Application method powders

The application methods will be categorised by the physical form of the thermoplastic, e.g. liquid, powder, granule. 

The weaknesses associated with the flow through an orifice and angle of repose measurements limit their application for powder flow studies and hopper designs. Consequently, several powder shear testers and methods that permit a more thorough and precisely defined assessment of powder flow characteristics were developed. Shear testers that measure the frictional characteristics of a powder bed under load yield valuable information with regard to powder flow in high-speed tablet equipment. A number of types of shear cell testers are available, but the most common types used in the pharmaceutical industry are the Jenike shear cell and the Schulze ring shear tester.61,62... 

The use of large-surface area activated charcoal or carbon (approximately 500-1500 m2/g), either as powder activated carbon (PAC) or granular activated carbon (GAC), is the most popular adsorption technique. It is a relatively simple, low-cost, and widely applicable method of pollutant removal, and the literature is replete with descriptions of applications. The GAC version is mostly used in effluents that have already received normal biological treatment... 

In contrast to the coating pans, small particles such as beads, pellets, granules, and powders are generally coated using the fluidized bed or air suspension method, which utilizes a carrier gas to keep the cores in motion. The high air current makes this technique more efficient at water removal. The bottom spray technique is one of the most common fluidized bed application methods and a schematic of this process is shown in Fig. 4A. A perforated distribution base plate allows sufficient air into the product container to force the particles up into a cylindrical or slightly conical coating chamber, known as a Wurster insert. These inserts have been recently improved to keep... 

This book is an advanced introductory text about modern methods and applications of powder diffraction in research. A strong working knowledge of diffraction and crystallography is assumed. This book does not present a basic introduction to crystallography and diffraction from crystals, which is available in many introductory texts and other books, such as the excellent Fundamentals of Powder Diffraction by Pecharsky and Zavalij (Kluwer Academic Publishers, Boston, 2003). This book presents a broad overview of current methods and applications, including their theory and practice, with useful information on getting started in these methods. The book is written by renowned experts in the respective techniques. 

It is believed that this method of comparing two different powders most likely has an important future in industrial processing. Particle shape is very sensitive to the conditions under which the particles are made. Slight variations, which may not be measurable with normal means in an industrial operation, will significantly alter particle shape. Consequently, this characteristic can become a powerful tool not only for understanding the process but also for its control. In the long run, an equally important application of powder signatures may be their use in specifications. 

The finite element (FE) method is a very versatile numerical method that may be used to solve almost any problem, provided that the solution may be considered as a continuously varying function of position and time (40,41). At first sight, it may appear that the FE method would therefore have limited applicability for powders, since quantities such as density, stress, and strain do not vary continuously on the particle scale. However, a sufficiently fine powder may be idealized as a hypothetical continuous material, formally obtained by averaging over representative volume elements (42,43). These volume elements must be much larger than the particle size and at the same time much smaller than macroscopic dimensions of interest (such as the tablet height or diameter), and hence, other methods are required for coarse powders or granular materials (see later in the text). 

The ultimate choice of the application method itself will further be determined by an analysis of many factors. Whether the material to be applied is solid, liquid, or powdered thick or thin clear, metallic, or wrinkled or waterborne or oil based are all... 

Electrostatic Powder Spraying. The success of the electrostatic liquid application methods in the finishing field and the proven viability of the fluidized bed powder technique combined to suggest... 

Most modem SSNMR experiments on the quadmpolar halogen nuclei are carried out on powdered samples. We present briefly here an overview of the most commonly applicable methods to be used on stationary and MAS powdered samples. 

The action of sulfur dioxide in the presence of copper powder or copper(i) oxide, which act as reducing agents, provides a useful and generally applicable method of replacing a diazonium by a sulfinic acid group.460... 

Solvent-free organoniagnesium compounds are usually obtained as amorphous or microcrystalline polymeric materials. For this reason. X-ray diffraction studies depend either on the application of powder diffraction techniques [43.44] or on special and/or fortuitous methods of crystallization [32,45j. The structures 6.1-6.4 thus determined all follow essentially the same pattern a polymeric chain formed from nuiiually perpendicular four-membered rings Mg R ct>nncctccl via spiro magnesium atoms as slunvn In Scheme 9.5. 

Compression-molding is one of most applicable methods of processing plastic masses [143]. The press material, in the form of a powder, granules or pellets, is charged into the mold and subjected to heat and pressure effects. The article is molded and cured in the heated state. The molding pressure... 

Lignocellulosic material can also be analyzed by IR spectrometry. This analytical method was used for characterization of modified lignin and cellulose in various ways <>. Quantification by infrared spectrometry has been reported, for example, in analysis of the three basic constituents in sweet gum and white oak chips pretreated at temperatures ranging from 140 to 280 C. > using the diffuse reflectance FTIR spectrometry (DRIFT). The technique is simple and applicable to powdered solids and dark samples and... 

The layer thickness is determined by the preheating temperature, the heat content of the parts, the dipping time, and the coating powder. Parts with complicated shapes or with different substrate thicknesses are difficult to coat. The layer thicknesses obtained by the various application methods and the resultant use profiles are summarized in Table 8.7. 

Single crystal ENDOR measurement is an informative but not always applicable method to identify paramagnetic species in solids. It is for instance difficult to obtain single crystals of biochemical materials. In other cases the paramagnetic species are intentionally trapped in a disordered matrix or in a frozen solution. The ENDOR lines are then usually broadened by the anisotropy of the magnetic couplings. Some data that a single crystal analysis can provide are difficult to extract from a powder sample. However, a considerable amount of information can often be obtained from ENDOR spectra of disordered systems. 

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