Polyamides water

PVP separation. The remaining pigment was removed from the polyamide water fractions by chromatography on a 2.4 cm x 15 cm column containing 50 g polyvinyl pyrollidone (Polyclar AT, GAF Corp., Wayne, N. J.) as shown in Figure 4. The PVP was rinsed first with 1 column volume of water followed by 1 column volume methanol. The p-damascenone charm of each fraction was then determined. The water rinses were concentrated on a 1 cm x 20 cm column containing 40 g of 40 mm C18 reversed phase adsorbant and eluted with 2 volumes of 50% methanol/water. The p-damascenone charm of the eluate was determined. 

In comparison with the efforts made towards achieving soluble yet thermally stable polyamides, many more studies are still needed in the field of lyotropic polyamides if anisotropic solutions in common organic solvents such as THF, chloroform etc. are to be achieved. This remains an interesting area for the fabrication of polyamides. Water soluble polyamides on the other hand, remain intriguing for some specific applications such as additives in the paper industry as described by Vandenberg [69]. 

Experimental Conditions I CeUulose chloroform-acetic acid-water (50-f- 45 4- 5). II Silica gel toluene-chloroform-acetone (40+ 25+ 35). Ill Polyamide benzene-butanone-methanol (60+ 20+ 20). IV Polyamide water-butanone-methanol (40 + 30 + 30). 

Another common reaction mechanism is condensation polymerization. The reaction between monomer units and the growing polymer chain end groups releases a small molecule, which is often water, as shown in Figure 1.2. This reversible reaction reaches equilibrium and halts, unless this small molecule by-product is removed. Polyesters (which have the by-product methanol) and polyamides (water is the by-product) are among the plastics made by this process. 

Amidation. Heating of the diammonium salt or reaction of the dimethyl ester with concentrated ammonium hydroxide gives adipamide [628-94-4] mp 228°C, which is relatively insoluble in cold water. Substituted amides are readily formed when amines are used. The most industrially significant reaction of adipic acid is its reaction with diamines, specifically 1,6-hexanediamine. A water-soluble polymeric salt is formed initially upon mixing solutions of the two materials then hea ting with removal of water produces the polyamide, nylon-6,6. This reaction has been studied extensively, and the hterature contains hundreds of references to it and to polyamide product properties (31). 

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. 

Other Uses. Large quantities of hydrocarbon resins are used in mastics, caulks, and sealants (qv). Polymers for these adhesive products include neoprene, butyl mbber, polyisoprene, NR, SBR, polyisobutylene, acryHcs, polyesters, polyamides, amorphous polypropylene, and block copolymers. These adhesives may be solvent or water-borne and usually contain inorganic fillers. 

Ink Types. There are 10 gravure ink types categorized by the binders or solvents used A, aUphatic hydrocarbon B, aromatic hydrocarbon C, nitrocellulose D, polyamide resins E, SS nitrocellulose M, polystyrene T, chlorinated mbber V, vinyls W, water-based and X, miscellaneous. 

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. 

Commonly used materials for cable insulation are poly(vinyl chloride) (PVC) compounds, polyamides, polyethylenes, polypropylenes, polyurethanes, and fluoropolymers. PVC compounds possess high dielectric and mechanical strength, flexibiUty, and resistance to flame, water, and abrasion. Polyethylene and polypropylene are used for high speed appHcations that require a low dielectric constant and low loss tangent. At low temperatures, these materials are stiff but bendable without breaking. They are also resistant to moisture, chemical attack, heat, and abrasion. Table 14 gives the mechanical and electrical properties of materials used for cable insulation. 

New water-insol. naphthalic acid imide dyestuffs - used to dye blends of polyamide or urethane- and polyester or tri acetate fibres having good light and washing fastness C91-110.342 RICH DE GB LI) ... 

Available Forms. Phthalocyanines are available as powders, in paste, or Hquid forms. They can be dispersed in various media suitable for aqueous, nonaqueous, or multipurpose systems, eg, polyethylene, polyamide, or nitrocellulose. Inert materials like clay, barium sulfate, calcium carbonates, or aluminum hydrate are the most common soHd extenders. Predispersed concentrates of the pigments, like flushes, are interesting for manufacturers of paints and inks (156), who do not own grinding or dispersing equipment. Pigment—water pastes, ie, presscakes, containing 50—75% weight of water, are also available. 

The second difficulty, degradation, required the development of a two-step polyamidation process following salt formation (157). During salt formation, tetramethylenediammonium adipate salt is formed in water solution at approximately 50% concentration or at a higher concentration in a suspension. As in nylon-6,6 manufacture, this salt solution, when diluted, permits easy adjustment of the stoichiometry of the reactants by means of pH measurement. 

Nylon-6 is the polyamide formed by the ring-opening polymerization of S-caprolactam. The polymerization of S-caprolactam can be initiated by acids, bases, or water. Hydrolytic polymerization initiated by water is often used in industry. The polymerization is carried out commercially in both batch and continuous processes by heating the monomer in the presence of 5—10% water to temperatures of 250—280°C for periods of 12 to more than 24 h. The chemistry of the polymerization is shown by the following reaction sequence. 

TrimeUitic anhydride is converted to PVC plasticizers, polyesters, water-soluble alkyd coatings, and polyamide—imide resias. The trimellitate plasticizers have a lower volatility than those derived from phthaUc anhydride (see Plasticizers). 

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