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These technologies included a 52% solids solution of modified urea, and a 15% solids amine salt of a polyamide wax. Use of 0.2% fumed silica in pre-dispersed form (1% dispersion) performed marginally better at room temperature and significantly better than the other technologies, at elevated temperature.
Fumed silica, which can be used as a gelling agent, is amorphous and nonporous, and is prepared by flame hydroly-sis of SiCl4. Although the surface of fumed silica is naturally …
The dispersion is colloidally stable, eliminating the need for grinding and dust handling. The silica dispersion is dispersant-free to minimize incompatibility issues in a formulation. The high purity from the silica production and dispersion process offers good chemical and temperature stability without yellowing.
Variation of colloidal and interfacial interactions leads to a microstructural diversity in fumed silica dispersions exhibiting absolutely different sol- or gel-like rheological responses. In this study, fumed …
stabilization itself. Basic research on fumed silica has been performed on aqueous systems. And then, the dispersion of fumed silica in organic solvents and polar polymers has also been investigated.18,19 The unique stability of silica sol is correlated with mono-tonic short-range repulsion.20-23 Although this repulsion has
The fumed silica is a mixture of amorphous and crystalline silica, as evidenced by the sharp diffraction peak shown in Fig. 2 (b). In the XRD patterns of composites, the disappearance of a sharp crystalline peak at 34° and 38° confirmed the minimal amount of crystalline silica [ 24 ].
The initial dispersion is rapid. If the dispersion is mixed too long, the result will be an irreversible decrease in viscosity. Solubility / Solution Stability:2 Dispersions formed with fumed silica are quite stable, remaining unchanged for weeks to months, over a range of temperatures. Usage: Fumed silica have been used commercially in a wide
The rheological properties of hydrophilic fumed silica dispersed in polyethylene glycol (PEG) were investigated. The dispersion was prepared by dispersing the fumed silica in PEG with various concentrations. The reversible sol–gel transition was observed over 5 wt % of silica concentration as a function of temperature.
The jump curve demonstrates the new dispersion WF 7620 and gives a significant increase and improvement in rheological efficiency, compared to an existing water-based dispersion of fumed silica based on a fumed …
Herein, rheological behaviors of hydrophilic fumed silica (A200) dispersed in unentangled polypropylene glycol (PPG) were investigated as a function of weight averaged molecular weight (Mw) of PPG and volume fraction ( φ) of A200. While all the as-prepared dispersions are found to be sol-like, those with higher Mw and φ undergo thermal ...
Hydrophilic fumed silica powders are well dispersed at ϕ < 0.01 in polar dispersing fluids or polar polymer melts, and their phase states change from sol to gel with increasing ϕ. Such changes ...
Application Summary. High surface energy silicas require adequate shear for optimal dispersion into liquid. Improper powder wet-out and insufficient mixing lead to decreased efficiency (i.e. higher loadings of silica needed to achieve the desired properties), presence of large agglomerates, settling, poor stability and batch-to-batch inconsistencies.
AERODISP® Fumed Silica Dispersions as an Anti-Slip Agent for Paper Bags This technical brochure looks at the use of AERODISP® W 7520N and W 7330 N for increasing the coefficient of friction when applied to …
In this study, fumed silicas with different surface areas (200–400 m {sup 2}/g) and surface characteristics (hydrophilic or hydrophobic) are dispersed into moisture-cured polyurethane.
AERODISP® Fumed Silica Dispersions as an Anti-Slip Agent for Paper Bags. This technical brochure looks at the use of AERODISP® W 7520N and W 7330 N for increasing the coefficient of friction when applied to paper substrates. Newsletter introducing AERODISP® WR 8520. This is a hydrophobic AEROSIL® grade which has been pre …
In this paper, dispersion is investigated for a series of nanocomposites produced from commercially modified fumed silica mixed with styrene butadiene rubber, polystyrene, and polydimethylsiloxane. Surface modification includes variation in surface hydroxyl content, silox- ane, and silane treatment.
Fumed Silica (also called colloidal silica) is a fluffy white powder with an extremely low density, marketed under trade names such as Aerosil ®* and Cab-o-sil ®*. With both hydrophobic and hydrophillic grades available, it is widely used as a rheology modifier, …
During the dispersion process, fumed silica aggregate particles are stably broken down to small sizes of 50-300 nm (as measured by light-scattering techniques) that are extremely difficult to destabilize. …
In the montmorillonite systems in particular, this results in the surprising consequence that equilibrium solvent uptake and mechanical properties are independent of dispersion state. We conclude that edge interactions play a more significant role than degree of exfoliation, a result unique in the field of polymer nanocomposites.
pH value in 4% dispersion : 3.9～4.5: 3.9～4.5: 3.7～4.5: ... Fumed silica, or pyrogenic silicon dioxide, is one kind of pure amorphous white inorganic powder that has a high specific surface area, nano-scale primary particle size, and a relatively high (among silica products) concentration of surface silanol groups. The properties of fumed ...
Application Summary. High surface energy silicas require adequate shear for optimal dispersion into liquid. Improper powder wet-out and insufficient mixing lead to decreased efficiency (i.e. higher loadings of silica needed …
Fumed Silica is a notoriously difficult powder to disperse due to its extremely low density. As the powder is so fine, it tends to float on top of liquid surfaces and so it can be very difficult to wet out and processing often takes a long time. This also causes issues due to dusting. A degree of shear is also required to complete dispersion ...
Fumed Silica is a notoriously difficult powder to disperse due to its extremely low density. As the powder is so fine, it tends to float on top of liquid …
AERODISP® Fumed Silica and Metal Oxide Dispersions Since 1953, dispersion chemistry at Evonik has been based on fumed silica. Today, we provide various dispersions for …
Historically, there are many tailor-made designs that resulted from fumed silica's adaptable character. These designs create performance attributes including rheological flow control, suspension, reinforcement, and scratch resistance using standard high-speed dispersion which replace more intense bead milling to achieve high efficiency.
Hydrophilic fumed silica (A200) of 12 nm in diameter of primary spherical particles (according to the provider) was provided by Evonik Degussa Co., Akron, OH, USA. The density of silanols on the surface of A200 was determined as 2.50 nm−2 by titration using lithium aluminium tetrahydride. 2.2. Sample preparation