The Nylon Series

The wettability band for polyamides of the nylon series shifted to show lower slopes and higher critical surface tension intercepts when plotted in the standard Zisman format (7) as the amide group density increased (JO). Unfortunately no theoretical work describes the important factors influencing the slope of such plots which reflect in a general way the strength of solid/liquid interactions. 

Polyamides contain the amide group, —NH—CO—, in the main chain. They can be subdivided into two series. The monomeric unit and the repeating unit are identical in the Perlon series, but two monomeric units form one repeating unit in the Nylon series ... 

The synthesis of polyamides of the nylon series has the advantage that the fraction of monomers and oligomers at the polycondensation equilibrium is very small. Consequently monomers and oligomers do not have to be removed from the polyamide, which is in contrast to polyamide production by lactam polymerization. On the other hand, the nylon polycondensation is not as straight-forward a process as the lactam polymerization. For historical reasons, PA 6,6 dominates the market in England and the USA, whereas in West Germany and Japan, PA 6 plays the dominant role. 

What are known as versamides also belong to the nylon series. Versamides are obtained by polycondensation of the ester groups of polymerized vegetable oils with diamines and triamines. The products are of low-to-medium molar mass with good solubilities and having melting temperatures between room temperature and 185°C. Hard versamides are... 

Polyamides contain the amide group —NH—CO— and can be classified in two homologous series. In the Perlon series, monomeric and repeat units are identical, since these polyamides occur either by the polymerization of lactams (cyclic amides) or the polycondensation of co-amino carboxylic acids. In contrast, the polyamides in the Nylon series are formed by the poly condensation of diamines and dicarboxylic acids Thus, two monomeric units form one repeat unit. 

In the nylon series, there are only three polymers that are of large-scale significance commercially nylon 6,6, nylon 6,10, and nylon 6,12. 

For several decades, nylons 6 and 6,6 have been virtually the only nylons widely u%d on an industrial scale. It was not until recently that some other members of the nylon series — from nylon 4 to nylon 12 — became an object of increased interest. 

The study of binary polymer-salt systems - in addition to its interest as a tool for elucidating the physical chemistry of the interaction - has indicated relevant implications bearing on the processing of synthetic polar polymers. The depression of the melting temperature for polyamides of the nylon series (21) due toO.OSLiCl mole fraction is exhibited in Figure 2. TheTncrea-... 

Table 6.2 illustrates the variation in T and some other properties with n for some commercial members of the nylon series. 

First, the nylon-salt-type monomers such as XPME [20], XTPE [21, 22], and ODPME [23] with exactly 1 1 composition were prepared from a series of aliphatic diamines (X standing for the number of methylene unit) or aromatic bis(4-aminophenyl) ether (ODA) and the corresponding aromatic tetracarbox-ylic acid half diesters (diacid-diesters) such as pyromellitic acid diethyl ester (PME) and 3,3",4,4"-p-terphenyltetracarboxylic acid diethyl ester (TPE). 

Changes in the crystallization behavior of the thermoplastic phase of the IPN have been observed in DSC (differential scanning calorimetry) experiments (i3). In Figure 7, a series of DSC scans on silicone-nylon 6,6 composites of various silicone contents are presented. The characteristic melt peak of the nylon matrix is observed in all of the thermograms, but a second, slightly lower temperature melt peak becomes more pronounced as the concentration or the cross-link density of silicone polymer in the IPN is... 

Perhaps the most convenient and presently accepted method of determining bacterial MICs, however, is the E (Epsilometer)-test. Basically this is performed in a similar manner to the disc test except that nylon strips that have a linear gradient of antimicrobial lyophilized on one side are used instead of the filter-paper impregnated antimicrobial discs. On the other side of the nylon strip are a series... 

The dynamic modulus curves from torsion pendulum data (14) are reproduced in Figure 5 and show complex modulus (G ) as a function of temperature for a series of NBCs ranging in polyether content from 0 to 66%. The curves representing 9 and 18% polyether copolymers are quite similar to, but not identical with nylon 6, which is shown in the dashed curve. The copolymer curves show a deflection at -60°C, the tg for polyether. This deflection becomes much more pronounced while changes in the nylon tg region at 45 to 50°C are not apparent. 

Figure 3. Crack growth rate vj. stress intensity factor range for the remaining Series B nylon 66 specimens...

To take advantage of this process for powder coating, a spray gun can be constructed without a high-voltage power supply. For most coating materials, the ideal material for gun construction would be PTFE since it is positioned at one extreme of the triboelectric series. However, for fluorpolymers, a gun constucted of nylon is best. Nylon is the engineering plastic that is furthest away from PTFE in the triboelectric series, so it provides the best charging of a fluoropolymer powder. The interior of the powder gun is constructed of nylon such that there... 

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