Polysulfide

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Polysulfide

A thermosetting resin, used as a building sealant.

Polysulfide

 

a derivative of hydrogen polysulfide, H2Sx where x = 2–9. Polysulfides are solids, ranging in color from light yellow to brownish red, with a specific, unpleasant odor.

Polysulfides of ammonia, alkali metals, and alkaline-earth metals are known—for example, potassium forms K2S2, K2S3, K2S4, K2S5, and K2S6. Sulfur atoms are arranged in an —S—S—S— chain in polysulfide molecules. The melting point of polysulfides is lower than that of sulfides. For example, the melting point of K2S is 835°C, whereas that of K2S6 is 183°C. Polysulfides are chemically very unstable; they decompose upon heating to form sulfides. In the presence of acids they liberate H2Sx which decomposes immediately into H2S and S.

Polysulfides are produced by fusing sulfides, hydroxides, or carbonates with sulfur; sulfur may be added to an aqueous sulfide solution. Polysulfides of calcium and barium are used against agricultural pests. Barium polysulfide is an effective depilatory.

References in periodicals archive ?
Although this test enables us to determine the effects of the polysulfides on CE, this procedure does not quantify the polysulfides in the sample.
After this period, to the resulting natrium polysulfide mixture was added a solution of imidazolium salt (4 mL) in C[H.sub.2][Cl.sub.2].
Several researchers have demonstrated that various nanostructures can help trap the polysulfides within an electrode, but these designs run up against a second problem with lithium-sulfur batteries.
Au-amalgam microelectrodes are nonselective and can measure the concentrations and speciation in-situ of a suite of important redox species simultaneously, including dissolved [O.sub.2], [H.sub.2]S (MDL < 0.2 [micro]M), [S.sub.2][O.sub.3.sup.2-] (MDL 30 [micro]M), polysulfides ([S.sub.x.sup.2-], MDL < 0.2 [micro]M), (Brendel & Luther 1995, Luther et al.
Also available are cyanocrylate adhesives, anaerobic adhesives and sealants, films and preforms, poluurethane systems and polysulfides.
Precision meter, mix, and dispense systems for plural and single components, for use with silicones, polysulfides, polyurethanes, and epoxies.
* Polysulfides are exterior high-performance sealants available in one- and two-part formulations with a life expectancy of 25 to 50 years.
"My major approach involved polysulfides, which can increase the cellulose-hemicellulose yield in kraft pulping.
Spray with lime sulfur (calcium polysulfides) or fixed copper.
Widely used in plastic, paper, paint, and rubber industries, PCC is enjoying high consumption by manufacturers of PVC plastisols, polysulfides, urethanes, and silicones," the PMR analyst further adds.
These compounds are available as silicones, epoxies, polysulfides, polyurethanes, cyanoacrylates, and UV/LED curing systems.