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Morphological characterization microscopic methods

In a general way, the identification of asbestos fibers can be performed through morphological examination, together with specific analytical methods to obtain the mineral composition and/or stmcture. Morphological characterization in itself usually does not constitute a reHable identification criteria (1). Hence, microscopic examination methods and other analytical approaches are usually combined. [Pg.351]

Microscopic methods. While microscopic methods provide direct visual information on membrane morphology as discussed earlier, determination of pore size, especially meaningful pore size distribution, by this type of methods is tedious and difficult. Advances have been made on the electron microscopy techniques to visualize membrane surface pores. For example, Merin and Cheryan [1980] have developed a replica-TEM technique to observe membrane surface pores. Nevertheless, microscopic methods have remained primarily as a surface morphology characterization tool and not as a pore size determination scheme. [Pg.102]

Morphological characterization can be conducted by light and electron microscope techniques and by X-ray diffraction and thermal analysis, often used to determine crystallinity. Standard mechanical tests can be used to determine strength, extension to break in tension, and toughness. Normally, a selection of characterization methods is used with samples exposed for selected periods. When mechanical tests are used, the exposure period increment must be fairly short, in case a recovery phenomenon is present (see the section Engineering Properties—Consequences of Photodegradation ). Other tests related to appearance. [Pg.2109]

Because of the expected small dimensions of the oxidation products and of the oxide scale after short oxidation times it was necessary to use electron microscopic methods to characterize the samples after oxidation. Besides scanning electron microscopy (SEM) transmission electron microscopy (TEM) was mainly used to describe the morphology of the oxide scale and to identify the oxidation products by energy dispersive X-ray analysis (EDX) as well as electron diffraction. A detailed description of the preparation of TEM cross-sections and of the experimental procedure is given in [12]. [Pg.246]

Microscopy remains the benchmark technique against which most others are compared, especially for particle sizing. It is particularly useful for identifying interparticle interactions and associations, specifically for floe or aggregate characterization and determination of floe morphology, which are difficult using other techniques. Therefore, microscopic methods are discussed in more detail than other methods. [Pg.53]

Microscopic Methods - Morphology Study and Sizing (0.001-200 pm) Microscopic analyses are and have always been indispensable tools in particle studies. For example, in 1827 the English botanist Robert Brown discovered the random thermal motion of flower pollen particles in suspension now known as Brownian motion" using an optical microscope. A simple optical microscope can provide visual observation and inspection of individual particles features and dimensions down to the micron range. Microscopes are also widely used in preparation of samples for other particle characterization techniques to check whether particles have been properly dispersed. [Pg.14]

Microscopic instruments such as scanning electron microscopy (SEM) and field emission SEM (EESEM) are useful for direct observation on the morphology of membrane surface and cross section (Table 15.3i). Use of microscopic methods for characterizing membrane pores provides information on pore geometry, which is difficult to obtain by other characterization techniques. Resolution of SEM and EESEM can be down to 1 nm [178], Therefore, the size, shape, and distribution of pores on ME and UF membranes can be visualized under SEM and FESEM. [Pg.557]


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