The Electron Microscope in the Determination of Particle Size Characteristics

2009 ◽  
pp. 90-90-5 ◽  
Author(s):  
James Hillier
Keyword(s):  
Particle Size ◽  
Electron Microscope

Modern Role of the Electron Microscope in Rubber Research

1961 ◽  
Vol 34 (2) ◽  
pp. 697-704 ◽  
Author(s):  
W. A. Ladd ◽  
M. W. Ladd
Keyword(s):  
Particle Size ◽  
Electron Microscope ◽  
Chain Structure ◽  
Main Role ◽  
Size And Shape ◽  
Carbon Gel ◽  
Electron Microscopes ◽  
Particle Size And Shape

Abstract Until recently, the main role of the electron microscope in rubber research was the determination of particle size and shape of reinforcing pigments and fillers. The electron microscope proved its value in its first industrial problem in 1940 when it showed the particle size of Micronex to be 28 mµ. In 1942 it established the correlation between particle size of carbon and rubber properties. The next contribution was the establishment of reticulate chain structure, in 1945, using stereo-photomicrography. The electron microscope led the way to the carbon gel concept when carbons producing different road wear results were shown to have equal particle size and structure. Micrographs of carbon gel were published in 1951. Studies of rubber latexes, various pigments and fillers were also applications of the electron microscope in which the determination of particle size and shape was involved. Today, improvements in resolution, development of new techniques and accessory equipment have greatly expanded the application of the electron microscope. This paper is concerned mainly with describing these new developments ; first, as a help to electron microscopists in the rubber field; second, to illustrate what can be done with the electron microscope, so that research and production men can recognize possible applications of this discerning tool to the solution of their problems. Electron microscopes have come a long way in the short 20-year period. Figure 1 shows the microscope used in our laboratories. This instrument is currently resolving detail as fine as 10 A or 1 mµ in routine daily operation. Its design makes possible the development of special holders and thereby increases its value as a research tool. Another piece of equipment that is as important in microscope research as the electron microscope itself is the evaporating unit shown in Figure 2. This is used for shadowing and forming replication films under vacuum, thus making possible studies of rubber surfaces and surfaces of pigments and other rubber ingredients. In shadowing, detail is made visible by coating the specimen with metal evaporated at an angle from the tungsten basket at A. Carbon can be evaporated by the arc at B, forming a replicating film or mold of the specimen. This will be discussed under “preparation”. Today, the proper preparation of specimens is the most important step in successful microscopy. The various preparations used are as follows.

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.

scholarly journals Perbandingan Teknik Aerasi dan Ultrasonikasi Gelasi Ionik Nanopartikel Deksametason Natrium Fosfat

2020 ◽  
pp. 102-109
Author(s):  
Bambang Hernawan Nugroho ◽  
Multi Tri Wardhani ◽  
Suparmi Suparmi
Keyword(s):  
Particle Size ◽  
Electron Microscope ◽  
Sodium Phosphate ◽  
Encapsulation Efficiency ◽  
High Energy ◽  
Mechanical Effect ◽  
Low Energy ◽  
Dexamethasone Sodium Phosphate ◽  
Fixed Concentration

Alginate, a biocompatible and biodegradable natural polymer, has been widely used as a drug molecular carrier using ionic gelation methods (crosslinking). One of the factors that must be taken into account in its preparation is the mechanical effect. The purpose of this study was to explain the preparation process and the characteristics of the calcium alginate crosslinkers as dexamethasone sodium phosphate carriers with low energy and high energy techniques. Nanosuspension is made in six formulas using 3 techniques: low energy (aeration), high energy (ultrasonication), low and high energy (aeration and ultrasonication) with a fixed concentration of dexamethasone sodium phosphate and sodium alginate, that is 0,2% and 0,1%, with 0,02% and 0,2% of calcium chloride. Determination of particle size, zeta potential, and morphology of nanoparticles using Particle Size Analyzer (PSA) and Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM). Determination of encapsulation efficiency using UV/Vis spectrophotometer and statistical analysis using MANOVA test. Synthesis of nanosuspension using a combination of low and high energy (aeration and ultrasonication) results in the most optimal characteristics with particle size value of 352.90 ± 6.10 nm, homogenized polydispersity index (0,52 ± 0,04), optimal potential zeta -44,40 ± 0,4 mV, the encapsulation efficiency of 49,5 - 74,8% and spherical particle shape. It can be concluded that the preparation using a combination of low and high energy is the most optimal preparation result.

scholarly journals Determination of Particle Size Distribution of Used Black Tea Leaves by Scanning Electron Microscope

2013 ◽  
Vol 61 (1) ◽  
pp. 111-115 ◽  
Author(s):  
Mohammad Abul Hossain ◽  
Shigeru Mori
Keyword(s):  
Particle Size ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Black Tea ◽  
Tea Leaves ◽  
Sem Images ◽  
Scanning Electron

The particle size distribution (PSD) of a particulate material is important in understanding its physical and chemical properties. Determination of PSD is essential in many physicochemical processes and production quality depends on the measurement and control of PSD. Scanning electron microscope (SEM), in addition to sieve analysis, has been used to determine the PSD of biomass materials like used black tea leaves (UBTL). Spherical, ellipsoidal and non-spherical particles of used black tea leaves were observed in SEM images. The PSD of four different sizes ranges of spherical and non spherical UBTL particles was determined from the measurement of SEM images of length wise and width wise diameters. The results enabled to determine the mean diameter or representative diameters of particles of wide size ranges. Dhaka Univ. J. Sci. 61(1): 111-115, 2013 (January) DOI: http://dx.doi.org/10.3329/dujs.v61i1.15106

The Analysis of Dislocations Using a Symmetry Criterion

1972 ◽  
Vol 30 ◽  
pp. 660-661
Author(s):  
J. C. Ingram ◽  
P. R. Strutt ◽  
Wen-Shian Tzeng
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Displacement Field ◽  
Standard Technique ◽  
Residual Image ◽  
Symmetry Criterion

The invisibility criterion which is the standard technique for determining the nature of dislocations seen in the electron microscope can at times lead to erroneous results or at best cause confusion in many cases since the dislocation can still show a residual image if the term is non-zero, or if the edge and screw displacements are anisotropically coupled, or if the dislocation has a mixed character. The symmetry criterion discussed below can be used in conjunction with and in some cases supersede the invisibility criterion for obtaining a valid determination of the nature of the dislocation.The symmetry criterion is based upon the well-known fact that a dislocation, because of the symmetric nature of its displacement field, can show a symmetric image when the dislocation is correctly oriented with respect to the electron beam.

Feasibility of Molecular Structure Determination With a High Resolution Electron Microscope

1968 ◽  
Vol 26 ◽  
pp. 338-339
Author(s):  
T. A. Welton
Keyword(s):  
Electron Microscope ◽  
Substrate Surface ◽  
Helical Axis ◽  
Base Plane ◽  
Resolution Electron ◽  
High Resolution Electron Microscope ◽  
High Degree ◽  
Degree Of Order ◽  
Purine Pyrimidine

An ultimate design goal for an improved electron microscope, aimed at biological applications, is the determination of the structure of complex bio-molecules. As a prototype of this class of problems, we propose to examine the possibility of reading DNA sequence by an imaginable instrument design. This problem ideally combines absolute importance and relative simplicity, in as much as the problem of enzyme structure seems to be a much more difficult one.The proposed technique involves the deposition on a thin graphite lamina of intact double helical DNA rods. If the structure can be maintained under vacuum conditions, we can then make use of the high degree of order to greatly reduce the work involved in discriminating between the four possible purine-pyrimidine arrangements in each base plane. The phosphorus atoms of the back bone form in projection (the helical axis being necessarily parallel to the substrate surface) two intertwined sinusoids. If these phosphorus atoms have been located up to a certain point on the molecule, we have available excellent information on the orientation of the base plane at that point, and can then locate in projection the key atoms for discrimination of the four alternatives.

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