Elastomers polysulfide rubber

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

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. 

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 rubbers are manufactured by combining ethylene (CH2=CH2) with an alkaline polysulfide. The sulfur forms part of the polymerized molecule. They are also known as Thiokol rubbers. In general, these elastomers do not have great elasticity, but they do have good resistance to heat and are resistant to most solvents. Compared to nitrile rubber, they have poor tensile strength, a pimgent odor, poor rebound, high creep imder strain, and poor abrasion resistance. 

Polymers Resins I Butyl Rubber, Epichlorohydrin Elastomers, Ethylene Propylene Rubber, Hypalon (TM) Production, Neoprene Production, Nitrile Butadiene Rubber, Polybutadiene Rubber, Polysulfide Rubber, Styrene-Butadiene Rubber Latex 07/31/97... 

A series of these rubbers possess polar groups consequently, the corresponding elastomers do not swell in oil. Polyurethane rubbers and polysulfide rubbers, as well as the already mentioned nitrile and chloroprene rubbers (Table 37-5), belong to the good oil-resisting rubbers. Moderate oil resistance with simultaneously improved heat resistance is shown by chlorosulfonated ethylene, acrylic, silicone, and fluorine rubbers. 

Uses of Polysulfide Rubbers. Polysulflde elastomers are used in roller covering applications, hose liners, and solvent- and oil-resistant molded goods. The sealants are used in construction and in aerospace industries. 

Hydrolysis has been established for epoxy, polyurethane, and cyanoacrylate resins. In the case of conventional elastomers, polysulfides, polyurethanes, and acrylic rubbers have all shown sensitivity to moisture. Hydrolysis causes the breaking of bonds within the polymer. Thus the strength decreases. However, before this occurs the part usually swells and may cause deformation before hydrolysis can completely act. For electronic sealants and casting materials, it is highly desirable to keep moisture from penetrating into critical areas. Hydrophobic polymers have been... 

A curable epoxy resin containing a crosslinked elastomeric latex " yields a special type of sequential IPN. The elastomers mentioned include SBR, EPR, NBR, silicone rubber, and PEA. Hawkins " described an epoxy/polyurethane semi-SIN, and Mendoyanis " revealed an epoxy/liquid rubber SIN. The liquid rubbers were based on polysulfide rubber or polyethylene. The final products could be extended to 400% at... 

Special-Purpose Elastomers. Polychloroprene and polysulfide rubber were the first synthetic specialty elastomers discovered. Since their invention in the 1930s the total number of classes of synthetic rubbers has grown to almost 30. Table 1 has listed standard acronyms by the International Institute of Synthetic Rubber Producers (12). 

Synthetic rubber), for example, acrylate, acrylate-butadiene, butyl, ethylene-propylene, chloroprene, ethylene-propylene diene, latex, neoprene, nitrile-butadiene, polyisobutylene, polysulfide, silicone, styrene-butadiene, styrene-isoprene rubber thermoset vulcanizable elastomers thiol rubber urethane... 

TR n Thermoplastic elastomers. Abbreviation used by British Plastics Institution for Thio Rubber. See Polysulfide Rubber. 

ST polysulfide rubber is a millable gum elastomer prepared from bis (2-chloroethyl) formal and sodium polysulfide. Vulcanizates exhibit outstanding resistance to a broad spectrum of oils and solvents, to gas permeability, low temperature, ozone and weathering. Typical uses include gas meter diaphragms, rollers, printing blankets, o-rings, and many specialty molded items. 

T class elastomers contain sulfur (S atoms) in the backbone in addition to C atoms. Example polysulfide rubber (T)... 

Plastics and elastomers Degrades chlorinated polyethylene, neoprene, nitrile rubber, polysulfide, polyurethane... 

RUBBER (Synthetic). Any of a group of manufactured elastomers that approximate one or more of the properties of natural rubber. Some of these aie sodium polysulfide ( Thiokol ). polychloiopiene (neoprene), butadiene-styrene copolymers (SBR), acrylonitrilebutadiene copolymers (nitril rubber), ethvlenepropylene-diene (EPDM) rubbers, synthetic poly-isoprene ( Coral, Natsyn ), butyl rubber (copolymer of isobutylene and isoprene), polyacrylonitrile ( Hycar ). silicone (polysiloranei. epichlorohy-drin, polyurethane ( Vulkollan ). 

OTHER COMMENTS used as a solvent and extractant for resins, oils, fats, waxes, and chlorinated rubber used as a paint and varnish remover, and as a commercial solvent for degreasing metal parts useful in the synthesis of hexafluoropropylene has also been used in the synthesis of thiokol polysulfide elastomers if some branching of the polymer structure is required. 

Many hundreds of diene polymers were investigated for their suitability as elastomers. Only three of these have achieved widespread commercial acceptance butadiene-styrene copolyipers, butadiene-aciylonitrile copolymers, and poly-2-chlorobutadienes. Other essentially non-diene elastomers such as butyl rubber from isobutene, Thiokol from ethylene dihalides and polysulfides, and silicones have become important for special applications. 

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