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 ?
They observed that polyvinyl siloxane and polysulphide were unaffected after immersion in sodium hypochlorite, 2 per cent glutaraldehyde, 0.
No zerovalent sulphur, such as polysulphides and/or elemental sulphur, was reported.
The process was simulated for SiC particles distributed uniformly in polysulphide epoxy resin under centrifugal force equivalent to 10 times that of gravitational force and is shown in Fig.
Alternatively, sulphur dioxide or sodium polysulphide can be used.
The EU Council of Ministers decided to drop anti-dumping measures imposed in 1998 on imports from the United States of polysulphide polymers (PSP) on February 11.
If the temperature drops below 285 [degrees] C (545 [degrees] F) the sodium, sulfur, and sodium polysulphide formed during electrolysis solidify and the battery can't supply sufficient power.
Tenders are invited for Providing Polysulphide Sealant Treatment In Expansion Joints in connection with Construction of 120 Mens Barrack I/C Sanitary Installation And Internal Water Supply, Internal El And Fans, Mcb.
The problem is that the reaction has a number of intermediate species--a series of polysulphide ions--which are soluble in the electrolyte.
The two lines, LVFPLN 3,500 mm x 2,500 mm and 5,000 mm x 2,500 mm, are empowered with a vertical edged deletion machine, a fully automatic plant for endless bent spacers and two fully automated dual adaptor robotic sealing machines capable of sealing double-glazed architectural units with silicon polysulphide or polyurethane as the case may be.
If they do contain heavy metal complexes, however, they are first subjected to batch treatment with sodium dithionite or polysulphide to break up the complex compounds.
Tenders are invited for Ammonium polysulphide as per tender document
According to a survey conducted in 1969 in US zinc oxide eugenol was the most popular (85%) final impression material for complete dentures6 but in 1993 a similar survey showed that 48% of the schools were using polysulphide as material of choice for complete denture final impression.