Dispersions fabric coating

Special dispersion for coating polyester yarns to be used for technical fabrics (paper, felt, etc.) adhesive for pigment printing. 

Interfacial phenomena at metal oxide/water interfaces are fundamental to various phenomena in ceramic suspensions, such as dispersion, coagulation, coating, and viscous flow. The behavior of suspensions depends in large part on the electrical forces acting between particles, which in turn are affected directly by surface electrochemical reactions. Therefore, this chapter first reviews fundamental concepts and knowledge pertaining to electrochemical processes at metal oxide powder (ceramic powder)/aqueous solution interfaces. Colloidal stability and powder dispersion and packing are then discussed in terms of surface electrochemical properties and the particle-particle interaction in a ceramic suspension. Finally, several recent examples of colloid interfacial methods applied to the fabrication of advanced ceramic composites are introduced. 

An important application for aqueous dispersions of PTFE is the architectural fabric market. This product consists of fiberglass fabric coated with special forms of the aqueous dispersion. The resulting material is used as roofs in a wide variety of buildings, especially where a large area must be covered with minimum support. Notable examples of such use are the Pontiac Silver Dome, the airport terminal in Jeddah, Saudi Arabia (where 105 acres are enclosed), and many college and university stadiums or union buildings. 

Table A.6 shows that many other vinyl, allyl, isopropenyl, and other ester copolymers and their derivatives have potential uses as emulsifiers, dispersants, adhesives, coatings, photoreactive resins, aqueous thickeners, oil additives, and others. Allyl acetate-MA copolymer sodium salt is comparable to sodium tripolyphosphate as a detergent builder. In addition, the copolymer provides protection of the fabric against sodium perborate damage.

Wiersma et al. [284] described a method for preparation of P(Py) or P(ANi) + polyurethane dispersions which may be applied to textile fibers. Aqueous solutions of pyrrole (or anilinium sulfate) and Fe(N03)3 are added to a dispersion of polyurethane in water. After 20 hrs reaction time, a P(Py) (or P(ANi)) poly-(urethane) dispersion is obtained, which can then be used to fabricate coatings with claimed conductivities up to 10 S/cm. 

Dispersion Processing. A commercial aqueous dispersion of Teflon PEA 335 contains more than 50 wt % PEA particles, about 5 wt % surfactants and fillers. This dispersion is processed by the same technique as for PTEE dispersion. It is used for coating various surfaces, including metal, glass, and glass fabrics. A thin layer of Teflon PEA coating can also serve as an adhesive layer for PTEE topcoat. 

Water Dispersions. Polysulftde products are offered as aqueous dispersions (Thiokol WD-6). These are useful for applyiag protective coatings to line fuel tanks, and for concrete, wood, and ia some cases fabrics, felt, leather (qv), and paper (qv). It has been found that a stable emulsion can be made that contains both LP and manganese oxide curing agent. The emulsion can be thinned and appHed as a spray coating. After it is appHed, water evaporates and the LP cures to form a soHd mbber (13). 

Electrodeposition This method of paint application is basically a dipping process. The paint is water-based and is either an emulsion or a stabilised dispersion. The solids of the paint are usually very low and the viscosity lower than that used in conventional dipping. The workpiece is made one electrode, usually the cathode, in a d.c. circuit and the anode can be either the tank itself or suitably sized electrodes sited to give optimum coating conditions. The current is applied for a few minutes and after withdrawal and draining the article is rinsed with de-ionised water to remove the thin layer of dipped paint. The deposited film is firmly adherent and contains a minimum of water and can be stoved without any flash-off period. This process is used for metal fabrications, notably car bodies. Complete coverage of inaccessible areas can be achieved and the corrosion resistance of the coating is excellent (Fig. 14.1). 

All AB, alloys are very brittle and are pulverized to fine particles in the hydrid-ing-dehydriding process (see Sec. 7.2.1). Thus electrodes must be designed to accommodate fine powders as the active material. There are several methods of electrode fabrication Sakai et al [35] pulverize the alloy by subjecting it to several hydrogen absorption-desorption cycles, before coating the resulting particles with Ni by chemical plating. The powder is mixed with a Teflon dispersion to obtain a paste which is finally roller-pressed to a sheet and then hot-pressed to an expanded nickel mesh. The fabrication of a simple paste electrode suitable for laboratory studies is reported by Petrov et al. [37],... 

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