Dispergierung und Fragmentierung pyrogener SiO<sub>2</sub>‐ und TiO<sub>2</sub>‐Nanopartikel

Wengeler, Robert; Teleki, Alexandra; Vetter, M.; Wengeler, L.; Pratsinis, Sotiris E.; Nirschl, Hermann

doi:10.1002/cite.200650034

Cited by 2 publications

(3 citation statements)

References 5 publications

(3 reference statements)

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“…An exception is S10 with higher values indicating a diffusion dominated agglomeration process [45]. d f does not change by high pressure dispersion, due to sinter neck bonding [46] opposed to soft agglomerate processing studies [47,48] …”

Section: Nanoscale Powdersmentioning

confidence: 99%

Turbulent hydrodynamic stress induced dispersion and fragmentation of nanoscale agglomerates

Wengeler

Nirschl

2007

Journal of Colloid and Interface Science

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High pressure dispersion nozzles of 2.5-10 mm length and 125 µm diameter have been characterized in terms of fluid dynamics and dispersion experiments at 100-1400 bar. Elongational stresses at the nozzle entry (5 × 10 5 Pa) and turbulent stresses up to 10 5 Pa at a Reynolds number of 25,000 in turbulent channel flow are identified crucial for desagglomeration and aggregate fragmentation. Maximum stresses are calculated on representative particle tracks and related to agglomerate breakage. Agglomerates in the experimental study are in the range of the Kolmogorov micro scale (100-400 nm) and therefore break due to turbulent energy dissipation in viscous flow. Bond strength distributions could be determined experimentally from particle size distributions and fluid dynamics simulations, with primary particle erosion determined as dispersion mechanism for diffusion flame silica particles. Nanoscale agglomerates show a power law scaling for breakage with scaling exponents diverging from theory of floc dispersion. This is attributed to their strong bonding by sinter necks.

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Section: Nanoscale Powdersmentioning

confidence: 99%

Turbulent hydrodynamic stress induced dispersion and fragmentation of nanoscale agglomerates

Wengeler

Nirschl

2007

Journal of Colloid and Interface Science

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“…First of all, the properties of the particle system itself, like aggregate strength, size, shape and porosity, influence the forces required for deagglomeration and dispersion [16,8,17,18]. In this study, these parameters were kept constant.…”

Section: Methodsmentioning

confidence: 99%

“…3 describing the deagglomeration characteristics and efficiency is a clear sign of the strong interparticle interactions in the nanoparticle aggregates. For Aerosil 200V, they are mainly caused by strong sinter bridges between the SiO 2 particles [17,18]. Therefore, it is of major importance to improve the exploitation of energy for increased deagglomeration efficiency.…”

Section: Influence Of High Pressure Nozzle Geometry On Nanoparticle Dmentioning

confidence: 99%

High Pressure for Dispersing and Deagglomerating Nanoparticles in Aqueous Solutions

Sauter¹,

Schuchmann²

2007

Chem Eng & Technol

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Dispersing particles in a solution is a key requirement for a great variety of industrial products and processes, including pigments in coating applications or fillers in polymers. To be highly functional in the finished product, nanoparticles are required to be finely and homogeneously dispersed. As nanoparticles are often highly aggregated due to van der Waals interactions and sintering bonds, high stresses must be exerted on the constituent particles. High pressure dispersion is a promising new technology for deagglomerating and reducing process time and energy. Taking account of the influence of different mechanisms causing aggregate disruption, homogenizing pressure and nozzle geometry are the key process parameters. Therefore, adapting the nozzle geometry can lead to a targeted improvement of dispersion efficiency.

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Dispergierung und Fragmentierung pyrogener SiO₂‐ und TiO₂‐Nanopartikel

Cited by 2 publications

References 5 publications

Turbulent hydrodynamic stress induced dispersion and fragmentation of nanoscale agglomerates

Turbulent hydrodynamic stress induced dispersion and fragmentation of nanoscale agglomerates

High Pressure for Dispersing and Deagglomerating Nanoparticles in Aqueous Solutions

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Dispergierung und Fragmentierung pyrogener SiO2‐ und TiO2‐Nanopartikel

Cited by 2 publications

References 5 publications

Turbulent hydrodynamic stress induced dispersion and fragmentation of nanoscale agglomerates

Turbulent hydrodynamic stress induced dispersion and fragmentation of nanoscale agglomerates

High Pressure for Dispersing and Deagglomerating Nanoparticles in Aqueous Solutions

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Product

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Dispergierung und Fragmentierung pyrogener SiO₂‐ und TiO₂‐Nanopartikel