Polyamides, additives

Many properties of polyamides are attributable to the formation of hydrogen bonds between the NH and CO groups of neighboring macromolecules. This is evidenced by their solubility in special solvents (sulfuric acid, formic acid, m-cresol), their high melting points (even when made from aliphatic components), and their resistance to hydrolysis. In addition, polyamides with a regular chain structure crystallize very readily. 

Polyalkylene polyamines find use in a wide variety of applications by virtue of their unique combination of reactivity, basicity, and surface activity. With a few significant exceptions, they arc used predominantly as intermediates in the production of functional products. End-use profiles for the various ethyleneamines include fungicide, oil and fuel additives, polyamides/epoxy curing, paper resins, chelaiing agents, fabric sofieners/surfactanls, petroleum production, bleach activator, and anlhelmimics/pharmaceulicals. 

WO 98/29530 07/1998 Randall et al.l Procter Gamble Laundry detergent compositions containing fiber reactive additives (polyamide-polyamines) to improve fabric appearance and integrity... 

Dytek A. PuPont] 2-Methylpenta-methylene diamine epoxy curing agent also used in polyurethanes, wet strength resins, scale and corrosion inhibitors, gasoline additives, polyamide plastics, fflms, adhesives, and ii. ... 

Beilstein Handbook Reference) BRN 1732701 Dytek A EINECS 239-556-6 2-Methyl-1,5-pentanediamine 2-Methylpentamethylenediamine 2-Methylpentane-1,5-diamine 2-Methylpentanediamine 1,5-Pentanediamine, 2-methyl-. Epoxy curing agent also used in polyurethanes, wet strength resins, scale and corrosion inhibitors, motor oii and gasoiine additives, polyamide plastics, fiims, adhesives, and inks. Liquid mp = -50 - -60° bp = 193° d n 0.86 LD50 (rat orl) = 1690 mg/kg. DuPont. 

Another way of achieving permanence is the incorporation of biocidal groups into the polymer molecules, instead of using additives. Polyamides can be covalently bonded to N-chlorinated hydantoin to achieve protection against pathogenic microorganisms. 

In addition to blocking of the terminal groups, Kern and Cherdron proposed that the monomeric formaldehyde evolved durii decomposition be bonded by suitable additives (polyamides, urea, etc.), in order to prevent its oxidation to formic acid, which promotes acidolytic cleavage of the polymer macromolecules. 

Figure 6 shows some examples of wet strength decay for paper made with neutral oxidized guar or a typical wet strength additive (polyamide-amine epichlorohydrin resin, PAE), and a control without any additive. 

In the case of polyamides, this recycling technique is unfavorable (Table 3). Additionally, polyamides exhibit the excellent feature that, even after reprocessing, their properties are still relatively high, making them attractive for use as engineering plastics [18]. However, one should bear in mind that incineration is the simplest way of waste utilization, and the combustion energies of plastics are comparable to or higher than that of coal. 

Condensation polymers such as polyesters and polyamides are especially well suited to this method of molecular weight determination. For one thing, the molecular weight of these polymers is usually less than for addition polymers. Even more pertinent to the method is the fact that the chain ends in these molecules consist of unreacted functional groups. Using polyamides as an example, we can readily account for the following possibilities ... 

The thermal protection system of the space shutde is composed mainly of subliming or melting ablators that are used below their fusion or vaporization reaction temperatures (42). In addition to the carbon-carbon systems discussed above, a flexible reusable surface insulation composed of Nomex felt substrate, a Du Pont polyamide fiber material, is used on a large portion of the upper surface. High and low temperature reusable surface insulation composed of siHca-based low density tiles are used on the bottom surface of the vehicle, which sees a more severe reentry heating environment than does the upper surface of the vehicle (43). 

Quality Specifications. Because of the extreme sensitivity of polyamide synthesis to impurities ia the iagredients (eg, for molecular-weight control, dye receptivity), adipic acid is one of the purest materials produced on a large scale. In addition to food-additive and polyamide specifications, other special requirements arise from the variety of other appHcations. Table 8 summarizes the more important specifications. Typical impurities iaclude monobasic acids arising from the air oxidation step ia synthesis, and lower dibasic acids and nitrogenous materials from the nitric acid oxidation step. Trace metals, water, color, and oils round out the usual specification Hsts. 

When drawdown is high, the film may be uniaxially oriented and the properties of the final film isotropic. In the manufacture of strapping tape this effect is accentuated. If the cast or quenched film is to be used to feed an orientation tine, additional attention must be given to the amorphous—crystalline nature of the film ia the draw processes so that maximum strength can be achieved and uniform gauge and optical quality maintained. Slot casting is used for the orientation of these resins, polyesters, polyamides, and a variety of others. 

The materials of attention in promoting fire safety are generally organic polymers, both natural, such as wood (qv) and wool (qv), and synthetic, nylon (see Polyamides), vinyl, and mbber (qv). Less fire-prone products generally have either inherently more stable polymeric stmctures or fire-retardant additives. 

An alternative polymerization process utilizes a slurry of calcium chloride in NMP as the polymerization medium. The solubiHty of calcium chloride is only 6% at 20°C however, the salt continues to dissolve as conversion of monomers to polymer proceeds and calcium chloride/polyamide complexes are formed. Polymer molecular weight is further increased by the addition of /V, /V- dim ethyl a n i1 in e as an acid acceptor. This solvent system produces fiber-forming polymer of molecular weights comparable to that formed in HMPA/NMP. 

In addition to polyamide, lamination inks ordinarily contain modifiers such as polyketone resin, plasticizer, and wax to impart specific properties such as block resistance and increased bond strength. Because laminating inks are usually reverse-side printed and end-up sandwiched between films, gloss is not a primary requirement. Water-base laminating inks that will meet the U.S. EPA emission requirements and have the correct functional properties are currently under development. 

Without other alternatives, the carboxyalkyl radicals couple to form dibasic acids HOOC(CH)2 COOH. In addition, the carboxyalkyl radical can be used for other desired radical reactions, eg, hydrogen abstraction, vinyl monomer polymerization, addition of carbon monoxide, etc. The reactions of this radical with chloride and cyanide ions are used to produce amino acids and lactams employed in the manufacture of polyamides, eg, nylon. 

In addition to References 11 and 12, price and volume information concerning polyamides can be found in various pubflc sources (14) and private databases that requite a cHent fee for access (15). 

Other Preparative Reactions. Polyamidation has been an active area of research for many years, and numerous methods have been developed for polyamide formation. The synthesis of polyamides has been extensively reviewed (54). In addition, many of the methods used to prepare simple amides are appHcable to polyamides (55,56). Polyamides of aromatic diamines and aUphatic diacids can also be made by the reaction of the corresponding aromatic diisocyanate and diacids (57). 

Lewis acids, such as the haUde salts of the alkaline-earth metals, Cu(I), Cu(II), 2inc, Fe(III), aluminum, etc, are effective catalysts for this reaction (63). The ammonolysis of polyamides obtained from post-consumer waste has been used to cleave the polymer chain as the first step in a recycle process in which mixtures of nylon-6,6 and nylon-6 can be reconverted to diamine (64). The advantage of this approach Hes in the fact that both the adipamide [628-94-4] and 6-aminohexanoamide can be converted to hexarnethylenediarnine via their respective nitriles in a conventional two-step process in the presence of the diamine formed in the original ammonolysis reaction, thus avoiding a difficult and cosdy separation process. In addition, the mixture of nylon-6,6 and nylon-6 appears to react faster than does either polyamide alone. 

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