Determination of Average Particle Size of Synthetic Latices by Turbidity Measurements

1959 ◽  
Vol 51 (2) ◽  
pp. 118-118 ◽  
Author(s):  
A. B. Loebel
Keyword(s):  
Particle Size ◽  
Average Particle Size ◽  
Average Particle

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.

Controlling the Particle Size of Quantum Dots Incorporated in Hybrid Materials

1998 ◽  
Vol 519 ◽  
Author(s):  
Francisco Del Monte ◽  
Yuhuan Xu ◽  
John D. Mackenzie ◽  
B. Claflin ◽  
G. Lucovsky
Keyword(s):  
Particle Size ◽  
Chemical Interaction ◽  
Quantum Confinement Effect ◽  
Sol Gel ◽  
Average Particle Size ◽  
Average Particle ◽  
Aggregation Processes ◽  
Trifunctional Silane ◽  
Gel Technique

AbstractSemiconductor PbS quantum dot-doped Ormocers were successfully prepared by the sol-gel technique. Ormocers preparation was based on the use of trifunctional silane precursors at the solution stage. Formation of PbS particles took place in the pores of the Ormocers through lead precursor reaction with H2S gas. It was observed that temperature was an important factor in the reaction leading to the first appearance of PbS particles. The dot size of PbS was controlled through chemical interaction with the non-hydrolyzed groups of the trifunctional silane precursors. These groups prevent uncontrolled nucleation and aggregation processes during the particle formation and growth. The control of particle size was studied at different conditions for nucleation and aggregation. Determination of the average particle size was done by XR-Diffraction. Optical absorption spectra were also measured at the UV-VIS wavelength range. Absorption edge blue shifts show the quantum confinement effect in these materials.

scholarly journals Behavior of Particle Size Distributions, Means and BET Values in Ideal and Non-Ideal Morphology Systems in a TEM

2004 ◽  
Vol 12 (1) ◽  
pp. 30-33
Author(s):  
Paul Beauregard
Keyword(s):  
Particle Size ◽  
Surface Area ◽  
Average Particle Size ◽  
Atomic Layer ◽  
Average Particle ◽  
Tem Analysis ◽  
Transmission Electron ◽  
New Instrument ◽  
The Cost

Historically, one of the first jobs performed by the new instrument called a “transmission electron microscope” (TEM) was the determination of particle size and distribution. Particle size is still important in controlling the properties of sub-micron and nanoparticle products. The width and average particle size can determine the light scattering properties of a pigment like TiO2, for example. The cost of installing a TEM facility and TEM sample preparation issues makes TEM analysis expensive and labor intensive. So decades ago, nitrogen BET (Brunauer, Emmett, and Teller) surface area determinations were used on sub-micron powders and pigments to minimize these costs. The BET measurement of the exposed external surface area of a material is made by detecting and measuring the amount of nitrogen given off after absorption, assuming one atomic layer of nitrogen is adsorbed.

A New Method for Direct Determination of the Recoilless Fraction with Application to Magnetic Nanoparticles

2002 ◽  
Vol 721 ◽  
Author(s):  
Monica Sorescu
Keyword(s):  
Room Temperature ◽  
Average Particle Size ◽  
Direct Determination ◽  
Average Particle ◽  
Lattice Method ◽  
Recoilless Fraction ◽  
Single Room ◽  
Magnetite Particles ◽  
Physical Mixtures

AbstractWe propose a two-lattice method for direct determination of the recoilless fraction using a single room-temperature transmission Mössbauer measurement. The method is first demonstrated for the case of iron and metallic glass two-foil system and is next generalized for the case of physical mixtures of two powders. We further apply this method to determine the recoilless fraction of hematite and magnetite particles. Finally, we provide direct measurement of the recoilless fraction in nanohematite and nanomagnetite with an average particle size of 19 nm.

Determination of grinding parameters of fenugreek seed

1970 ◽  
Vol 26 (1) ◽  
pp. 16 ◽  
Author(s):  
S Balasubramanian ◽  
Rajkumar Rajkumar ◽  
K K Singh
Keyword(s):  
Particle Size ◽  
Energy Consumption ◽  
Moisture Content ◽  
Specific Energy ◽  
Feed Rate ◽  
Average Particle Size ◽  
Specific Energy Consumption ◽  
Average Particle ◽  
Fenugreek Seeds ◽  
Fenugreek Seed

Experiment to identify ambient grinding conditions and energy consumed was conducted for fenugreek. Fenugreek seeds at three moisture content (5.1%, 11.5% and 17.3%, d.b.) were ground using a micro pulverizer hammer mill with different grinding screen openings (0.5, 1.0 and 1.5 mm) and feed rate (8, 16 and 24 kg h-1) at 3000 rpm. Physical properties of fenugreek seeds were also determined. Specific energy consumptions were found to decrease from 204.67 to 23.09 kJ kg-1 for increasing levels of feed rate and grinder screen openings. On the other hand specific energy consumption increased with increasing moisture content. The highest specific energy consumption was recorded for 17.3% moisture content and 8 kg h-1 feed rate with 0.5 mm screen opening. Average particle size decreased from 1.06 to 0.39 mm with increase of moisture content and grinder screen opening. It has been observed that the average particle size was minimum at 0.5 mm screen opening and 8 kg h-1 feed rate at lower moisture content. Bond’s work index and Kick’s constant were found to increase from 8.97 to 950.92 kWh kg-1 and 0.932 to 78.851 kWh kg-1 with the increase of moisture content, feed rate and grinder screen opening, respectively. Size reduction ratio and grinding effectiveness of fenugreek seed were found to decrease from 4.11 to 1.61 and 0.0118 to 0.0018 with the increase of moisture content, feed rate and grinder screen opening, respectively. The loose and compact bulk densities varied from 219.2 to 719.4 kg m-3 and 137.3 to 736.2 kg m-3, respectively.  

Formulating SLN and NLC as Innovative Drug Delivery Systems for Non-Invasive Routes of Drug Administration

2020 ◽  
Vol 27 (22) ◽  
pp. 3623-3656 ◽  
Author(s):  
Bruno Fonseca-Santos ◽  
Patrícia Bento Silva ◽  
Roberta Balansin Rigon ◽  
Mariana Rillo Sato ◽  
Marlus Chorilli
Keyword(s):  
Drug Delivery ◽  
Particle Size ◽  
Drug Release ◽  
Drug Loading ◽  
Average Particle Size ◽  
Delivery Systems ◽  
Average Particle ◽  
Minor Importance ◽  
Routes Of Administration ◽  
Non Invasive

Colloidal carriers diverge depending on their composition, ability to incorporate drugs and applicability, but the common feature is the small average particle size. Among the carriers with the potential nanostructured drug delivery application there are SLN and NLC. These nanostructured systems consist of complex lipids and highly purified mixtures of glycerides having varying particle size. Also, these systems have shown physical stability, protection capacity of unstable drugs, release control ability, excellent tolerability, possibility of vectorization, and no reported production problems related to large-scale. Several production procedures can be applied to achieve high association efficiency between the bioactive and the carrier, depending on the physicochemical properties of both, as well as on the production procedure applied. The whole set of unique advantages such as enhanced drug loading capacity, prevention of drug expulsion, leads to more flexibility for modulation of drug release and makes Lipid-based nanocarriers (LNCs) versatile delivery system for various routes of administration. The route of administration has a significant impact on the therapeutic outcome of a drug. Thus, the non-invasive routes, which were of minor importance as parts of drug delivery in the past, have assumed added importance drugs, proteins, peptides and biopharmaceuticals drug delivery and these include nasal, buccal, vaginal and transdermal routes. The objective of this paper is to present the state of the art concerning the application of the lipid nanocarriers designated for non-invasive routes of administration. In this manner, this review presents an innovative technological platform to develop nanostructured delivery systems with great versatility of application in non-invasive routes of administration and targeting drug release.

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