Mechanical particle size analysis

Table 13.1 covers general information for different particulates, liquids in gas, typical particles and gas dispersoids, behavior of particles in the human body, charging mechanisms, principles of particle size analysis, methods for particle size analysis, and an estimation of the general collection efficiency of available commercial particle removal equipment. 

D. Q. Craig, S. A. Barker, D. Banning, and S. W. Booth, Investigation into the mechanisms of self-emulsification using particle size analysis and low frequency dielectric spectroscopy, Int. J. Pharmaceut. 114 103-110 (1995). 

It must be stressed that, in the context of this book, the treatment of methods of particle size analysis, which are of great importance for all unit operations of mechanical process technology, must be simple and can not be complete. The task of these chapters will be to provide an overview, to discuss specific problems and limitations of certain methods, and to point out suitable procedures for application in size enlargement. For more detailed information the extensive literature covering this field should be consulted. 

Particle size analysis is useful for assessing attrition because both fragmentation and fine formation yield separate particle populations with different sizes. Production of midsize particles by means of shattering will lower the particle population s mean size and increase its size spread, as formation of fines through surface erosion will make the overall size distribution bimodal or multimodal. Barletta et al. (1993b) summarizes the different size distribution patterns in attrition resulting from the predominant attrition mechanisms and reviews the different models that fit these distributions. 

An important advantage of the ultrasonic method of particle size analysis over other methods is its applicability to systems that are concentrated, electrically non-conductive and optically opaque. Equations (V.46 - V.49) indicate that attenuations due to different mechanisms of acoustic losses are proportional to the volume fraction of the dispersed phase. This dependance becomes critical for the evaluation of particle size in concentrated dispersions. A number of studies (see [26,27], and references therein) have showed that such proportionality does not hold over the entire range of volume fractions, which indicates that eqs. (V.46) - (V.49) are not suitable for the characterization of concentrated disperse systems. 

Salama, A. I. A. Particle Size Analysis Mechanical Techniques, Encyclopedia on Analytical Science Academic London, 1995. 

Particle size determines more or less the origin, the chemical and optical properties, the mechanism of removal from the atmosphere and therefore it plays an important role in the sampling strategy planning. Generally particles with diameter less than 2.5 p-m are referred to as fine, and those with greater diameter are referred to as eoarse (aerosol particle size analysis is described in Griffits et al. (1998)). 

Soil Particle-Size Analysis. The hydrometer method was used to perform a mechanical analysis of the soils (11). 

The present work confirmed the layer by layer assembly of ZMP nanocontainers and the release mechanism of corrosion inhibitor. FTIR and TEM study confirms the successful formation of ZMP nanocontainer as a layer by layer system with the aid of ultrasonic irradiation. Zeta potential and particle size analysis also shows the formation of layers and shows appropriate change in the surface charge, which could be responsible for the release mechanism initiated by the change in pH. Release study and corrosion results from Tafel plot and corrosion rate analysis showed significant improvement in the anticorrosion properties of coatings due to the optimum loading of the ZMP nanocontainers. 

Additionally, other features of polymer characterisation are discussed such as the determination of molecular weight, polymer fractionation techniques, chemical and thermal stability, resin cure, oxidative stability, photopolymers, glass and other transitions, crystallinity, viscoelasticity, rheological properties, thermal properties, flammability testing, particle size analysis and the measurement of the mechanical, electrical and optical properties of polymers. 

Measles. Unbroken bubbles that have penetrated the groundcoat into the cover-coat of vitreous enamels. Mechanical Analysis. A term sometimes used as a synonym of particle-size ANALYSIS (q.v.). 

Usually, we assume particles to be spherical for particle size analysis because a sphere is the only shape that can be described by one number, its diameter d. The precise shape of particles relevant for chemical and mechanical engineering (coal, catalysts, ores, cement, paint pigments etc.) differs, but we can easily convert the volume (Vp) or the mass of a particle (mp) into the diameter of an equivalent sphere (equivalent sphere theory) ... 

The apparent lift experienced by micron size particles migrating close to a wall has not been satisfactorily explained. Our empirically derived lift force expression is consistent with the observation that calibration plots of log(retention time) versus log(diameter) are invariably quite linear over a wide range of particle sizes. Work is in progress to more fully elucidate the nature and mechanism of the lift forces. In the meantime, rapid and accurate particle size analysis, with the advantage of collectable size fractions, can presently be achieved based on empirical calibration and density compensation. 

As on previous occasions, the reader is reminded that no very extensive coverage of the literature is possible in a textbook such as this one and that the emphasis is primarily on principles and their illustration. Several monographs are available for more detailed information (see General References). Useful reviews are on future directions and anunonia synthesis [2], surface analysis [3], surface mechanisms [4], dynamics of surface reactions [5], single-crystal versus actual catalysts [6], oscillatory kinetics [7], fractals [8], surface electrochemistry [9], particle size effects [10], and supported metals [11, 12]. 

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