Other Polyamides

The hterature notes many other polyamide hoUow fibers, none of which have achieved significant commercial success. Included in this category are such polymers (some of which are cross-linked) as piperazinamides, hydrazine, substituted acrylamide, and modified and grafted nylons. 

The two polymers appear to be well balanced, and future competitive pressure will almost assuredly come not from each other, but rather from other polyamides and, even more likely, from other polymers, such as low cost polyolefins and polyesters or high performance engineering resins. 

Other polyamides having higher moduli and T than nylon-6 and nylon-6,6 have been evaluated in an effort to reduce wrinkle resistance and eliminate flat-spotting of bias and bias-belted tires (Table 3). Nylons have also been tested extensively over the years for apparel and carpets (Table 4). 

C under nitrogen, the yield is 56% A/ AT-ethylenebisstearamide [110-30-5] (57). Other polyamides can be prepared from polyamines in a similar fashion. 

Other polyamides produced experimentally include polymers with active lateral groups (hydroxy, keto groups etc.), polymers with heteroatoms (sulphur and oxygen) in the polyamide-forming intermediates, polymers with tertiary amino groups in the main chain and polymers with unsaturation in the main chain. There does not, however, appear to have been any serious attempt to develop unsaturated polyamide analogues to the polyester laminating resins. 

Other polyamides can be made from different acids and other amines, giving a variety of properties suited to a variety of uses. 

Other polyamides employed include ethylene bisricinoleamide and ethylenediaminetallowdiamide. Alkanolamides such as coconut... 

U-pin is most comparable to a six-ring hairpin polyamide, likely due to a loss of two hydrogen bond donors upon removal of the y-turn element. Thus, the dimeric Py-lm U-turn element may be thought of as a C,G-specific replacement for the y-tum (Fig. 3.4). In combination with removal of the /9-Ala tail (see below), H-pin and U-pin polyamides could potentially bind purely G,C sites, a sequence type that has been difficult to target with other polyamide motifs. 

PVPP is commonly used to remove undesirable brown or pink pigments from wine (Jackson, 1994). However, because much of the color of red wine is due to polyphenolic compounds, treatment with PVPP or other polyamides can diminish the red color and so must be carefully controlled. Additions of gelatin or egg white (egg albumin has about... 

Turning now to the polyamides, Brill (1942) made x-ray measurements of the lattice constants of polyamides and found that in the case of 6-6 Nylon, the b lattice constant rose steadily from a value of 5.2 at —20° C to 5.8 at 161° where it then equalled the a lattice constant. In other polyamides, the b constant also rose with temperature, but the polymer melted before b became equal to a. 

The physicallydried binding agents include acrylic resins, polyesters, silicones, cellulose derivatives and others. Polyamides and polyolefins are used as raw material for powder lacquers. Differing from physically dried lacquers, chemically dried lacquers contain crosslinked macromolecules. The raw materials used as binding agents can in this case be used without solvents because of their low viscosities and react with the substrate by one of the above mentioned polymerization reactions. 

Electrical Properties. In its electrical insulating properties Trogamid T is similar to other polyamides. Its dielectric properties are not particularly striking. The electrical properties undergo slight change in relation to humidity, and prolonged water immersion has no appreciable... 

Moisture absorption affects the properties only to a small extent. However, the swelling ratio from water related to the absorbed water is smaller than for other polyamides. 

Similar relaxation phenomena are observed in other polyamide systems such as the protein collagen and the synthetic polypeptide 50/50... 

Polyureas, which are strictly speaking polyamides of carbamic acid (and which can indeed be prepared by reacting diamines with phosgene) differ in many ways from the other polyamides. This class of polymer is discussed briefly in Section 8. 

Nylon 9, which is extremely stable to heat, does not show even a slight change in the wide range of about 100° C. over its melting point. With this polyamide, unlike other polyamides, the molten polymer is driven directly to the spinneret after polycondensation. There is no monomer in the polymer to be washed out. These facts have simplified the process. 

Several other polyamides are derived from natural poly(amino acids) that are subject to a subsequent synthetic treatment. Examples are casein, groundnut protein fiber, and zein, which after a treatment with formaldehyde led to new materials with better mechanical/solubility properties. For example, casein is a mixture of several proteins that forms 3% of milk (as casein calcium salt). Casein can be fractionated into simpler proteins designated as a, 3, y, and k [37]. The amino acid content of casein is similar to... 

Chlorine resistance tests on FT-30 membranes, whether static-jar storage tests or dynamic tests with chlorine added to the feed-water showed a much lower rate of oxidation compared to other polyamide membranes such as the NS-lOO. A peculiar property of the FT-30 membrane in regard to chlorine attack was that the rate of oxidation was lowest in an acid pH range of 5 to 6 and higher in the... 

Utilization of a waste-product (2-methylglutaronitrile can be used as a co-monomer in the production of other polyamides, but the end-product niacin has an intrinsically much higher value). 

Other polyamides, not as important industrially as the above, can also be synthesized ... 

Since the polymers in this series are homologues, there is some justification for using a density comparison to determine relative amounts of free volume. Figure 4 shows that as n increases, the polyisophthalamide density decreases. Similar trends were observed by Ridgway in other polyamide series (11). This trend indicates that free volume is increasing with n and that permeation would be expected to increase, which is what in fact is observed. 

Of the wide variety of other polyamides based on aliphatic diamines and dlaclds, few have been commercialized for fiber application. A number, however, have been developed for commercial application in extruded and molded plastics. 

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