Textiles Kevlar

The diaminobenzenes are made from benzene by a combination chlorination-nitration route although para-phenylene diamine is also made directly from aniline. orr/to-Phenylene diamine is widely used for the preparation of biologically active compounds such as fungicides and veterinarian medicines. The mera-diamine is used in fire-retardant textile fibers ( Nomex ) while the / ara-diamine finds use in high-strength textile fibers used for bullet-proof vests, sails, army helmets, and other types of fiber-reinforced plastics ( Kevlar ). 

Fibres are, as a result of the spinning process, molecularly oriented, and they have, therefore, a 2 to 3 times higher stiffness than the non-oriented polymer (e.g. polyamide and polyester textile fibres). With the highest attainable orientation, such as in aromatic polyamides (Twaron and Kevlar), and in the PE-fibre (Dyneema) the stiffness can be a hundred times higher than the one in the unoriented condition ... 

The largest commission finishers of fire-resistant textiles in the United stales tea 1995) are W extex and MF H Textiles. Inc. (Butler. Georgia). Specialized (lame-retardam applications to cotton-wrapped polyester. Kevlar, nylon, and glass core yams are beginning lo attract the interest of the industry for special-purpose fabrics. 

The use of Kevlar has been confined to specialised applications 98), where high mechanical performance and lightweight properties are essential, because of its present relatively high cost compared with conventional textile materials. These applications can be conveniently divided into two main categories, one where the fibres alone form the final product such as in cables and fabrics and the other where they act as reinforcing elements for the production of composite structures. 

Exploratory investigations (Freeman et al., 1991, 1993) of the use of more highly ordered polymeric precursors have shown that there remains considerable scope for the development of novel activated chars from synthetic textile fibres. For example, carbon dioxide breakthrough measurements revealed that activated carbons prepared from Kevlar interacted much more strongly with C02 than rayon-based chars. Thus, the latter showed very little ability to separate air and C02, in marked contrast to the Kevlar-derived materials. 

High performance polymer fibers (HPPF) have excellent mechanical properties compared to traditional textile fibers such as nylon. The typical HPPFs are aramid and polyethylene fibers (6). Aramid is a generic name for a class of aromatic polyamide fibers, most of which are varieties of poly(p-pheny-lene terephthalamide). Kevlar is the trade name of the varieties of aramid polymers introduced conunercially by Dupont. The molecules in the fibers of these materials are oriented in the axial direction. Poly(p-phenylene terephthalamide) is a rigid molecule with the following structure ... 

Quartz fibers and Kevlar have also been coated. A uniform adherent, conducting, and electroactive coating is produced using this simple approach. The mechanical properties of the base textile are not significantly affected. The authors suggest that the adherent coating arises from the fact that it is not the monomer or oxidant that is adsorbed onto the textile, but rather the radical and/or oligomers. 

Research and development in fluid jet technology led to its widespread use in film and web processing, mixers, reactors, and fiber processing. Applications to fibers alone includes Taslan bulked yams, jet piddlers, draw-jets, interlaced yams, bulk-crimped carpet fibers (BCF), and spunbonded products such as Reemay polyester, Typar polypropylene (PP), and Tyvek olefins. New fibers also were introduced Nomex aramid, especially suited for high-temperature applications Lycra spandex, an elastic textile yam Qiana nylon, with a silklike appearance and Kevlar aramid, used in products ranging from tires to bullet-resistant vests. 

The aramid fibres (Kevlar and Nomex are the trade names for two of the most common) are especially desirable for their strength-to-weight ratios being superior to metals. They are most often used in composites having polymer matrices (generally epoxies and polyesters). Since the fibres are relatively flexible and somewhat ductile, they may be processed by most common textile operations. 

Knopfle K Aramidfaser Kevlar und Zylon . Facharbeit an der Staatliehen Textil-fachschule Miinehbtag, 2000 weitere htformationen zu Zylon www.toyobo.eo.jp www. frenzelit.com... 

Sun D, Chen X. Plasma modification of Kevlar fabrics for ballistic apphcations. Textil Res /2012 l-7. 

There is also an opportunity to use fibre ropes as tension textiles in buildings. An example is a bus station in Cambridge, UK (Fig. 13.25), erected in 1991. The structure was designed with four masts, each with a pair of forestays and back stays to support the 7-metre cantilevered roof. The stays are made of Parafil ropes with a Kevlar core their function is primarily to resist snow loading, but they are permanently stressed to... 

Rayon fibers are used to prepare textile fabrics (paificulariy high fashion types), often in combination with cotton or polyester, in high fashion jeans, non wovens and special papers (e.g. tea bags). Once the mqor tire cord for both automotive and truck tires, it has been largely displaced by polyester in automotive tires and Kevlar in truck tires. This accounted for a major loss of demand for rayon. However, it is still used to a small extent in some automotive tires. 

Textile fibers such as nylon and Kevlar have been used extensively in protective garments for military personnel. Some of the important properties that... 

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