Rubber, polysulfide

Polysulfide rubbers possess excellent resistance to weathering and oils and have very good electrical properties. 

Polysulfide elastomer Polysulfide polymers Polysulfide process Polysulfidepulping Polysulfide rubbers Polysulfides... 

The counterpart of reaction (III) in polyesters, i.e., ester-ester interchange, probably does not take place to any appreciable degree. Polymeric polysulfide rubbers ( Thiokor type)... 

Uses Manufacture of insecticides, polymers degreasing solvent intermediate for polysulfide rubber. 

Uses. Intermediate in the manufacture of pesticides and polysulfide rubbers formerly used as a solvent and extractive agent... 

In 1931 Du Pont introduced the first synthetic elastomer, polychloroprene (Neoprene , Duprene ), and Thiokol Corporation introduced a polysulfide rubber called Thiokol . Polychloroprene, although veiy expensive compared to polyisoprene, has superior age resistance and chemical inertness. It is also nonflammable. 

Polysulfide polymers Polysulfide polymers increase the reactivity of some explosives and propellants. They are not compatible with PETN, Pentolite, Composition B, Amatol or Tetryltol. Polysulfide rubbers absorb some NG from DB and triple-base ( ) propellants. However, some propellants show little or no reactivity in the presence of polysulfides. 

These new synthetic rubbers were accessible from potentially low cost raw materials and generated considerable woddwide interest. For a time, it was hoped that the polysulfide rubbers could substitute for natural mbber in automobile tires. Unfortunately, these original polymers were difficult to process, evolved irritating fumes during compounding, and properties such as compression set, extension, and abrasion characteristics were not suitable for this application. 

Worldwide production capacity of liquid polysulfides is about 33,000 t with manufacturing sites in the United States, Japan, and Germany. Total consumption is about 28,600 t. Approximately 50% is for insulating glass sealants, 30% for construction applications, and 10% for aircraft sealants. In addition, 909 t of the solid polysulfide rubbers are sold each year. 

Barium Peroxide. The commercial product is a dull yellow powder containing about 90% Ba02 and about 8.5% active oxygen. The principal use is in pyrotechnics, but there are also small uses in the curing of polysulfide rubbers and in the production of certain titanium-aluminum alloys. 

The compn and props of the proplnt called in Ref lb, Thiokol, are as follows NH4C104 21.15, KC104 47.12, polysulfide rubber (Thiokol) 28.85 additives 2.88% its Isp 194 secs, burning rate 0.7in/sec, temp sensitivity 0.17%/°F, temp limits -50 to +160°F and smoke - heavy... 

Early in the development of solid propellant, the asphalt composites were found to have poor physical properties, such as cracking under normal temperature cycling, poor tensile characteristics, etc. They were replaced with the elastomeric polymers which have become the present-day binders. The first of these was Thiokol rubber, a polysulfide rubber, whichgives the propellant with good physical properties. The presence of the sulfur atom in the Thiokol rubber decreases the performance compared to a CHO polymer thus the most frequently used binders are polyurethane, polybutadiene acrylic acid (PBAA), epoxy resin, etc. The choice of the latter binders is made with regard to physical properties rather than performance. 

Manganese(IV) oxide is utilized as a depolarizer in dry batteries, in the manufacture of ferrites, as an oxidizing agent in organic synthesis, as a crosslinking agent for polysulfide rubbers and as a component of oxidation catalysts. 

Use Solvent for oils, fats, greases, resins, gums extractants, cleaning compounds intermediate for insecticides, pharmaceuticals, plasticizers, polysulfide rubbers, resins, and cationic surfactants. 

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

Significant developments in synthetic rubber began at this time. Outstanding were the introduction of polychloroprene (neoprene) by Carothers, and of the oil-resistant polysulfide rubber Thiokol by Patrick. These were soon followed by styrene-butadiene copolymers, nitrile rubber, butyl rubber, and various other types, some of which were rushed into production for the war effort in the early 1940s. The stereospecific catalysts researched by Ziegler and Natta aided this development, including synthesis of true rubber hydrocarbon (polyisoprene). Since 1935 synthetic rubbers have been referred to as elastomers. 

Elastomers include natural rubber (polyisoprene), synthetic polyisoprene, styrene-butadiene rubbers, butyl rubber (isobutylene-isoprene), polybutadiene, ethylene-propylene-diene (EPDM), neoprene (polychloroprene), acrylonitrile-butadiene rubbers, polysulfide rubbers, polyurethane rubbers, crosslinked polyethylene rubber and polynorbomene rubbers. Typically in elastomer mixing the elastomer is mixed with other additives such as carbon black, fillers, oils/plasticizers and accelerators/antioxidants. 

Polysulfide rubber Polyalkylene sulfide Metal oxides Fair Poor... 

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