Styrene polysulfides

All the other reaction products appear to be chain styrene polysulfides of different molecular weights. The two oligomers I and II have been obtained from the fraction VRE approx. 0.73, and fully characterized by elemental analysis, molecular weight measurement, and various spectroscopic techniques. 

Aging of these materials in addition to changes in sulfur crystallinity may involve changes in the nature of the polysulfide fractions. For example, one styrene polysulfide has an average sulfur rank of 6.75. This is extremely high, and it can be expected to be very unstable. Tetra-sulfides and above are unstable and decompose, forming polysulfides with lower sulfur rank and elemental sulfur. Future work will explore this possibility. 

As a consequence, monomeric styrene polysulfides (from mass 168 up to m/z 328, Table 5.1) detected by DPMS, lose sulfur and yield the most... 

A similar mechanism applies to the diphenyldithianes, i.e., the cyclic styrene polysulfide dimers. However, in this case the most thermally stable compound is not the simplest cyclic dimer (m/z 272), but a thiophene derivative produced by thermal induced loss of H2S and sulfur (Scheme 5.3). As a consequence, 3,4-diphenylthiophene can be generated from head-to-tail poly(styrene tetrasulfide) units and 2,4-diphenylthiophene from tail-to-tail units. The formation of thiophene derivatives from 1,4-dithiadiene rings, by thermal loss of sulfur, is well-known in the literature. ... 

Styrene polysulfide polyamide (50-50, Poly- (diamine Plas- ... 

Hydrogen pinch, applications of, 20 764 Hydrogen polysulfides, 23 568, 639-640 Hydrogen processing, 12 404 15 217 Hydrogen-producing reactions, 13 766-767 Hydrogen product oxidation, in styrene manufacture, 23 343... 

Natural mbber comes generally from southeast Asia. Synthetic mbbers are produced from monomers obtained from the cracking and refining of petroleum (qv). The most common monomers are styrene, butadiene, isobutylene, isoprene, ethylene, propylene, and acrylonitrile. There are numerous others for specialty elastomers which include acrylics, chlorosulfonated polyethylene, chlorinated polyethylene, epichlorohydrin, ethylene—acrylic, ethylene octene mbber, ethylene—propylene mbber, fluoroelastomers, polynorbomene, polysulfides, silicone, thermoplastic elastomers, urethanes, and ethylene—vinyl acetate. 

Sealants - [ELASTOMERSSYNTHETIC - POLYISOPRENE] (Vol 9) - [SEALANTS] (Vol 21) -acrylics [ACRYLICESTERPOLYMERS - SURVEY] (Voll) -barium compds in [BARIUM COMPOUNDS] (Vol 3) -based on liquid polysulfides [POLYMERS CONTAINING SULFUR - POLYSULFIDES] (Vol 19) -defoamersin [DEFOAMERS] (Vol 7) -fiom fluorosilicones [FLUORINE COMPOUNDS,ORGANIC - POLY(FLUOROSILICONES)] (Volll) -hydrocarbon resins in [HYDROCARBON RESINS] (Vol 13) -lecithin in (LECITHIN] (Vol 15) -organolithiumcmpdsinprdnof [LITHIUM AND LITHIUM COMPOUNDS] (Vol 15) -polysulfide curing [PEROXIDES AND PEROXIDE COMPOUNDS - INORGANIC PEROXIDES] (Vol 18) -propylene oxide in mfg of [PROPYLENE OXIDE] (Vol 20) -PVB m [VINYL POLYMERS - VINYL ACETAL POLYMERS] (Vol 24) -rheological measurements [RHEOLOGICAL MEASUREMENTS] (Vol 21) -from styrenic block copolymers [ELASTOMERS SYNTHETIC - THERMOPLASTIC ELASTOMERS] (Vol 9) -use of dispersants [DISPERSANTS] (Vol 8)... 

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 ). 

Arretz, E., Lopez, F. Method for preparing organic disulfides and polysulfides from mercaptans and sulfur in the presence of heterogeneous styrene-divinylbenzene copolymer catalysts having pendant guanidine or amidine groups. 1996, WO 9721673. 

This chapter reports the study of the chemical composition of the polysulfide fraction in dicyclopentadiene and styrene modified materials, the mechanical properties of modified materials, and their use in the preparation of composite materials by the impregnation of polypropylene and glass-fiber fabrics. 

There is a strong possibility that in the examination of both these dicyclopentadiene products and those of styrene to be described, the process of extraction and examination will cause some transformation of the products because of the lability of polysulfide linkages. Thus these results should be treated with caution, but the authors believe the results give a good indication of the type of products formed. 

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. 

F Berthold, G Gellerstedt. Influence of Polysulfide on the Rate of Degradation of Six p-OH Styrene Structures at Two OH-concentrations. Holzforschung 52 490-498, 1998. 

Data have been published dealing with successful applications of HAS in stabilization of other polymers than PO elastomers, styrenic polymers, polyamides, polycarbonates, polyacetals, polyurethanes, linear polyesters, thermoplastic polyester elastomers, polyacrylates, epoxy resins, poly(phenylene oxide) or polysulfide [12]. In spite of their basicity, HAS may also be used for stabilization of PVC. This application includes less basic derivatives of piperidine and 1,4-dihydropyridine [12,13,145,146]. 

A method, using differential scanning calorimetry, has been developed to estimate quantitatively orthorhombic and monoclinic sulfur in sulfur materials. Sulfur cooled from the melt at 120°C immediately gives monoclinic sulfur which reverts to orthorhombic sulfur within 20 hr. Limonene, myrcene, alloocimene, dicyclopentadiene, cyclododeca-1,5,9-triene, cycloocta-1,3-diene, styrene, and the polymeric polysulfides, Thiokol LP-31, -32, and -33 each react with excess sulfur at 140° C to give a mixture of poly sulfides and unreacted sulfur. In some cases substantial amounts of this unreacted sulfur may be held indefinitely in a metastable condition as monoclinic sulfur or S8 liquid. Limonene, myrcene, and dicyclopentadiene are particularly effective in retarding sulfur crystallization. 

A patent (6) assigned to the Societe Nationale des Petroles d Aqui-taine covers the use of, for example, a polymer made by the interaction of epichlorohydrin, hydrogen sulfide, and alkali or alkaline earth polysulfide in aqueous solution. This polymer, HS—[CH2—CHOH—CH2— S]nH where n = 4-24, is mixed with elemental sulfur, a polyolefin (e.g. polybutene), and an olefin (e.g. styrene). This type of mixture, after heating at 140-160 °C, has been used for traffic striping and is said to be serviceable without flaking after 1 years use, despite heavy traffic. 

Examination of Polysulfide Fractions. Polysulfide fractions from the alloocimene, myrcene, limonene, styrene, and Thiokol LP-33 materials prepared at 140 °C have been fractionated by gel permeation chromatography. Other Thiokol products could not be examined because they were insoluble in all organic solvents used. In Tables VIII-XII the molecular weight and molecular formula of each fraction are given. Table... 

The first polymerization of isoprene in sealed bottles was reported in 1884 by Tilden. Methyl rubber was thermally polymerized at 70°C — the reaction required 3 to 6 months, giving poor quality products. In 1926 BASF developed sodium-initiated polymerization of butadiene known as Buna (for BUtadiene -I- Natrium). The first successful, general purpose rubbers were copolymers of butadiene with either styrene, Buna-S, or acrylonitrile, Buna-N [Tschunkur and Bock, 1933 Komad and Tschunkur, 1934]. Poly(2-chlorobutadiene), chloroprene [Carothers et ah, 1931], was introduced in 1931 by DuPont. Elastomeric polysulfides [Patrick, 1932] were... 

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. 

OTHER POLYMERS SHOWING THESE SPECIAL PROPERTIES Solvent resistance polysulfide rubbers second order transition temperature styrene-butadiene rubbers weather and ozone resistance jxjlychloroprene rubbers. 

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