Uneven-shaped particles

PS/PHEM A particles in micron-size range were also obtained by applying the single-stage soapless emulsion copolymerization method [124]. But, this method provided copolymer particles with an anomalous shape with an uneven surface. PS or PHEMA particles prepared by emulsifier-free emulsion polymerization were also used as seed particles with the respective comonomer to achieve uniform PS/PHEMA or PHEMA/PS composite particles. PS/PHEMA and PHEMA/PS particles in the form of excellent spheres were successfully produced 1 iLitm in size in the same study. 

In the second stage, cross-link formation triggers phase separation, and further cross-link fixes the unevenly localized and deformed shape of particle. Thus, the red-cell-like particles are prepared during polymerization and not formed during isooctane evaporation. The red-cell-like particles find practically use for controlling rheological and optical characteristics in the coating and paint industry. 

The unevenness coefficient of particle surface decreased with larger shape index and had a critical value. Therefore, the particle shape modification process was considered in such a way that the submicro uneven particle surface was smoothed at first and, in consequence, the macro shape was processed to be spherical. 

Adsorption column preparation and loading. In order to obtain satisfactory results, the tube must be uniformly packed with the adsorbent uneven distribution may lead to the formation of cracks and channels and to considerable distortion of adsorption band shapes. If there is any doubt concerning the uniformity of particle size of the adsorbent powder it should be sifted before use to remove the larger particles fines are removed from the adsorbent using a sedimentation procedure immediately prior to column packing. In this the alumina or silica gel adsorbent is stirred into between five to ten times its volume of the selected solvent or solvent system, allowed to settle for five minutes and the supernatant liquor decanted off the procedure is repeated until the supernatant liquid is clear. 

It should be noted that the combustion tests were conducted with only primary air supply. Attempts were made to keep the feed rate and excess air as similar as possible between trial burns, however, the operation conditions were very hard to keep fixed, as the excess air was controlled manually and these biomass fuels do not have good flow characteristics due to their inconstant particle shape, uneven particle size distribution and high moisture content. Many studies related to incomplete combustion have focused on processes with two-stage air supply and have identified that excess air is a key factor influencing the formation of CO and CH (2, 4, 5. 13). It has also been shown that each wood furnace has a typical correlation between the CO-emissions and the excess air ratio regardless of fuel type (13). 

Liquids exhibit many characteristics that help us understand their nature. We have already mentioned their low compressibility, lack of rigidity, and high density compared with gases. Many of the properties of liquids give us direct information about the forces that exist among the particles. For example, when a liquid is poured onto a solid surface, it tends to bead as droplets, a phenomenon that depends on the intermolecular forces. Although molecules in the interior of the liquid are completely surrounded by other molecules, those at the liquid surface are subject to attractions only from the side and from below (Fig. 10.6). The effect of this uneven pull on the surface molecules tends to draw them into the body of the liquid and causes a droplet of liquid to assume the shape that has the minimum surface area—a sphere. 

Figure 8.18 Stages in sintering. An initial compact of slightly uneven particles (part a), is gradually transformed into a solid (parts b-d). Usually, this involves shrinkage, change of shape and the formation of pores...

Table 5.4 ows some particle size distributions for Turkish perlites measured by dry-deving out the particles smaller than 90 tm and udng a Fritsch photosedimentograph on the fine firaction. Densities and bulk densities are also given. The very uneven distributions illustrate the effect of the conplex shapes of perlite particles and indicate... 

Spectroscopic characterization is also important in the study of oxide minerals. Among the many methods (Sections 7.3 through 7.7), it is important to mention X-ray fluorescence (XRF, Section 7.3.3), which allows a rapid elemental analysis of mineral samples. Electron microscopy allows observation of clay fraction particles shape and, coupled to X-ray spectroscopy, also elemental analysis (Section 7.5). Infrared spectroscopy (Section 7.4.3) is also frequently employed here, difference spectra combined with selective extraction procedures (Hass and Fine 2010) can be used to identify and study minor components (Golden, Dixon, and Kanehiro 1993). Nuclear magnetic resonance (NMR, Section 7.4.4) is in some cases useful (with uneven spin nuclei), for example, to distinguish octahedral and tetrahedral A1 centers (Bertsch and Parker 1996). 

A fine-particle silicone additive has been developed by GE Silicones to improve the surface and surface Interaction characteristics of polymers, rubbers and similar materials. A key application for the additive (Tospearl) is an antiblocking agent for thin plastics film. Added to the resin during compounding, the fine particle spheres (0.5 12 pm) protrude from the surface of the blown film to form a uniformly uneven surface that prevents adhesion between film layers. The particle size is selected depending on film thickness. The spherical shape of the particles, combined with good inherent lubricity of silicone, also improves the slip characteristics of the film. 

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