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 ?
--2-component sealants B and C (polyurethane) and sealant D (polysulphide) performed well in the weatherability test.
They observed that polyvinyl siloxane and polysulphide were unaffected after immersion in sodium hypochlorite, 2 per cent glutaraldehyde, 0.5 per cent povidone-iodine and 0.16 per cent halogenated phenol whilst polyethers were significantly unstable.
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.
Besides, there are many farms and some polysulphide ore smelters inside this National Park.
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.
Accurate replication of tooth preparations and their arch positions require impression materials that exhibit good dimensional stability.5 Elastic impression materials like hydrocolloid, polysulphide, condensation silicone, polyvinylsiloxane and polyether have been used for fixed partial dentures.Although alginate hydrocolloid is a popular impression material majority of dentists avoids this material due to its poor dimensional stability and unsatisfactory details.3
Polyurethane, polysulphide, and other acrylic polymers are among the popular waterproofing chemicals used in the market.
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.