Thermal posttreatment

Therefore, the first requirement is that the dye itself be present in a stable crystal modification that does not change during application. If such a modification cannot be obtained by synthesis, attempts must be made to generate it by thermal posttreatment, for instance, by heating the dye in an aqueous suspension in the presence of nonionic detergents. 

The purely thermal posttreatment of dried silicas, which depending upon the temperature leads to more or less strong splitting off of water, is only of major importance for silica gels and is termed activation . 

Feed materials for briquettes include coals of different properties pretreated coals, low-temperature coke, high-temperature coke breeze, or mixtures of these. Various binders are used in manufacturing the briquettes. The binder may be obtained partly during the pretieatment of the coal or during the carbonization of the briquette. The thermal posttreatment of briquettes at different temperatures, with or without the influence of oxygen in the air, leads to briquettes that (depending on the feed material, the treatment method, and the treatment temperature) have properties more or less similar to those of coke. 

If anthracite or low-volatile coals are used as feed materials, the comminuted coal usually mixed with an additional binder such as pitch or sulfite liquor. The briquettes undergo carbonization in one of several steps. The thermal posttreatment depends on the type of briquettes being treated and the desired properties of the final product. Heating rate and residence time in the hot zone are the deciding factors however, the composition properties of the raw briquettes also influence the processing steps and the nature of the final product. 

As already explained in Subsect. 4.2.3, the glassy blank for the manufacturing of the 8 m mirror is cooled first to room temperature and then converted to glass ceramic through a further thermal posttreatment. 

The results prove that the surface energy properties of plasma polymer films can be modified by using an appropriate thermal posttreatment process which appeared to be particularly useful for the production of strongly adherent protective coatings for metals. 

Parameters connected to the eventual post-treatments include take-up speed (stretching), chemical or thermal posttreatments (additive leaching, thermal annealing), and drying techniques (hexane, glycerol, etc.). 

Thermal chlorinations were carried out at 125°C. and photochemical chlorina-tions at about 35°C. No posttreatment was employed other than removal of dissolved hydrogen chloride, followed by the removal of solvents, if present, by heating under vacuum. No difference in plasticizer properties was observed for chlorinated n-paraffins made by the two methods. 

In practice, clean (very clean ) cleaved or otherwise smoothed metal surfaces should be made to effect a firm mechanical contact using a strong force but one that is still insufficient to cause macroscopic deformation even at an elevated temperature. This will have to be been done, usually, in vacuum or at least in an inert atmosphere. The problems of hard to get to (inaccessible) joints and possibly objectionable thermal conditions and the resultant undesired microstructures such as Kirkendall voids, for instance, are minimized, if not eliminated all together. Thus, good-quality, distortion-free joints requiring no additional machining or other posttreatment can be achieved. 

Thermal desorption systems can be broken into three key components pretreatment, the TDU, and posttreatment (Fig. 1) as discussed below. Additionally, thermal desorption systems are often used in conjunction with other treatment technologies as part of a treatment train. At previous RCRA and Superfund sites, thermal desorption has been used in conjunction with bioremediation, dechlorination, incineration, soil vapor extraction, soil washing, and solidification/ stabilization. " In these cases, the combination of technologies was required to meet the site s cleanup goals. 

The presence of contaminants in predominantly clay soils poses a difficult and potentially costly remediation problem. The low hydraulic conductivity of these soils prohibits the use of traditional pump-and-treat remediation techniques. Other treatment methods involving excavation and employing various thermal treatments are costly, energy intensive, and could themselves create other adverse environmental impacts. Incomplete remediation of contaminated clay could lead to posttreatment seepage and recontamination of the remainder of the site. For these reasons, much research has been done to advance the field of electrokinetic (EK)... 

Temperature is important, because it allows producing mechanically strengthened PECs. Temperature is an external posttreatment parameter affecting material properties and polyelectrolyte multilayer formation. Enhancement of mechanical properties and encapsulation efficiency due to shrinking of layers in response to thermal treatment has been reported by Kohler et al." In the case of PECs, a significant reduction of the permeability for low-molecular-weight compounds accompanies heat treatment due to the interplay of electrostatic and hydrophobic forces. PECs can be compressed or expanded in response to temperature stimuli, which can be enabled for encapsulation and release of active moieties. 

Freshly coagulated Lyocell fibers show low crystalline orientation for the (110) plane however, as NMMO is extracted, the orientation of the dry fibers is improved. Extensive drying often causes fibrils to cluster into larger structural units (bundles). Fink et al. [37] estimated that the diameter of the bundles is around 25 nm. Definitely, Lyocell fibers have fibrillar morphology that is affected by posttreatment thermal processes. 

The dimensions and accessibility of pores of zeohtes and microporous solids are confined to the subnanometer scale (<1.5 run), which hmits their applications when processing bulky molecules. Mesoporous materials with pore sizes ranging from 2 to 50 nm overcome these limitations. In contrast with microporous zeolites, these materials lack atomic ordering (crystallinity) in their silica walls as these are usually amorphous. The attractive properties of ordered mesoporous materials include well-defined pore system high surface area and pore sizes narrow pore size distribution tunable up to 100 nm existence of micropores in the amorphous wall (for thicker wall materials) existence of various wall (framework) compositions obtained from direct synthesis, or posttreatment or modification high thermal and hydrothermal stabilities if properly prepared or treated and various controllable regular morphologies on different scales from nanometers to micrometers. 

Porous carbons (e.g., activated carbons) are an important family of porous solids that have a wide spectrum of applications becanse of their remarkable properties, such as high specific surface area, chemical inertness, abundant repertory of surface functional groups, good thermal stability, and low cost of manufacture. Their chemistry and physics have been reviewed [22-25]. The most common way to produce activated carbons is to carbonize a carbon-containing precursor, followed by activation or posttreatment [26]. Becanse of practical requirements of various applications, techniques for control over the pore size of activated carbons have been the subject of research for several decades [18] for example, high burn-off activation, catalyst-assisted activation, and carbonization of polymer blends with thermally unstable components. For recent progress in the use of hydroxide activation, see Chapter 1 by Linares-Solano and coworkers in this volume [27]. However, none of these synthesis approaches is suitable for very precise control over pore structure, particle size, and morphology [19]. 

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