Bulk solid particle size analysis

A number of methods have been proposed for particle shape analysis these include verbal description, various shape coefficients and shape factors, curvature signatures, moment invariants, solid shape descriptors, the octal chain code and mathematical functions like Fourier series expansion or fractal dimensions. As in particle size analysis, here one can also detect intense preoccupation with very detailed and accurate description of particle shape, and yet efforts to relate the shape-describing parameters to powder bulk behaviour are relatively scarce.10... 

There are instances where a qualitative test for comparative or quality control (QC) purposes may be desired and the quantitative test methods used for equipment design or analysis purposes described in the preceding sections are not essential for the flow concerns being assessed. These non-scalable, qualitative tests may be used to measure cenain attributes/characteristics of the bulk solid within a pre-defined range. These attributes may include chemical composition, particle size, color, moisture, and often, flow properties. 

Molecular dynamics (MD) is an invaluable tool to study structural and dynamical details of polymer processes at the atomic or molecular level and to link these observations to experimentally accessible macroscopic properties of polymeric materials. For example, in their pioneering studies of MD simulations of polymers, Rigby and Roe in 1987 introduced detailed atomistic modeling of polymers and developed a fundamental understanding of the relationship between macroscopic mechanical properties and molecular dynamic events [183-186]. Over the past 15 years, molecular dynamics have been applied to a number of different polymers to study behavior and mechanical properties [187-193], polymer crystallization [194-196], diffusion of a small-molecule penetrant in an amorphous polymer [197-199], viscoelastic properties [200], blend [201,202] and polymer surface analysis[203-210]. In this article, we discuss MD studies on polyethylene (PE) with up to 120,000 atoms, polyethylproplyene (PEP), atactic polypropylene (aPP) and polyisobutylene (PIB) with up to 12,000 backbone atoms. The purpose of our work has been to interpret the structure and properties of a fine polymer particle stage distinguished from the bulk solid phase by the size and surface to volume ratio. 

NIR analysis is directed to the determination of bulk properties and concentrations of the sample. In order to ensure precision of analysis, a sufficient number of particles must be present in the sample cell. Hirschfeld [37] discussed the relationship of measurement error as a function of sample area geometry and the average diameter of the particles. One effect of large particle size in a solid sampling diffuse reflectance cell is that the light penetration changes, distorting the spectrum. This is a known phenomenon in the visible-NIR [38,39],... 

Selection of an appropriate mixer begins with an understanding of process requirements (e.g., quantity of bulk solids to be mixed, desired degree of mixedness, the need for batch integrity, upstream/downstream process) and material properties (e.g., particle size distribution, cohesiveness, particle shape, abrasiveness). The final analysis must then combine these factors with the operating and purchase cost to arrive at an engineering decision. 

Microscopy. Characterization of particulate from suspensions using microscopic methods is an effective method for establishing the size distribution of the particles and also their composition. Using properly prepared samples, automated image analysis techniques can be used that significantly reduce data collection times. Although the size distribution and composition of the suspended particles are important, the real strength of microscopic methods is the ability to observe particles in suspension and to determine how they interact and associate. There is little difference in microscopic methods applied to solids in suspension or to oil droplets in suspension (emulsions). As a result, the bulk of this discussion is borrowed from a similar chapter on emulsion characterization found in reference 19. 

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