could be achieved at a condition of saturated adsorption (1.07 mg/m2) and was related to the high-;affinity adsorption in the pH = 10.5–11.5 range. The rheological measurements showed that SiC slurries (50 vol%) were well stability with slight thixotropical behavior. Finally, the best conditions to obtain a homogeneous stable slurry with high powder loading suitable for tap casting were determined.

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Determining the Lanthanum Chromite Zeta Potential in Aqueous Media

Materials Science Forum ◽

10.4028/www.scientific.net/msf.660-661.1145 ◽

2010 ◽

Vol 660-661 ◽

pp. 1145-1150 ◽

Cited By ~ 2

Author(s):

Luiz Fernando Grespan Setz ◽

Sonia Regina Homem de Mello-Castanho

Keyword(s):

Fine Particles ◽

Aqueous Media ◽

Tape Casting ◽

Slip Casting ◽

Lanthanum Chromite ◽

Zeta Potentials ◽

Liquid Suspension ◽

Present Complex ◽

The Stability ◽

Processing Techniques

Lanthanum Chromite may used as interconnect for SOFC’s applications due its particular intrinsic properties as stability in both oxidant and reducing environments and electrical conductivity. However to manufacture these devices that generally present complex shapes as grooved plates and fine pipes, they are necessary the use of the conformation techniques such as screen printing, slip casting, tape casting, extrusion moulding, etc. that are related with colloid processing. Independent of the processing techniques chosen the control of the suspension conditions is important to obtain reproducibility and homogeneous products as final result. In this sense, all contribution to understand the behaviour of the LaCrO3 fine particles in liquid suspension as the surface state using the Zeta’s Potential concepts may supplies information by the forecast of the behaviour during the shaped processing. The aqueous suspensions behaviour was studied utilizing doped lanthanum chromite powders, attained by combustion synthesis. The eletrophoretic mobility measurements of particles in suspension, prepared with the different conditioned powders were made. The electrolyte compositions as function of the pH varying from 2 to 12 were tested. The Zeta potentials and the stability conditions for stable suspensions prepared were determined. The viscosity curves are also appraised.

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Surface characterization of nanoparticles using near-field light scattering

Beilstein Journal of Nanotechnology ◽

10.3762/bjnano.9.114 ◽

2018 ◽

Vol 9 ◽

pp. 1228-1238 ◽

Cited By ~ 5

Author(s):

Eunsoo Yoo ◽

Yizhong Liu ◽

Chukwuazam A Nwasike ◽

Sebastian R Freeman ◽

Brian C DiPaolo ◽

...

Keyword(s):

Light Scattering ◽

Zeta Potential ◽

Surface Characterization ◽

Colloidal Stability ◽

Near Field ◽

Particle Surface ◽

Superparamagnetic Iron Oxide ◽

Scattering Intensity ◽

Potential Applications ◽

Poly Ethylene

The effect of nanoparticle surface coating characteristics on colloidal stability in solution is a critical parameter in understanding the potential applications of nanoparticles, especially in biomedicine. Here we explored the modification of the surface of poly(ethylene glycol)-coated superparamagnetic iron oxide nanoparticles (PEG-SPIOs) with the synthetic pseudotannin polygallol via interpolymer complexation (IPC). Changes in particle size and zeta potential were indirectly assessed via differences between PEG-SPIOs and IPC-SPIOs in particle velocity and scattering intensity using near-field light scattering. The local scattering intensity is correlated with the distance between the particle and waveguide, which is affected by the size of the particle (coating thickness) as well as the interactions between the particle and waveguide (related to the zeta potential of the coating). Therefore, we report here the use of near-field light scattering using nanophotonic force microscopy (using a NanoTweezerTM instrument, Halo Labs) to determine the changes that occurred in hydrated particle characteristics, which is accompanied by an analytical model. Furthermore, we found that altering the salt concentration of the suspension solution affected the velocity of particles due to the change of dielectric constant and viscosity of the solution. These findings suggest that this technique is suitable for studying particle surface changes and perhaps can be used to dynamically study reaction kinetics at the particle surface.

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Influence of Lignosulfonates on the Stability of Dimethomorph Water Based Suspension

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.550-553.51 ◽

2012 ◽

Vol 550-553 ◽

pp. 51-56

Author(s):

Yu Xia Pang ◽

Ting Zhou ◽

Hong Ming Lou ◽

Ming Song Zhou

Keyword(s):

Molecular Weight ◽

Zeta Potential ◽

Steric Effect ◽

Particle Surface ◽

Electrostatic Repulsion ◽

Particle Sizes ◽

Sodium Lignosulfonate ◽

Dispersive Effect ◽

Water Based ◽

The Stability

The dispersive effect of four lignosulfonates (Kinsperse126, sodium lignosulfonate, magnesium lignosulfonate and a modified lignosulfonate GCL4-1) on the stability of Dimethomorph (DMM) water based suspension with different particle sizes was investigated. DMM suspension without dispersant was unstable owing to the strong aggregation of particles, while the stability was increased after the addition of lignosulfonate (LS), which can be adsorbed on the particle surface and weaken the aggregation of particles. Moreover, the higher sulfonated degree of LS, the better the dispersible ability was. Compared with LS of high sulfonated degree which could improve the zeta potential of DMM, LS with high molecular weight had larger adsorption capacity and steric effect on the pesticide particles. Associated with the dispersive behavior of DMM suspension, the electrostatic repulsion was found to be the more important factor impacting the stability of DMM suspension by comparison with the steric effect.

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Effect of various types of interaction on the stability of some ternary interpolymer complexes involving poly(ethylene imine), poly(acrylic acid) and poly(ethylene glycol)

Polymer International ◽

10.1002/pi.2941 ◽

2010 ◽

Vol 60 (2) ◽

pp. 279-283 ◽

Cited By ~ 3

Author(s):

Bahman Vasheghani F ◽

Farzaneh Hosseinpour Rajabi ◽

Mohammad Hossein Ahmadi ◽

Nasaer Zenooz

Keyword(s):

Acrylic Acid ◽

Ethylene Glycol ◽

Poly Ethylene Glycol ◽

Ethylene Imine ◽

Interpolymer Complexes ◽

Poly Ethylene ◽

The Stability ◽

Poly Acrylic Acid

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An Experimental Investigation on Thermal Conductivity and Viscosity of Graphene doped CNTs /TiO2 Nanofluid

International Journal of Automotive and Mechanical Engineering ◽

10.15282/ijame.17.3.2020.16.0620 ◽

2020 ◽

Vol 17 (3) ◽

Author(s):

A.M. Zetty Akhtar ◽

M.M. Rahman ◽

K. Kadirgama ◽

M.A. Maleque

Keyword(s):

Thermal Conductivity ◽

Zeta Potential ◽

Base Fluid ◽

Minimum Quantity Lubrication ◽

Cutting Fluid ◽

Cutting Zone ◽

Observation Method ◽

The Stability ◽

The Relationship ◽

Zeta Potential Analysis

This paper presents the findings of the stability, thermal conductivity and viscosity of CNTs (doped with 10 wt% graphene)- TiO2 hybrid nanofluids under various concentrations. While the usage of cutting fluid in machining operation is necessary for removing the heat generated at the cutting zone, the excessive use of it could lead to environmental and health issue to the operators. Therefore, the minimum quantity lubrication (MQL) to replace the conventional flooding was introduced. The MQL method minimises the usage of cutting fluid as a step to achieve a cleaner environment and sustainable machining. However, the low thermal conductivity of the base fluid in the MQL system caused the insufficient removal of heat generated in the cutting zone. Addition of nanoparticles to the base fluid was then introduced to enhance the performance of cutting fluids. The ethylene glycol used as the base fluid, titanium dioxide (TiO2) and carbon nanotubes (CNTs) nanoparticle mixed to produce nanofluids with concentrations of 0.02 to 0.1 wt.% with an interval of 0.02 wt%. The mixing ratio of TiO2: CNTs was 90:10 and ratio of SDBS (surfactant): CNTs was 10:1. The stability of nanofluid checked using observation method and zeta potential analysis. The thermal conductivity and viscosity of suspension were measured at a temperature range between 30˚C to 70˚C (with increment of 10˚C) to determine the relationship between concentration and temperature on nanofluid’s thermal physical properties. Based on the results obtained, zeta potential value for nanofluid range from -50 to -70 mV indicates a good stability of the suspension. Thermal conductivity of nanofluid increases as an increase of temperature and enhancement ratio is within the range of 1.51 to 4.53 compared to the base fluid. Meanwhile, the viscosity of nanofluid shows decrements with an increase of the temperature remarks significant advantage in pumping power. The developed nanofluid in this study found to be stable with enhanced thermal conductivity and decrease in viscosity, which at once make it possible to be use as nanolubricant in machining operation.

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Host-Guest Interactions on Electrode Surfaces for Immobilization of Molecular Catalysts

10.26434/chemrxiv.12115026.v1 ◽

2020 ◽

Author(s):

Laurent Sévery ◽

Jacek Szczerbiński ◽

Mert Taskin ◽

Isik Tuncay ◽

Fernanda Brandalise Nunes ◽

...

Keyword(s):

Aqueous Media ◽

Heterogeneous Systems ◽

Catalytic Systems ◽

New Approach ◽

Molecular Systems ◽

Electrode Surfaces ◽

Catalytic Surfaces ◽

Oxide Electrodes ◽

The Stability ◽

Molecular Catalysts

The strategy of anchoring molecular catalysts on electrode surfaces combines the high selectivity and activity of molecular systems with the practicality of heterogeneous systems. The stability of molecular catalysts is, however, far less than that of traditional heterogeneous electrocatalysts, and therefore a method to easily replace anchored molecular catalysts that have degraded could make such electrosynthetic systems more attractive. Here, we apply a non-covalent “click” chemistry approach to reversibly bind molecular electrocatalysts to electrode surfaces via host-guest complexation with surface-anchored cyclodextrins. The host-guest interaction is remarkably strong and allows the flow of electrons between the electrode and the guest catalyst. Electrosynthesis in both organic and aqueous media was demonstrated on metal oxide electrodes, with stability on the order of hours. The catalytic surfaces can be recycled by controlled release of the guest from the host cavities and readsorption of fresh guest. This strategy represents a new approach to practical molecular-based catalytic systems.

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The Effect of pH and Storage Temperature on the Stability of Emulsions Stabilized by Rapeseed Proteins

Foods ◽

10.3390/foods10071657 ◽

2021 ◽

Vol 10 (7) ◽

pp. 1657

Author(s):

Karolina Östbring ◽

María Matos ◽

Ali Marefati ◽

Cecilia Ahlström ◽

Gemma Gutiérrez

Keyword(s):

Zeta Potential ◽

Storage Temperature ◽

Emulsion Stability ◽

Press Cake ◽

Strong Impact ◽

Soy Lecithin ◽

Rapeseed Protein ◽

Rapeseed Proteins ◽

Precipitation Ph ◽

The Stability

Rapeseed press cake (RPC), the by-product of rapeseed oil production, contains proteins with emulsifying properties, which can be used in food applications. Proteins from industrially produced RPC were extracted at pH 10.5 and precipitated at pH 3 (RPP3) and 6.5 (RPP6.5). Emulsions were formulated at three different pHs (pH 3, 4.5, and 6) with soy lecithin as control, and were stored for six months at either 4 °C or 30 °C. Zeta potential and droplet size distribution were analyzed prior to incubation, and emulsion stability was assessed over time by a Turbiscan instrument. Soy lecithin had significantly larger zeta potential (−49 mV to 66 mV) than rapeseed protein (−19 mV to 20 mV). Rapeseed protein stabilized emulsions with smaller droplets at pH close to neutral, whereas soy lecithin was more efficient at lower pHs. Emulsions stabilized by rapeseed protein had higher stability during storage compared to emulsions prepared by soy lecithin. Precipitation pH during the protein extraction process had a strong impact on the emulsion stability. RPP3 stabilized emulsions with higher stability in pHs close to neutral, whereas the opposite was found for RPP6.5, which stabilized more stable emulsions in acidic conditions. Rapeseed proteins recovered from cold-pressed RPC could be a suitable natural emulsifier and precipitation pH can be used to monitor the stability in emulsions with different pHs.

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