Particle sizing in highly turbid dispersions by Photon Density Wave spectroscopy: Bidisperse systems

Bressel, Lena; Wolter, Juliane; Reich, Oliver

doi:10.1016/j.jqsrt.2015.01.025

Cited by 13 publications

(4 citation statements)

References 11 publications

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“…PDW spectroscopy is a new inline PAT that determines the absorption coefficient µ a as well as the reduced scattering coefficient µ s ’ of the dispersion in real time without dilution or sampling. Here, physical and chemical characteristics of the analyzed sample can be calculated from the optical coefficients [ 24 , 25 , 26 , 27 , 28 , 29 ]. In a recent study [ 23 ] the evolution of the particle size during the synthesis of PVAc was monitored by PDW spectroscopy and increasing particle sizes were observed as expected.…”

Section: Introductionmentioning

confidence: 99%

Process Characterization of Polyvinyl Acetate Emulsions Applying Inline Photon Density Wave Spectroscopy at High Solid Contents

et al. 2021

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The high solids semicontinuous emulsion polymerization of polyvinyl acetate using poly (vinyl alcohol-co-vinyl acetate) as protective colloid is investigated by optical spectroscopy. The suitability of Photon Density Wave (PDW) spectroscopy as inline Process Analytical Technology (PAT) for emulsion polymerization processes at high solid contents (> 40% (w/w)) is studied and evaluated. Inline data on absorption and scattering in the dispersion is obtained in real-time. The radical polymerization of vinyl acetate to polyvinyl acetate using ascorbic acid and sodium persulfate as redox initiator system and poly (vinyl alcohol-co-vinyl acetate) as protective colloid is investigated. Starved–feed radical emulsion polymerization yielded particle sizes in the nanometer size regime. PDW spectroscopy is used to monitor the progress of polymerization by studying the absorption and scattering properties during the synthesis of dispersions with increasing monomer amount and correspondingly decreasing feed rate of protective colloid. Results are compared to particle sizes determined with offline dynamic light scattering (DLS) and static light scattering (SLS) during the synthesis.

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Section: Introductionmentioning

confidence: 99%

Process Characterization of Polyvinyl Acetate Emulsions Applying Inline Photon Density Wave Spectroscopy at High Solid Contents

et al. 2021

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“…It is possible to use another number of wavelengths and detector bers to perform the measurements, however, this would have an impact on the precision. [8][9][10][11][13][14][15][16][17] It is a very efficient method, which is particularly well suited for dispersions with low absorption, and high scattering. Given that polymer dispersions full these requirements, we examined PDW spectroscopy regarding its potential for high solid content emulsion polymerization.…”

Section: Introductionmentioning

confidence: 99%

In-line monitoring of latex-particle size during emulsion polymerizations with a high polymer content of more than 60%

Jacob

Pauer

2020

RSC Adv.

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“…Also shown are the values for a binary hard-sphere distribution, calculated by the theoretical formula of Ashcroft & Langreth (1967). The theoretical formula is not shown here due to its complex form, and the readers can refer to the original paper of Ashcroft & Langreth (1967) and the paper of Bressel, Wolter & Reich (2015) for more information. As shown in figure 9, the simulated values of are in good agreement with the theoretical values, which means that the distribution of the relative position between small and large particles on the horizontal plane is homogeneous.…”

Section: Figurementioning

confidence: 99%

Particle–particle drag force in inertial bidisperse gas–particle suspensions

Duan

Chen

et al. 2022

J. Fluid Mech.

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Particle-resolved direct numerical simulations are employed to investigate the particle–particle drag force in the bidisperse gas–particle suspensions where the particles are smooth and the single-particle velocity distribution function is Maxwellian. The particle Reynolds number ranges from 6.7 to 123.8, and in this range the particle inertia is high enough that the lubrication force is not essential. It is found that the relation derived by the kinetic theory of granular flow (KTGF) highly overestimates the particle–particle drag force. This is because the pre-collision velocities of colliding particles are not completely uncorrelated with each other. From the time sequence of collision events, it is observed that the particle pair that has just collided will probably collide again after a short time due to the restriction of the particle motion in dense suspensions. Since the post-collision velocities of the first collision cannot relax entirely in such a short time, the relative velocity before the subsequent collision is statistically smaller than the domain-averaged relative velocity. Consequently, the particle–particle drag force is over-predicted when the domain-averaged relative velocity is used. For this reason, this work assumes that the particle–particle drag force is determined by the relative velocity within a local region near large particles. When the local region is set to be the spherical shells centred on the centres of large particles and with an outer radius of a mean free path of small particles, the KTGF-based relation can reasonably predict the particle–particle drag force.

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Particle sizing in highly turbid dispersions by Photon Density Wave spectroscopy: Bidisperse systems

Cited by 13 publications

References 11 publications

Process Characterization of Polyvinyl Acetate Emulsions Applying Inline Photon Density Wave Spectroscopy at High Solid Contents

Process Characterization of Polyvinyl Acetate Emulsions Applying Inline Photon Density Wave Spectroscopy at High Solid Contents

In-line monitoring of latex-particle size during emulsion polymerizations with a high polymer content of more than 60%

Particle–particle drag force in inertial bidisperse gas–particle suspensions

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