Commercialization nylon

Nylon. Nylons comprise a large family of polyamides with a variety of chemical compositions (234,286,287). They have excellent mechanical properties, as well as abrasion and chemical resistance. However, because of the need for improved performance, many commercial nylon resins are modified by additives so as to improve toughness, heat fabrication, stabiUty, flame retardancy, and other properties. 

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). 

Commercial engineering thermoplastic nylons are mainly crystalline resins. Nylon-6,6 [32131 -17-2] is the largest volume resin, followed by nylon-6 (48). Other commercially available but much lower volume crystalline nylons are -6,9, -6,10, -6,12, -11, and -12. The crystallinity of the molded part decreases with chain size (49). A few truly amorphous commercial nylon resins contain both aromatic and ahphatic monomer constituents (50). For example, Trogamid T resin is made from a mixture of 2,2,4- and 2,4,4-trimethylhexamethylenediamines and terephthahc acid (51). 

As may be expected from its structure, nylon 46 has a higher level of water absorption (about 14% in water at 23 °C) than any of the other commercial nylons... 

Self-lubricating grades are of particular value in some gear and bearing applications. One commercial nylon compound incorporates 0.20% molybdenum disulphide and 1 % of graphite whilst many other commercial compounds contain only one of these two lubricants. 

Figure 23.5 Chemical structure of repeat units of various commercial nylons a) nylon 11,b) nylon 12,c) nylon 46, d) nylon 610, and e) nylon 612...

Figure 6. Untreated and Treated Star-Nylon TGA Scans Relative to Commercial Nylon 6...

Nylon resins usually arc supplied in the form of cylindrical or rectangular diced pellets. Most commercial nylon molding, resins are... 

Some of the monomers commonly used to prepare the nylon resins are shown in Ihe accompanying table. Both petrochemical and vegetable products provide the source materials that are transformed into the reactive intermediates. Tile table correctly suggests that there is a wider choice in diacids than in diamines. The most important commercial polyamide resins are nylons-66 and -6. Other commercial nylons include 610, 612, 11, and 12. 

All nylons absorb some moisture from environmental humidity. Moisture absorption characteristics must be considered in designing and joining these materials. They absorb from 0.5 to 2 percent by weight of moisture after 24-h water immersion. Freshly molded objects contain less than 0.3 percent moisture since only dry molding powder can be successfully molded. Once molded, these objects absorb moisture when they are exposed to humid air or water. The amount of absorbed moisture increases until an equilibrium condition is reached based on the relative humidity of the environment. Equilibrium moisture contents of two commercial nylon resins for two humidity levels are as follows ... 

DuPont built the first commercial nylon plant in 1938. Although it was first used by the military to make parachutes, nylon quickly replaced silk in many common clothing articles after World War II. 

Fig. 12.8. N CP/MAS NMR spectra of commercial nylons (A) nylon 6, 10 annealed a-form (B) nylon 12 with y-crystal form (C) nylon 6, 10 sample melt-quenched and (D) nylon 11 containing predominantly a-crystal form.

The melting and glass transitions in commercial Nylons and both homo-and copolyamides prepared by interfacial polycondensation have been studied by DTA by Ke and Sisko (171). The ETTA curves for a number of the polyadipamides and polysebacamides are given in Figure 7.54. 

Table 1 shows some examples of our basic research and new businesses. Toray commercialized nylon 6 fiber In 1950. The raw material, -caploractam, was produced by a conventional multi step proress at that time, but it has been today completely replaced by my invention. The business of carbon fiber and advanced composite materials was the outcome of basic research on oi anic synthesis using phosphorous compounds in our Basic Research Laboratories. Investigation in holography provided a researcher with the idea to use a holograph as a memoi, and the world-first Kanji-Printer was introduced in 1974, even though the memory was later replaced by a semiconductor. Our pharmaceutical business was initiated from basic research on interferon and biotechnologies. In 1985 we... 

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