Polyamides textile fibers

Aramid fibers, i.e. polyamide textile fibers made from aromatic amines and dicar-boxylic acid [177] are similar to polyamide and polyester fibers and are highly heat resistant and flame retardant. Aramid fibers must be heat set by steaming before wet finishing and washed before dyeing for good leveling. 

The main uses for both nylon 6,6 and nylon-6 are in apparel, carpets, and industrial applications. In the area of general apparel, polyester has gained considerably in significant market segments at the expense of polyamides because of its easy-care characteristics. Polyamide textile fibers, however, will expectedly continue to be the principal materials for women s hosiery, intimate apparel, and certain stretch fabrics. It seems safe to conclude that the price to performance ratio will continue to secure a firm market position for polyamide fibers, even at increased feedstock prices. Primarily tire yarns in the developing countries will drive polyamide industrial fibers. 

The amide linkage characterizes nylons. In the first commercial nylon, nylon-6,6, R = (CH2 )g and R = (CH2 )4. Nylon-6,6 is familiar as a textile fiber (nylon stockings) and a molded plastic (see Polyamides). 

Other textile fibers include nylon, polyacrylonitrile, and ceUulose acetate (see Fibers, acrylic Fibers, cellulose esters Fibers, polyamide). 

The fiftieth anniversary of the announcement of nylon as the first synthetic organic textile fiber by the Du Pont Co. on October 27,1938 was celebrated as a significant event by the textile industry in 1988 (1,2). The announcement was the culmination of the fundamental research efforts of W. H. Carothers and his team at Du Pont (3). Carothers synthesized diamines from C2 to C18 in order for them to react with a variety of aliphatic dicarboxylic acids to make polyamides for evaluation as fibers (4—10). Alicyclic and aromatic diamines and dicarboxylic acids were also included. Nylon-6,6 was ultimately selected for scale-up and development because of its favorable melting point ( 260° C), best balance of properties, and lower manufacturing cost. The pilot plant for nylon-6,6 was completed in Wilmington, Delaware, in July, 1938, and a product was introduced on the market as Exton brisdes for Dr. West s toothbrushes (2). The first nylon filament plant was built in 1939 at Seaford, Delaware, and nylon stockings went on sale on October 24,1939 only to residents of Wilmington, and then nationally, on May 15, 1940 (2). 

Corrections of the apparent crystallinity values of fibers materials have been carried out by taking into account a disorder parameter k, following Ruland s method. Peculiar care was taken about samples preparation (cutting and pelleting of fibers), data collection and reduction, which will be briefly described. Crystallinity and disorder parameter measurements have been performed on main textile fibers (polyester, polyamide, aramid, polypropylene, cellulosic fibers) and the results will be discussed comparatively, with those got by more conventional x-ray crystallinity determinations. The complementarities of these different approaches will be illustrated with several examples. For instance,... 

Nylon. In 1939 the DuPont Company introduced the first truly synthetic textile fiber. Dr. Wallace Carothers invented nylon as a result of his basic research into polymer science. Chemically, nylon is a polyamide fiber. The two major types of nylon polymer are used in textiles type 6,6 which is made by using hexam-ethylene glycol and adipic acid, and type 6, which is made by polymerizing e-caprolactam. Nylon fibers are made by melt-spinning the molten polymer. The result is a continuous filament fiber of indeterminate length. It is spun in many deniers, with its diameter varying from 10 to 50 microns. The cross-section usually is round, trilobal, or square with hollow channels when used as carpet fiber. 

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 ... 

Polyamides of this kind are widely used as textile fibers for wearing apparel, as cord for reinforcement of heavy-duty tires, and in a myriad of molded objects which can replace metal parts. 

Polyamides are produced under a variety of trade names, the most popular of which are Nylons (Nylon 6, etc.) manufactured by DuPont. Although the polyamides find their greatest use as textile fibers, they can also be formulated into thermoplastic molding compoimds with many attractive properties. Their relatively high price tends to restrict their use. 

Vinyl polymers and condensation polymers were studied for the production of synthetic fiber. In 1932, Carothers and Hill of Du Pont studied linear aliphatic polyester and showed that fibers of sufficiently good mechanical properties are obtained by melt-spinning and colddrawing [8]. Polyester fiber was considered unsuitable as a commercial fiber because it has a low melting point and hydrolyzes easily with water. Carothers therefore turned his investigation from polyester to polyamide, and, in 1938, Du Pont announced the success of a new fiber called nylon. In Japan, studies to produce textile fibers from PVA began in 1938 and were intensively promoted. 

Three billion pounds of nylon and related polyamides are produced annually. About 60% of that total goes to make the nylon fiber used in home furnishings such as carpet. The remainder is used largely as a textile fiber in clothing (shirts, dresses, stockings, underwear, etc.) and as tire cord. Minor but important uses include fasteners, rope, parachutes, paintbrushes, and electrical parts (see I Figure 6.4). In medicine, nylon is used in specialized mbing. Nylon sutures were the first synthetic sutures and are still used. 

Uses Epoxy curing agent intermediate for mfg. of nylon, plastics, urethane coatings isocyanates petrol, additive adhesives polyamides for printing inks, dimer acids, textiles fibers paints lubricant additive scale/corrosion inhibitor water treatment chemicals... 

Polyamides are used as fibers and in construction. Aliphatic polyamides are mostly used as textile fibers, whereas certain aromatic polyamides are used as industrial fibers. Polyamide fibers with at least 85% of the amide groups joined to two aromatic rings are also known as Aramide fibers. 

Polyamide 6,6 is used as a textile fiber polyamide 6,10 and 6,12 are used as thermoplastic materials. Polyamide 13,13 production is uneconomic at present since the press cake obtained in producing the crambe oil has no commercial outlet. It cannot be used as animal feed since the taste is carried over to milk and eggs. 

Co. technical and high-performance textiles, from polyester and polyamide. Detailed fiber specifications... 

These first polyester fibers had melt transitions (T ) too low for use as textile fibers, and they were not investigated further. Carothers then turned his attention to the reactions of dicarboxylic acids and diamines to form polyamides and, in 1934, synthesized nylon 66, the first purely synthetic fiber. Nylon 66 is so named because it is synthesized from two different monomers, each containing six carbon atoms. 

Dr. Rudy Pariser, a Du Pont researcher, suggested that we try using biftinctional monomers, such as those used in polyesters and polyamides, to create a chemistry that was economically viable and might be functionally similar to the urethane. At the same time, similar work was being done by our Textile Fibers research group in search for a new elastic fiber. 

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