Sulfonated polyamide

Polymeric membranes utilized for nano- and ultrafiltration applications are usually produced by the phase inversion process. Unlike in reverse osmosis, there is no continuous thin dense skin on the membrane surface. The membrane, however, has a tighter pore surface than the bulk of the membrane to allow the desired separation. The bulk of the membrane is much more open, to provide membrane support while limiting the resistance to water flux. Polymers employed in these membranes include polysulfone, poly(ether sulfone), polyacrylonitrile, poly(vinylidene fluoride), aromatic polyamides, sulfonated poly(ether sulfone), and cellulose acetate. 

Miscellaneous. In ore flotation, sodium sulfite functions as a selective depressant. In textile processing, sodium sulfite is used as a bleach for wood (qv) and polyamide fibers and as an antichlor after the use of chlorine bleach. Synthetic appHcations of sodium sulfite include production of sodium thiosulfite by addition of sulfur and the introduction of sulfonate groups into dyestuffs and other organic products. Sodium sulfite is useful as a scavenger for formaldehyde in aminoplast—wood compositions, and as a buffer in chrome tanning of leather. 

Acid—mordant dyes have characteristics similar to those of acid dyes which have a relatively low molecular weight, anionic substituents, and an affinity to polyamide fibers and mordant dyes. In general, brilliant shades caimot be obtained by acid—mordant dyes because they are used as their chromium mordant by treatment with dichromate in the course of the dyeing procedure. However, because of their excellent fastness for light and wet treatment, they are predominandy used to dye wool in heavy shades (navy blue, brown, and black). In terms of chemical constitution, most of the acid—mordant dyes are azo dyes some are triphenyhnethane dyes and very few anthraquinone dyes are used in this area. Cl Mordant Black 13 [1324-21 -6] (183) (Cl 63615) is one of the few examples of currentiy produced anthraquinone acid—mordant dyes. It is prepared by condensation of purpurin with aniline in the presence of boric acid, followed by sulfonation and finally by conversion to the sodium salt (146,147). 

Acid Dyes. These are anionic dyes, usually containing sulfonic acid groups, that are substantive to wool, other protein fibers, and polyamides when dyed from an acidic dyebath. The lower the pH the more rapid the dyeing, and exhaustion efficiency is enhanced by increased acidity. 

Direct Dyes. These are defined as anionic dyes, again containing sulfonic acid groups, with substantivity for ceUulosic fibers. They are usually a2o dyes (qv) and can be mono-, dis-, or polya2o, and are ia general planar stmctures. They are appHed to ceUulosic fibers from neutral dyebaths, ie, they have direct substantivity without the need of other agents. Salt is used to enhance dyebath exhaustion. Some direct dyes can be appHed to wool and polyamides under acidic conditions, but these are the exception. 

Typically RO systems are preceded by pretreatment units to remove suspended solids/colloidal matter and add chemicals that control biological growth and reduce scaling. Membranes are typically made of synthetic polymers coated on a backing (skin). Examples of membrane materials include polyamides, cellulose acetate and sulfonated polysulfone. 

The ester class also comprises natural oils, such as vegetable oil [75] spent sunflower oil [940,941,992,993] and natural fats, for example, sulfonated flsh fat [161]. In water-based mud systems no harmful foams are formed from partially hydrolyzed glycerides of predominantly unsaturated Ci6 to C24 fatty acids. The partial glycerides can be used at low temperatures and are biodegradable and nontoxic [1280]. A composition for high-temperature applications is available [1818]. It is a mixture of long chain polyesters and polyamides. 

M., Miyazaki, T., Tanihara, M., Sakaguchi, Y. and Konagaya, S. (2004) Coating of an apatite layer on polyamide films containing sulfonic groups by a biomimetic process. Biomaterials, 25, 4529 f534. 

Ikoma et al. carried out a detailed investigation to study the self-discharge mechanism and contribution of separators.They used nonwoven fabric made of conventional polyamide (FA), FF (with surfactant), and a nonwoven fabric whose main material was sulfonated-FF (hydrophilic) as separators. When nonwoven fabric made of chemically stable sulfonated-FF is used as a separator instead of a conventional polyamide separator, the self-discharge rate of the NiMH battery was strongly depressed, to the same level as that of NiCd battery. 2 >o-242.243... 

A new class of polyamides containing dibenzo 18-crown-6-moieties and alkaline units in the main chain shows [75] varying complexing capabilities with 4-toluene sulfonates of Rb+, K+, Na+ and potassium salts of CH3C6H4SOj, SCNI-, Br-. The polyamide polycondensates are obtained from cis- or trans-4,4 -diaminodibenzo 18-crown-6-(DAC) and a 4,4 -diearboxy-a, cu-diphenoxy-alkane (DCA) (Fig. 25). 

An early example of a monosubstituted stilbene was introduced by Geigy as Tinopal RBS (89) and used for cotton and polyamide (nylon). Conversion of the sulfonic acid group into A-ethylsulfonamide, via the sulfonyl chloride, yields an FBA for polyester and plastics (55USP2713057). The triazole ring is formed by diazotization of the 4-aminostilbene followed by coupling with 2-naphthylamine and oxidation with ammoniacal copper(II) sulfate, occasionally in pyridine (21CB2191). 

Branched phenol-formaldehyde condensates can be formed on a series of polyamides by heating the phenolic solution of the reactants up to 180° C in the presence of p-toluene sulfonic acid, with or without the addition of another solvent such as xylene, dimethyl sulfoxide or dimethyl formamide (7). 

Other monomers have been successfully grafted on polyamide under UV light sources. Hence, organic acids as acrylic (72,73), methacrylic (74), ftimaric (73), itaconic (73), and styrene sulfonic in 25% aqueous solution (73). Methyl acrylate and acrylamide in the presence of photosensitizers (74,75) and acrylonitrile (76) are reported as well. Heterocyclic derivatives as vinyl pyridine and vinyl pyrrolidone under UV light using photosensitizers as benzophenone were grafted on Nylon 66 cloth (77). 

Permeability of aromatic polyamide membranes have been improved by modification of aromatic rings with pendant polar groups, for examples sulfonic, carboxylic, carboxamide, and sulfonamide groups, in addition to the before-mentioned methoxy group. 

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