scholarly journals Practical Limits for Two Fundamental Approaches to Designing Particle Size Distributions to Address a Specific Physical Property like Viscosity

Polymers ◽  
2021 ◽  
Vol 13 (18) ◽  
pp. 3047
Author(s):  
Richard D. Sudduth
Keyword(s):  
Particle Size ◽  
Physical Property ◽  
Design Approach ◽  
Particle Sizes ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Initial Particle ◽  
Initial Particle Size ◽  
Final Particle ◽  
Straight Line

It has previously been shown that optimum particle size distributions with a maximum packing fraction can be achieved from a straight line plot of the accumulated sum of particle volume fractions versus the square root of particle size. This study addresses practical limits for two dominant fundamental approaches to designing particle size distributions to address the effect on a specific physical property such as viscosity. The two fundamental approaches to obtain such a straight line would include: the first design approach would be generated utilizing the same initial particle size, Dmin, but by using different ultimate particle sizes, Dmax. The second design approach would be generated where each distribution starts with the same initial particle size, Dmin, and ends with the same ultimate particle size, Dmax. The first design approach is particularly useful to identify the possible slopes available based on the smallest and largest particle sizes available. The second design approach can be utilized to identify the preferred ratio between particles, Z, and the number of different particle sizes, n, to be utilized in the final particle blend. The extensive empirical experimental evaluations of particle size distributions generated by McGeary were then utilized to confirm the limits.

In situ quasi-elastic scattering characterization of particle size effects on the hydration of tricalcium silicate

2004 ◽  
Vol 19 (11) ◽  
pp. 3242-3254 ◽  
Author(s):  
A.J. Allen ◽  
J.C. McLaughlin ◽  
D.A. Neumann ◽  
R.A. Livingston
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Tricalcium Silicate ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Hydration Time ◽  
Initial Particle ◽  
Initial Particle Size

The effects of different particle size distributions on the real-time hydration of tricalcium silicate cement paste were studied in situ by quasi-elastic neutron scattering. The changing state of water in the cement system was followed as a function both of cement hydration time and of temperature for different initial particle size distributions. It was found that the length of the initial, dormant, induction period, together with the kinetics of hydration product nucleation and growth, depends on the hydration temperature but not on the particle size distribution. However, initial particle size does affect the total amount of cement hydrated, with finer particle size producing more hydrated cement. Furthermore, the diffusion-limited rate of hydration at later hydration time is largely determined by the initial tricalcium silicate particle size distribution.

Determination of Latex Particle Size Distributions by Fractional Creaming with Sodium Alginate

1961 ◽  
Vol 34 (2) ◽  
pp. 433-445 ◽  
Author(s):  
E. Schmidt ◽  
P. H. Biddison
Keyword(s):  
Particle Size ◽  
Electron Microscope ◽  
Sodium Alginate ◽  
Mass Distribution ◽  
Average Particle Size ◽  
Average Particle ◽  
Particle Sizes ◽  
Size Distributions ◽  
Particle Size Distributions

Abstract Knowledge of mass distribution of particle sizes in latex is very important to the latex technologist. Therefore, it is desirable to have available a simple method for the determination of mass distribution of particle sizes. This paper presents a method, based on fractional creaming of latex with sodium alginate, which can be used in any laboratory without special equipment. The method is particularly advantageous for analyzing latexes of very wide particle size distributions. When analyzed with an electron microscope, these latexes require counting a very large number of particles. McGavack found that partial creaming of normal hevea latex with ammonium alginate gives concentrates of larger average particle size than the original latex. He found that the average particle size in the cream approaches that of the original latex as the amount of creaming agent is increased. In a previous paper from this laboratory, Schmidt and Kelsey demonstrated that the phenomenon of fractionation according to particle size with increasing amounts of creaming agent is applicable in a wide variety of anionic latex systems and in colloidal silica. Their results indicated also the existence of a quantitative relationship, independent of the nature of the dispersed particles, between the concentration of creaming agent and size of creamed particles. Maron confirmed fractionation with respect to particle size as a consequence of partial creaming with alginate. He showed that the mass average particle sizes of fractions, determined optically, cumulate to that of the original latex. Although the previous paper by Schmidt and Kelsey implied the basic concept of a method of determining particle size distribution by fractional creaming, it was not exploited at that time. In order to adapt the fractional creaming phenomenon to a quantitative method for particle size determination, we required a more precise knowledge of the relation between creaming agent concentration and size of particles creamed. It was proposed to establish this relationship with the aid of the electron microscope. Various factors influencing the creaming of latex, such as polymer concentration, electrolyte, soap content, and variability of the creaming agent, had to be considered in standardizing the creaming procedure.

Particle Size Characterisation of Tin Oxide (SnO2) Precipitated by Various Techniques: Consistency of Data

2007 ◽  
Vol 561-565 ◽  
pp. 2155-2158
Author(s):  
H. Taib ◽  
Charles C. Sorrell
Keyword(s):  
Particle Size ◽  
Light Scattering ◽  
Tin Oxide ◽  
Spherical Shape ◽  
Particle Sizes ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Oxide Powders ◽  
Spherical Agglomerates ◽  
The Individual

The particle size distributions of tin oxide powders produced from the calcining of precipitated tin oxalate were determined by four methods, these being two static and two dynamic light scattering techniques. Although the individual particle sizes were ~ 75 nm, all of the powders were heavily agglomerated as plates. The non-spherical shape resulted in the following interpretational problems: • None of the measurements was in agreement with any others. • There were very significant disagreements between the two light scattering methods. • The particle size distributions were multimodal. • The main peaks in the distribution curves, which were used to calculate the averages and standard deviations, were not Gaussian. The main uncertainty with these data is associated with the non-spherical agglomerates, which result in the multimodal size distributions. These probably were caused by variable-sized but large platy agglomerates.

Novel Precipitation Route to Silica Grain

1992 ◽  
Vol 271 ◽  
Author(s):  
Barbara Simms ◽  
Tom Gallo
Keyword(s):  
Particle Size ◽  
Acetic Acid ◽  
Aqueous Ammonia ◽  
Sol Gel ◽  
Average Particle ◽  
Particle Sizes ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Small Particles ◽  
High Degree

ABSTRACTWe describe a novel precipitation route to silica grain that lies in the interface between sol-gel and Stöber-type silica. The use of acetic acid as a catalyst for TEOS hydrolysis provides access to a precipitation window in which partially hydrolyzed TEOS and TEOS monomer, when reacted with aqueous ammonia, combine to form pumice-like silica particles in up to 90% yield as SlO2. Precipitated particles exhibit narrow particle size distributions that may be controlled for average particle sizes from 50µ to 400 µ. SEM micrographs show that the particles are agglomerates of small particles, which is consistent with the high degree of observed macroporosity.

scholarly journals Tuning Aerosol Particle Size Distribution of Metered Dose Inhalers Using Cosolvents and Surfactants

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Imran Y. Saleem ◽  
Hugh D. C. Smyth
Keyword(s):  
Particle Size ◽  
Fine Particle ◽  
Laser Diffraction ◽  
Particle Sizes ◽  
Size Distributions ◽  
Metered Dose Inhalers ◽  
Particle Size Distributions ◽  
Metered Dose ◽  
Aerosol Particle Size ◽  
Median Particle

Objectives.The purpose of these studies was to understand the influence of cosolvent and surfactant contributions to particle size distributions emitted from solution metered dose inhalers (pMDIs) based on the propellant HFA 227.Methods.Two sets of formulations were prepared: (a) pMDIs-HFA 227 containing cosolvent (5–15% w/w ethanol) with constant surfactant (pluronic) concentration and (b) pMDIs-HFA 227 containing surfactant (0–5.45% w/w pluronic) with constant cosolvent concentration. Particle size distributions emitted from these pMDIs were analyzed using aerodynamic characterization (inertial impaction) and laser diffraction methods.Results. Both cosolvent and surfactant concentrations were positively correlated with median particle sizes; that is, drug particle size increased with increasing ethanol and pluronic concentrations. However, evaluation of particle size distributions showed that cosolvent caused reduction in the fine particle mode magnitude while the surfactant caused a shift in the mode position. These findings highlight the different mechanisms by which these components influence droplet formation and demonstrate the ability to utilize the different effects in formulations of pMDI-HFA 227 for independently modulating particle sizes in the respirable region.Conclusion. Potentially, the formulation design window generated using these excipients in combination could be used to match the particle size output of reformulated products to preexisting pMDI products.

Processing of Optimized Cements and Concretes Via Particle Packing

MRS Bulletin ◽  
1993 ◽  
Vol 18 (3) ◽  
pp. 45-49 ◽  
Author(s):  
D.M. Roy ◽  
B.E. Scheetz ◽  
M.R. Silsbee
Keyword(s):  
Particle Size ◽  
Discrete Systems ◽  
Particle Packing ◽  
Particle Sizes ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Small Particles ◽  
Fresh Material ◽  
Simple Cubic ◽  
Packing Efficiency

It has been well-recognized for many years that the particle-size distributions of the cement and the grading of the aggregates play an important role in determining the properties and characteristics of cement and concrete products. DSP (densified with small particles) type cements and concretes, to a certain extent, MDF (macro-defect-free) cements, and optimized concretes are recently recognized outstanding examples of the application of this principle. The preset characteristics of the cementitious slurry are also strongly influenced by these factors. Both the workability of the fresh material, and the microstructure development are controlled to a considerable extent by these geometric parameters.Two seminal works in the areas of continuous particle size distributions and particle packing are those of Andreason and Furnas, respectively. Furnas deals mainly with discrete systems and Andreason with continuous distributions. As early as 1907, the concept of idealized particle packing was being used to optimize cements and concretes. Figure 1a shows an idealized cross section of a simple cubic packing of monodispersed spheres. This system has a maximum packing density of 0.65%. In an ideally packed system of discrete size ranges, the size of the next smallest particles would be such that they just fit in the gaps between the largest size particles, and so on for subsequent particle sizes; this system is represented schematically in Figure 1b. Not only the sizes but also the relative numbers of particles are important; Figures 1c and 1d show systems where some fraction of the smaller and larger particle sizes, respectively, are missing. Figure 1e shows a system where the size of the second largest particles is too large to fit into the gaps between the largest particles, resulting in a lower packing efficiency. Thus, both the particle size and fractions are important when considering packing efficiency.

scholarly journals Improvement of Ti Processing through Colloidal Techniques

2012 ◽  
Vol 520 ◽  
pp. 335-340 ◽  
Author(s):  
R.G. Neves ◽  
J.A. Escribano ◽  
Begoña Ferrari ◽  
Elena Gordo ◽  
Antonio Javier Sanchez-Herencia
Keyword(s):  
Particle Size ◽  
Sintering Behavior ◽  
Particle Sizes ◽  
Size Distributions ◽  
Colloid Chemistry ◽  
Particle Size Distributions ◽  
Broad Distribution ◽  
Dry Process ◽  
Chemical Physic ◽  
Titanium Powders

The colloid-chemistry control of metallic powders in aqueous slurries is proposed as a way to prepare Ti powders with small particle size for a better pressing behavior through the spray dry process. The chemical-physic behavior of titanium powders with two different particle size distributions dispersed in water has been studied by measuring the zeta potential as a function of pH, and dispersant concentration. The employment of poly-acrylic dispersants allowed the fabrication of stable slurries with solid contents up to 50 vol% that have been sprayed under different conditions to form agglomerates ranging between 50 and 200 µm. Conditions were selected to achieve spherical agglomerates formed by a broad distribution of particle sizes that shown excellent flowability. Agglomerates were pressed in a uniaxial die to measure the compressibility, showing an improvement in pressing behavior with respect to powders with bigger particle size. The sintering behavior is also improved, as values of 96 % of the theoretical density were obtained for compacts sintered in vacuum at 1100 °C for 30 minutes.

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