Nylon 6/9 physical properties

The physical properties of these fibers are compared with those of natural fibers and other synthetic fibers in Table 1. Additional property data may be found in compilations of the properties of natural and synthetic fibers (1). Apart from the polyolefins, acryhcs and nylon fibers are the lightest weight fibers on the market. Modacryhcs are considerably more dense than acryhcs, with a density about the same as wool and polyester. 

The film tube is collapsed within a V-shaped frame of rollers and is nipped at the end of the frame to trap the air within the bubble. The nip roUs also draw the film away from the die. The draw rate is controlled to balance the physical properties with the transverse properties achieved by the blow draw ratio. The tube may be wound as such or may be sHt and wound as a single-film layer onto one or more roUs. The tube may also be direcdy processed into bags. The blown film method is used principally to produce polyethylene film. It has occasionally been used for polypropylene, poly(ethylene terephthalate), vinyls, nylon, and other polymers. 

Nylon-6,6 [32131 -17-2J is a tough, translucent white, semiciystalline, high melting (T , = 265 C) material. The common physical properties ate shown in Table 9, and principal producers woddwide in Table 10, for nylon-6,6 and other commercial polyamides. 

Nylon-6 [25038-54-4] was first made in 1899 by heating 6-aminohexanoic acid (143), but its commercially feasible synthesis from caprolactam was discovered by Paul Schlack at 1. G. Farbenindustrie in 1938. Like nylon-6,6, it is a tough, white translucent, semicrystalline sofld, but melts at a lower temperature (T = 230° C. The physical properties and primary producers of nylon-6 are Hsted in Tables 9 and 10, respectively. 

Nylon-6,6 and nylon-6 have competed successfully ia the marketplace siace their respective commercial iatroductioas ia 1939 and 1941, and ia the 1990s share, about equally, 90% of the total polyamide market. Their chemical and physical properties are almost identical, as the similarity of their chemical stmcture might suggest the amide functions are oriented ia the same directioa aloag the polymer chain for ayloa-6, but are altematiag ia directioa for ayloa-6,6. 

Because of water s plasticizing effect, the water content of nylon fibers and fabrics must be known and controlled when measuring physical properties. Prior to the measurement, samples are conditioned at a specified temperature and rh for at least 24 h. 

Flame retardants designated for nylon include halogenated organic compounds, phosphorous derivatives, and melamine cyanurate (160—163). Generally, flame retardants are difficult to spin in nylon because of the high loading required for effectiveness and their adverse effects on melt viscosity and fiber physical properties. 

Amino resins react with ceUulosic fibers and change their physical properties. They do not react with synthetic fibers, such as nylon, polyester, or acryhcs, but may self-condense on the surface. This results in a change in the stiffness or resiHency of the fiber. Partially polymerized amino resins of such molecular size that prevents them from penetrating the amorphous portion of ceUulose also tend to increase the stiffness or resiHency of ceUulose fibers. 

Some of the common types of plastics that ate used ate thermoplastics, such as poly(phenylene sulfide) (PPS) (see Polymers containing sulfur), nylons, Hquid crystal polymer (LCP), the polyesters (qv) such as polyesters that ate 30% glass-fiber reinforced, and poly(ethylene terephthalate) (PET), and polyetherimide (PEI) and thermosets such as diaHyl phthalate and phenoHc resins (qv). Because of the wide variety of manufacturing processes and usage requirements, these materials ate available in several variations which have a range of physical properties. 

Weathering. This generally occurs as a result of the combined effect of water absorption and exposure to ultra-violet radiation (u-v). Absorption of water can have a plasticizing action on plastics which increases flexibility but ultimately (on elimination of the water) results in embrittlement, while u-v causes breakdown of the bonds in the polymer chain. The result is general deterioration of physical properties. A loss of colour or clarity (or both) may also occur. Absorption of water reduces dimensional stability of moulded articles. Most thermoplastics, in particular cellulose derivatives, are affected, and also polyethylene, PVC, and nylons. 

Hydrogen sulphide occurs naturally, e.g. in natural gas and petroleum, volcanic gases, and from decaying organic matter. It may be present near oil wells and where petroleum is processed. Commercially it is obtained as a by-product from many chemical reactions including off-gas in the production of some synthetic polymers (e.g. rayon, nylon) from petroleum products, and by the action of dilute mineral acids on metal sulphides. Physical properties are summarized in Table 9.14 and effects of temperature on vapour pressure are shown in Figure 9.5. 

The synthesis of well-defined LCB polymers have progressed considerably beyond the original star polymers prepared by anionic polymerization between 1970 and 1980. Characterization of these new polymers has often been limited to NMR and SEC analysis. The physical properties of these polymers in dilute solution and in the bulk merit attention, especially in the case of completely new architectures such as the dendritic polymers. Many other branched polymers have been prepared, e.g. rigid polymers like nylon [123], polyimide [124] poly(aspartite) [125] and branched poly(thiophene) [126], There seems to be ample room for further development via the use of dendrimers and hyperbran-... 

Table I SELECTED PHYSICAL PROPERTIES OF BA-CONTAINING NYLONS[10] PROPERTY N-13 N-13/13 N-11 N-6/10...

As indicated in Table I, most properties of polyamide derivatives of BA, nylons 13, and 13/13, are predictable from properties of commercial engineering plastics such as nylon-11 and nylon-6/10 -- the BA based nylons are have lower moduli and most physical properties are unexceptional.[9,10] However, the BA based nylons have one exceptional property -- their very low capacity to absorb moisture. This property suggests that these materials may be less affected by water plasticization than other nylons, and it has attracted interest in developing BA-based nylons commercially. Development has been impeded by the fact that BA is not produced on a sufficient scale to make it cost-competitive, and apparently the attractive markets are not large enough to justify investment in development of BA processes, creating a chicken-or-egg" problem. 

The DuPont research team turned from the synthesis of polyesters to tackle, more successfully, the synthesis of the first synthetic fiber material, nylon, which approached, and in some cases exceeded, the physical properties of natural analogs (Section 4.7). The initial experience with polyesters was put to good use in the nylon venture. 

TABLE 4.5 General Physical Properties of Nylon 6,6 and Nylon 6 ... 

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