Aramids manufacture

Standard Test Methods for Tire Yarns, Cords, and Woven Fabrics. ASTM standard D885M-94 includes test methods for characterizing tire cord twist, break strength, elongation at break, modulus, tenacity, work-to-break, toughness, stiffness, growth, and dip pickup for industrial filament yams made from organic base fibers, cords twisted from such yams, and fabrics woven from these cords that are produced specifically for use in the manufacture of pneumatic tires. These test methods apply to nylon, polyester, rayon, and aramid yams, tire cords, and woven fabrics. 

Aramid Fibers. Aromatic polyamide fibers exhibiting a range of mechanical properties are available from several manufacturers, perhaps the best known being Du Pont s proprietary fiber Kevlar. These fibers possess many unique properties, such as high specific tensile strength and modulus (see Fig. 4). Aramid fibers have good chemical resistance to water, hydrocarbons, and solvents. They also show excellent flame retardant characteristics (see High PERFORMANCE fibers Polyamdes). 

In recent years there has been considerable interest in aromatic polyamide fibres, better known as aramid fibres. These are defined by the US Federal Trade Commission as a manufactured fibre in which the fibre-forming substance is a long chain synthetic polyamide in which at least 85% of the amide linkages are attached directly to two aromatic rings. ... 

In reinforcing materials double-dipped polyesters for improved tire durability, plasma-treated yams for improved bonding in tire, and increased usage of aramid fabric as belt and application of PEN are the areas where manufacturers are showing interest. Introduction of new styles of steel wire geometry for improved mbber to metal adhesion and new steel wire coating formulations for improved mbber to metal bonding are other focused areas of development. 

Scientists and engineers at the University of Exeter are investigating whether natural fibers tike hemp and sisal could be used to make sustainable and eco-friendly brake pads [39]. The technology of brake pads turned green with the replacement of asbestos by aramids (hke Kevlar of DuPont) in the 1980s. Kevlar is very expensive and eco-friendly alternatives like hemp, jute, sisal, nettle, and flax are much, much cheaper. A breakthrough in this application will revolutionize brake manufacture and protect the environment. 

Manufactured aramid fibres are usually treated by a binder such as oils and surfactants to protect the fibre surface and improve the ability to handle. In order to remove the binder the knitted fabric is immersed in... 

Cast PTFE films can be laminated with different substrates, most frequently with PTFE-coated glass and aramid fabrics. They also can be metallized, in particular with aluminum for use in electronics. Other applications include as release films for the manufacture of composite materials for aerospace vehicles, in electronics and electrical industries, as selective membranes, and in the chemical industry. 

Asbestos-reinforced organic binders (thermoplastics, duroplasts and elastomers) are widely utilized e.g. hardenable molding materials on the basis of asbestos-reinforced phenol or melamine resins for the manufacture of insulating components for combustion engines, components for electrical installations, cogwheels etc. Possible fiber substitutes are glass fibers, carbon fibers and other synthetic fibers (e.g. aramide fibers) and non-fiber fillers such as calcium carbonate, clay or talcum. 

Analogous para-isomers are obtained from p-chioronitrobenzene (29b). Thus animation with aqueous ammonia at 180 °C and 40 atmospheres gives p-nitroaniline (15a), a useful dye intermediate, manufactured by batch or continuous processes. With sodium sulfide, 4,4 -diaminodiphenyl sulfone (4,4 -sulfonyldianiline), also known as dapsone (32), is obtained, a product used in leprosy treatment and in the manufacture of aramides. 15a... 

The p-aryl amides are produced from terephthalic acid and p-phenylenediamine. They are noted for high strength and thermal resistance that arise from extensive conjugation and linear geometry that enhances chain orientation. High-strength fibers with similar properties can be manufactured from aramids and melamine. 

About half of the benzene produced as a chemical feedstock is for styrene production, followed by large fractions for phenol and cyclohexane-based products. As much as half of the toluene produced is converted to benzene, depending on the price and demand differential. The largest use of toluene itself is as a component of gasoline. Much smaller amounts are used as a solvent, or in the manufacture of dinitrotoluene and trinitrotoluene for military applications. Xylenes are also used in gasoline formulations and function as octane improvers like toluene. para-Xylene and o-xylene are the dominant isomers of value as chemical feedstocks, for the production of terephthalic acid (and dimethyl terephthalate) and phthalic anhydride, respectively. Polyester and the synthetic resin markets, in turn, are major consumers of these products. meto-Xylene is oxidized on a much smaller scale to produce isophthalic acid, of value in the polyurethane and Nomex aramid (poly(m-phenylene isophthalamide)) technologies. 

Wet layup consists of placing a layer of dry reinforcement inside a mold and then applying an uncured, low-viscosity thermoset resin as shown in Fig. 2. Woven glass fibers are the prevalent reinforcing preform utilized in layup processes, although carbon and aramid fibers are also used to a lesser extent. Typical fiber volume fraction of composites manufactured via wet layup range between 30% and 50%. The resin can be poured, sprayed, or brushed on top of the preform layer either by hand or by machine. The fiber preform layer is rolled on or pressed after the application of resin to evenly distribute the resin and remove air pockets. Resin is applied on top after each layer of fiber mats is properly placed. This process is repeated until the desired thickness is reached. To provide a smooth surface finish on the mold side, a thin layer of mold release is often applied prior to starting the layup. Thereafter, pressure and heat are applied to allow the composite to cure. Pressure can be applied... 

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