Powder-modified fabrication

Fabrication and Properties of Redispersible Polymer Powder-Modified Systems... 

The fabrication technique of redispersible polymer powder-modified mortar and concrete is about the same as that for latex-modified mortar and concrete. The materials and mix prc rtions used in this nnodified mortar and concrete are the same as those used in the latex-modified systems except that the addition of the redispersible polymer powders is involved. At present, commercially available redispersible polymer powders as cement modifiers are classified in Fig. 5.2. Table 5.2 gives the properties of typical redispersible polymer powders. The rediqretsible polymer powders are usually free-flowing powders, and have ash contents of 5 to 15%, whidi primarily come from the anti-blockirig aids. When the polymer powders are placed in water under agitation, they redtsperse or re-emulsify easily, and provide the polymer latexes with polymer particle sizes of 1 to 10 pm. 

Aqueous Dispersions. The dispersion is made by the polymerization process used to produce fine powders of different average particle sizes (58). The most common dispersion has an average particle size of about 0.2 p.m, probably the optimum particle size for most appHcations. The raw dispersion is stabilized with a nonionic or anionic surfactant and concentrated to 60—65 wt % soHds by electrodecantation, evaporation, or thermal concentration (59). The concentrated dispersion can be modified further with chemical additives. The fabrication characteristics of these dispersions depend on polymerization conditions and additives. 

If the new niche for the perfume is its use in cosmetics, toiletries or household product, then the niche-product interaction becomes very important. Perfumes are used specifically for their odor whereas in these new niches several new factors must be considered. For example, the perfume oil used in creams must not cause discoloration the fragrance used in a powdered detergent must be alkali resistant a fabric softener is expected to leave clothes with a pleasant odor and even a household cleanser must have a pleasant and functional odor, although active chlorine places difficulty on the stability of the perfume oil. Of course, decisions can affect or modify the product (perfume) or the niche (e.g. creams). 

Thus this book presents current developments and concepts in the chemical techniques for production and characterization of state-of-the-art ceramic materials in a truly interdisciplinary fashion. The 27 chapters are divided into five parts reflecting topical groups. The first part discusses the starting materials—how to prepare and modify them in the nanoscale range. Powders are the most heavily used form of starting ceramic materials. The synthesis, characterization, and behavior of ceramic powders are presented in parts I and II. In the third part, processing of ceramic films via the sol-gel technique is discussed. Fabrication of... 

The same polymerization process makes aqueous dispersions of PTFE as fine powder. The dispersion is concentrated and stabilized using a variety of ionic and nonionic surfactants. Several concentration methods have been reported including electrodecantation, evaporation and thermal concentration. Chemical additives to match them with the fabrication process or part property requirements can modify the final PTFE dispersion. 

In this paper, novel Nd YAG powders were synthesized via a modified co-precipitation method with alcohol-water as the precipitation solvent. Nd YAG transparent ceramics were fabricated by vacuum sintering using as-prepared ultrafine powders with 0wt%, 0.3wt%, 0.5wt% and 0.7wt% TEOS as additive. The densification and the microstructure evolution of the ceramics were mainly studied. 

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