Styrene-butadiene rubber , soluble

The hydrogenation in a liquid-liquid system with ionic liquids as the catalyst phase was also applied to the hydrogenation of polymers. The first studies were presented by the group of Rosso et al. [91], who investigated the rhodium-catalyzed hydrogenation of polybutadiene (PBD), nitrile-butadiene rubber (NBR) and styrene-butadiene rubber (SBR) in a [BMIM][BF4]/toluene and a [BMIM][BF4]/tolu-ene/water system. The activity of the catalyst followed the trend PBD>NBR> SBR, which is the same order as the solubility of the polymers in the ionic liquid. The values in percentage total hydrogenation after 4 h reaction time were 94% for PBD and 43% for NBR, and after a reaction time of 3 h was 19% for SBR. 

BUTADIENE. [CAS 106-90-0]. CHrCH C CH3, 1,3-butadiene (methyl-allene), formula weight 54.09. bp —4.41cC, sp gr 0.6272, insoluble in H2 O. soluble in alcohol and edier in all proportions, Butadiene is a very reactive compound, arising from its conjugated double-bond structure. Most butadiene production goes into die manufacture of polymers, notably SBR (styrene-butadiene rubber) and ABS (acryloiiitrile-buladiene-slyrene) plastics. Several organic syntheses, such as Diels-Alder reaction, commence with the double-bond system provided by this compound. 

Iwai, Y. Miyamoto, S. Nakano, K. Arai, Y., "Measurement and Prediction of Solubilities of Ethylbenzene Vapor in Styrene Butadiene Rubbers," J. Chem. Eng. Japan, 23, 508... 

The free-radical kinetics described in Chapter 6 hold for homogeneous systems. They will prevail in well-stirred bulk or solution polymerizations or in suspension polymerizations if the polymer is soluble in its monomer. Polystyrene suspension polymerization is an important commercial example of this reaction type. Suspension polymerizations of vinyl ehloride and of acrylonitrile are described by somewhat different kinetic schemes because the polymers precipitate in these cases. Emulsion polymerizations aie controlled by still different reaetion parameters because the growing macroradicals are isolated in small volume elements and because the free radieals which initiate the polymerization process are generated in the aqueous phase. The emulsion process is now used to make large tonnages of styrene-butadiene rubber (SBR), latex paints and adhesives, PVC paste polymers, and other produets. 

Iwai, Y. et ah. Measurement and prediction of solubilities of ethylbenzene vapor in styrene-butadiene rubbers, J. Chem. Eng. Jpn., 23, 508, 1990. 

Xanthates were also used for microencapsulation of pesticides the pesticide and a soluble xanthate were blended in aqueous solution followed by acidification and the addition of a coupling agent to form a matrix.2218-2227 Particles of nitrile-butadiene rubber (NBR) and styrene-butadiene rubber (SBR) were also encapsulated by starch xanthates.2228... 

If the feed is preconditioned properly, the UF flux is often quite stable. One thousand hours of continuous operation between cleanings is common. When flux decay does occur, detergent washing is usually sufficient to restore flux. In some cases, polymer solvents may be required. Proper selection of a solvent resistant membrane and/or solvents which will dissolve the latex but not affect the membrane is crucial. For PVC latex, the solvents of choice are methyl isobutyl ketone (MIBK) and methyl ethyl ketone (MEK). Styrene butadiene rubber will swell in MIBK, MEK or toluene. Polyvinyl acetate will dissolve in the low MW alcohols such as propyl alcohol. Generally, the membranes are first washed with water, then detergent, followed by another water flush. The system is then drained of all water since it will affect polymer solubility in MEK. Finally, a solvent rinse is employed. If the module is tubular, sponge balls will enhance cleaning. 

WUH Wu, J., Pan, Q., and Rempel, G.L., Solubility of ethylene in toluene and toluene/styrene-butadiene rubber solutions, J. Appl. Polym. Sci., 96, 645, 2005. 

Nitrile polymers are vulcanized in essentially the same manner as styrene butadiene rubber (SBR) and natural rubber. The same ingredients are used, although not necessarily in the same amounts. Sulfur is less soluble in nitrile rubber than in SBR or natural rubber, and smaller amounts are used. A corresponding increase in accelerator is required. Sulfur/accelerator, sulfur donor, and peroxide cures are chosen depending on the ultimate processing methods and applications. 

The chemical properties of the block copolymers are similar to those of unvulcanized styrene-butadiene rubber. Thus the block copolymers are soluble in a range of solvents, including chlorinated and aromatic hydrocarbons, esters and ketones. 

Emulsion Polymerized SBR The bulk of styrene-butadiene rubber is produced by free radically initiated emulsion polymerization. Before 1950 polymerization was usually carried out at about 50 C using a water-soluble initiator such as potassium persulphate with the average molecular weight being controlled largely by chain transfer agents such as t-dodecyl mercaptan. Conversion of monomer to polymer was taken to about 72% at which point hydroquinone was added as a polymerization stopper. Because of the non-linear nature of the polymer such rubbers were inferior to natural rubber. For reasons which will shortly become... 

Pillai and co-workers demonstrated an effective way of using a compatibiliser to improve the PMMA and styrene-butadiene rubber (SBR) system. They created thin films of polymers of poor solubility using silane compatibiliser additives [40] in that work organosilanes containing Cg, Cio, Q2 and Cig aliphatic chains were used in the PMMA/SBR blends. It was found that the compatibiliser effect of organosilane was largely dependent upon the number of carbon atoms in the aliphatic chain. The reasons for that phenomenon was primarily due to the steric effect, as silane-type compounds with different aliphatic chain lengths develop interfacial layers of different thicknesses [40]. 

Synthetic Rubber. Many different types of synthetic rubber are suitable raw materials for adhesives and sealing compounds. Particularly significant are polychlo-roprene rubber, styrene-butadiene rubber (SBR), nitrile rubber, and polyisobutylene. Unless these rubbers are available as directly soluble types, they have to be degraded by mastication on rolls or in kneaders and solubilized before dissolution. 

Both the gel and toluene soluble fractions are reserved for determination of unsaturation by the iodine monochloride method. To determine unsaturation in styrene-butadiene rubbers with good accuracy using the iodine monochloride procedure, it was found necessary to contact the sample with chloroform for 15 hours before reaction with iodine monochloride. Even with a 30 hour reaction period, a constant iodine-value is obtained only when a five-fold excess of iodine monochloride reagent is used. 

Crompton and Reid [113] used these procedures to study the distribution of rubber added in several laboratory preparations of high impact polystyrene containing 6 wt% of a styrene-butadiene rubber and 94% styrene, i.e., theoretical 4.1% butadiene. The results in Table 3.12 show the way in which the added unsaturation of 4.1 % butadiene distributes between the gel and soluble fractions the butadiene content of the separated gel remains fairly constant, in the 20-25% region, regardless of the quantity of gel present in the sample. As the gel content... 

These admixtures are used to increase the bond strength in repair applications, to decrease shrinkage, increase tensile strength, etc. The polymers used include latexes, redispersible polymer powders, water-soluble polymers, liquid resins, and monomers. In practieal applications, styrene butadiene rubber, polyacrylic ester and polyvinylidene chloride-vinyl chloride, methylcellulose, etc., have been used. 

Impact modifiers are usually prepared by grafting methylmetacrylate and styrene on a styrene-butadiene rubber in an emulsion process (29,30). The preparation and properties of these polymers has been reviewed (31). Impact efficiency is achieved by controlling the rubber substrate particle size between 1000 and 3000 A in a narrow distribution range. The solubility-incompability balance determines the performance of impact modifiers. Typical opaque compound impact modifiers show high efficiency. High-efficiency impact modifiers are used in PVC conduit, injection molding components and calendered opaque films and sheets. Various types of impact modifiers are available (32,33). 

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