Stabilized polymeric sulfur

Stabilized insoluble sulfur Insoluble sulfur Amorphous sulfur Stabilized amorphous sulfur Polymeric sulfur Stabilized polymeric sulfur... 

Use Antioxidants, fungicides, oil additives, plasticizers, insecticides, stabilizers, polymerization modifiers, stabilizer in tin-sulfur compounds, stripping agent for polysulfide rubber. 

Polymeric sulfur is produced commercially as insoluble sulfur (IS) and is used in the rubber industry [56] for the vulcanization of natural and synthetic rubbers since it avoids the blooming out of sulfur from the rubber mixture as is observed if Ss is used. The polymeric sulfur (trade-name Crys-tex [57]) is produced by quenching hot sulfur vapor in liquid carbon disulfide under pressure, followed by stabilization of the polymer (against spontaneous depolymerization), filtration, and drying in nitrogen gas. Common stabilizers [58] are certain olefins R2C=CH2 like a-methylstyrene which obviously react with the chain-ends (probably -SH) of the sulfur polymer and in this way hinder the formation of rings by a tail-bites-head reaction. In this industrial process the polymer forms from reactive small sulfur molecules present in sulfur vapor [59] which are unstable at ambient temperatures and react to a mixture of Ss and on quenching. 

S the thermal behavior of depends on its preparation since is a mixture of long chains and large rings and not a well defined chemical substance. This mixture is thermodynamically unstable with respect to a-Ss at 20 °C and in fact depolymerizes slowly at moderate temperatures already. DSC measurements of polymeric sulfur prepared from quenched melts as well as from sublimed sulfur show the polymer to melt at 100 °C followed immediately by the exothermic depolymerization. Stabilized commercial polymeric sulfur (Crystex) starts to melt only at 110 °C but otherwise behaves similarly (heating rate 10 K min ) [55]. 

ACIDE CYANHYDRIQUE (French) (74-90-8) Can be self-reactive, forming an explosive mixture with air (flash point 0°F/— 18°C). Unless inhibited, material stored more than 90 days may be hazardous. Heat above 356°F/180°C or contact with alkalis or amines can cause explosive polymerization. Violent reaction with strong oxidizers, acetaldehyde. Solutions containing more than 2—5% water are less stable than dry material. Acid solutions react with ammonia, ferric oxide, halogens, ozone. Attacks some plastics, rubber, and coatings. Water solutions attack carbon steels at room temperatures and stainless steels (especially if stabilized with sulfuric acid) above 176°F780°C. 

Acetic acid, mercapto- isooctyl ester A13-26088 EINECS 246-613-9 HSDB 2704 Isooctyl mercaptoacetate Isoootyl thioglycolate Mercaptoacetic acid, isoootyl ester, NSC 9590, Antioxidants, fungicides, oil additives, plasticizers, insecticides, stabilizers, polymerization modifiers, stabilizer for tin-sulfur compounds, stripping agent for polysulfide rubber. Sock, Bruno Chemische FabrikKG. 

One main problem, hampering the technical applications of organic conducting polymers up to now, is their environmental and thermal instability. Metal ions can be introduced to stabilize polymeric backbones. Because of the enormous coordinating ability of sulfur to many transition metal ions, a polymeric carbon-sulfur backbone, similar to BEDT-TTF and TTF units, was used in order to obtain coordination polymers. 

Rubber. The mbber industry consumes finely ground metallic selenium and Selenac (selenium diethyl dithiocarbamate, R. T. Vanderbilt). Both are used with natural mbber and styrene—butadiene mbber (SBR) to increase the rate of vulcanization and improve the aging and mechanical properties of sulfudess and low sulfur stocks. Selenac is also used as an accelerator in butyl mbber and as an activator for other types of accelerators, eg, thiazoles (see Rubber chemicals). Selenium compounds are useflil as antioxidants (qv), uv stabilizers, (qv), bonding agents, carbon black activators, and polymerization additives. Selenac improves the adhesion of polyester fibers to mbber. 

Under certain conditions hydrogen cyanide can polymerize to black soHd compounds, eg, hydrogen cyanide homopolymer [26746-21-4] (1) and hydrogen cyanide tetramer [27027-02-2], C H N (2). There is usually an incubation period before rapid onset of polymer formation. Temperature has an inverse logarithmic effect on the incubation time. Acid stabilizers such as sulfuric and phosphoric acids prevent polymerization. The presence of water reduces the incubation period. 

Chemical Reactivity - Reactivity with Water No reaction Reactivity with Common Materials Attacks rubber and most fibrous materials. May cause ignition of organic materials such as wood. Some acids, such as sulfuric acid, may result in explosion Stability During Transport Stable Neutralizing Agents for Acids and Caustics Not pertinent Polymerization Not pertinent Inhibitor of Polymerization Not pertinent. 

Thionyl imide, HNSO, is a thermally unstable gas, which polymerizes readily. It can be prepared by the reaction of thionyl chloride with ammonia in the gas phase. Organic derivatives RNSO have higher thermal stability, especially when R = Ar. The typical synthesis involves the reaction of a primary amine or, preferably, a silylated amine with thionyl chloride. A recent example is the preparation of FcNSO (Fc = ferrocenyl) shown in Eq. 9.8. In common with other thionylimines, FcNSO readily undergoes SO2 elimination in the presence of a base, e.g., KO Bu, to give the corresponding sulfur diimide FcNSNFc. 

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