Polysulfide, aliphatic aromatic

An FAB-MS study on several aromahc, aliphatic, and aliphatic-aromatic polysulfides doped with heavy metal salts allowed the detection of adducts of the cyclic sulfides with heavy metal ions Ag, Hg, and Cu - The molecular ions of the cyclic sulfides and those corresponding to the metal adducts appeared in the spectra with widely differing intensities, providing a tool to investigate the selectivity of metals toward macrocyclic sulfides of different structure and size. ... 

Polysulfide 150 Excellent resistance to oils, gasoline, aliphatic and aromatic hydrocarbon solvents. Very good water resistance, good alkali resistance, fair acid resistance. Poor mechanical properties. 

The manufacture of sulfur dyes involves sulfurisation processes, the chemistry of which remains rather mysterious and may arguably be considered still to be in the realms of alchemy The processes involve heating elemental sulfur or sodium polysulfide, or both, with aromatic amines, phenols or aminophenols. These reactions may be carried out either as a dry bake process at temperatures between 180 and 350 °C or in solvents such as water or aliphatic alcohols at reflux or at even higher temperatures under pressure. C. I. Sulphur Black 1, for example, is prepared by heating 2,4-dinitrophenol with sodium polysulfide. 

Aliphatic iodine derivatives, 14 376 Aliphatic ketones, 14 563, 571, 581-585 reactions of, 16 331-332 Aliphatic monothiopolyesters, 23 739 Aliphatic nitration, 12 187 Aliphatic peroxyacids, 13 464 Aliphatic peroxycarboxylic acids, 18 463 Aliphatic phosphines, 19 60 Aliphatic polyamides (PA), 10 207-210 19 713, 739. See also Aromatic polyamides PA entries producers of, 10 210 properties of, 10 208, 209t Aliphatic polycarbonates, 24 703 preparation of, 19 798 Aliphatic polyketones (PK), 10 197 costs of, 10 222 properties of, 10 198t Aliphatic poly(monosulfide)s, 23 702-704 Aliphatic polyphosphonate dyes, 9 480 Aliphatic poly(polysulfide)s, 23 711 Aliphatic polysulfides, 23 734 Aliphatic polysulfoxides, 23 733 miscibility of, 23 735 Aliphatic polyurea preparation, carbonyl sulfide in, 23 625... 

Thiokol elastomers possess fairly low tensile and tear properties. However, they have excellent resistance to both aliphatic and aromatic solvents at room temperature and slightly elevated temperatures. The Thiokol division of Morton International Corporation is the supplier of polysulfide elastomers in the United States. It is estimated that 1360—1600 t are used annually in the United States. The primary use of polysulfide is in seals, gaskets, rolls, and diaphragms where solvent resistance and low permeability are useful. 

The liquid polymer is converted to the rubbery state by reagents that react with mercaptan (-SH) and side groups of the polymer segments by oxidation, addition or condensation to effect sulfide (-S-S-) bond formation. The oxidation reactions are exothermic and accelerated by an alkaline environment. The most commonly employed oxidizing agents which are suitable for curing liquid polymers are cobalt or manganese or lead octoate, p-quinonedioxime and di- or tri-nitrobenzene. Epoxy resin also reacts with liquid polysulfide polymers by addition in the presence of an aliphatic or aromatic amine and polyamide activator as shown in Equation 5.8 ... 

Suitable curatives for the polysulfide-epoxy reaction include liquid aliphatic amines, liquid aliphatic amine adducts, solid amine adducts, liquid cycloaliphatic amines, liquid amide-amines, liquid aromatic amines, polyamides, and tertiary amines. Primary and secondary amines are preferred for thermal stability and low-temperature performance. Not all amines are completely compatible with polysulfide resins. The incompatible amines may require a three-part adhesive system. The liquid polysulfides are generally added to the liquid epoxy resin component because of possible compatibility problems. Optimum elevated-temperature performance is obtained with either an elevated-temperature cure or a postcure. 

Various aliphatic and aromatic dichlorides and -bromides have been used to synthesize tri- and tetrasulfanes by reaction with aqueous or alcoholic sodium polysulfide. For instance, the benzotrithiepin (8) was obtained from... 

Polysulfide rubbers posses outstanding resistance to solvents. They exhibit excellent resistance to oils, gasoline, and aliphatic and aromatic hydrocarbon solvents, very good water resistance, good alkali resistance, and fair acid resistance. FA polysulfide rubbers are somewhat more resistant to solvents than ST rubbers. Compounding of FA polymers with NBR will provide high resistance to aromatic solvents and improve the physical properties of the blend. For high resistance to esters and ketones, neoprene W is compoimded with FA polysulfide rubber to produce improved physical properties. 

Various types of condensation polymers such as aromatic polysulfonates and polysulfides, aromatic polyethers, aliphatic and aromatic polysulfides, and carbon-carbon chain polymers of high molecular weights by the phase-transfer catalyzed polycondensation fi-om combinations of aromatic disulfonyl chlorides, phosphonic dichlorides, activated aromatic dichlorides, and aliphatic dihalides, withbisphenol, aliphatic and aromatic dithiols, and active ethylene compounds. The two-phase polycondensation was generally carried out in a water-immiscible organic solvent-aqueous alkaline solution system at room temperature. The method of polycondensation offers a highly versatile and convenient synthetic method for a variety of condensation polymers. 

Acrylic sealants are water-based but they may also contain ethylene and propylene glycols, mineral spirits and mineral oil. There are also solvent-based acrylic sealants which contain substantial amounts of solvents such as mineral spirits, toluene and xylene. Polysulfide sealants usually contain toluene but methyl ethyl ketone is also used. The group of class B sealants contains substantially more solvents (up to 40% by volume) but there are some exceptions. PVC sealants are based on plastisols and they can be made without solvents. Butyl rubber based sealants usually contain hydrocarbons (Q-C,2). Styrene-buta-diene-styrene based sealants usually have a large amoxmt of solvents selected from a group including toluene, heptane, hexane, methyl ethyl ketone, isobutyl isobutyrate, n-amyl acetate, n-amyl ketone. They are usually processed in solvent mixtures. Polychloroprene is usually dissolved in a mixture of solvents including ketones or esters, and aromatic and aliphatic hydrocarbons. The list includes naphtha, hexane, acetone, methyl ethyl ketone, benzene, and toluene. 

Polysulfides, whether aliphatic or aromatic, have excellent physical and chemical properties, which make them one of the leaders in petrochemical industries as elastomers and engineering thermoplastics. 

As has been indicated in a number of studies, sulfur-containing compounds give a synergic effect with amines and phenols in the stabilization of high-molecular compounds [89, 279]. The following have been proposed and are used as stabilizers of polyvinyl chloride mercaptides of antimony [280, 281], condensation products of aldehydes or ketones with mercaptans [63], thioesters [282], salts of thioacids [283], aromatic esters of aliphatic sulfonic acids [284], esters of xanthic acids [285] the use of the polysulfide of the composition... 

Since Activator 73 A is a mixture of zinc salts of linear aliphatic and aromatic carboxylic acids (50), it would be expected that the mechanism of action would be similar to zinc stearate, which can extract sulfur from polysulfidic cross-links and reuse that sulfur to generate more cross-links (51). Ultimately this would result in a network structure high in monosulfidic content (42). 

The polysulfides have an outstanding resistance to solvents, oils, gasoline, and aliphatic and aromatic hydrocarbon solvents, as well as very good water resistance. 

Ruororubbers and silicones are the best materials to make seals resistant to extreme temperature conditions. Viton, a fluororubber marketed by M/S Du Pont USA, can operate at 200°C in contact with oils and lubricants. Polysulfide rubbers have low compression set, but exhibit excellent fuel resistance. For improved compression set, it is admixed with relatively cheap conventional nitrile rubbers. The fluorine-containing rubbers, such as fluororubber, possess outstanding resistance to heat, fuels and hydraulic fluids coupled with extremely good aging characteristics. The reversible physical effects with respect to the ultimate tensile strength of this rubber vulcanizate is a noteworthy phenomenon since this is not associated with the deterioration of the rubber itself. Fluororubber is resistant to most fluids used in the aircraft industiy, such as synthetic, ester type lubricants, aromatic and aliphatic hydrocarbons, and water. 

Cured liquid polysulfide compositions have excellent resistance to a wide variety of oils and solvents, for example, aliphatic and aromatic hydrocarbons, esters, ketones, and dilute acids and alkalis. Table 3 shows the properties of two polysulfide oligomers cured with conventional filled formulations [36]. The data presented are only trends and not absolute, since the results depend on the efficiency of cure. Systems that are not properly compounded have poorer solvent resistance. 

This technique has been used to identify cyclic oligomers formed by polycondensation reactions leading to aromatic, aliphatic and aromatic-aliphatic polysulfides and their complexes with heavy metals [274]. 

Montaudo and co-workers [39] used fast atom bombardment mass spectrometry to identify the cyclic oligomers formed in the polycondensation reactions leading to the aromatic-aliphatic polysulfides. He also used the technique in microstructural studies on copolymers [40, 41]. 

Phase transfer catalyzed polycondensation was also applicable to the syntheses of aliphatic and aromatic polysulfides. For example, aliphatic polysulfide X from aliphatic dibromide VHI and aliphatic dithiol IX [Eq.(4)],8 aromatic polysulfide XII from activated aromatic dichloride VI and aromatic dithiol XI [Eq.(5)], and another type of polysulfide XIV from activated dichloride Xm and XI [Eq.(6)].10... 

Several types of hardeners are used in the curing Aliphatic amines Amidoamines Aromatic amines Cycloaliphatic amines Imidazoles Polyamides Anhydrides Polysulfides Mercaptans Dicyandiamide (DiCy)... 

The Willgerodt reaction is useful in the preparation of arylacetic acids and amides from substituted methyl aryl ketones or vinyl aromatic compounds. The aliphatics and acetylenes give lower yields. The conversion is effected by heating aromatic compounds at 160°-200°C in an aqueous solution under pressure using ammonium polysulfide. In the Kindler modification, the ketone or styrene is refluxed with a mixture of sulfur and an amine, usually morpholine, to give a thioamide, ArCHjCSNRj. 

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