Solubility neoprene

Because the viscosity of neoprene latex at a given soHds content is less than that of natural mbber latex, thickeners are generally needed with the former. MethylceUulose and the water-soluble salts of poly(acryhc acid) are the two most commonly used thickeners. Natural and synthetic gums are also used. 

Polychloroprene polymers also vary in the degree of branching in the polymer. Polychloroprenes with little or no branching are called sol polymers, whereas those with considerable branching are referred to as gel polymers. Sol polymers are soluble in aromatic solvents. All of the solvent-grade polychloroprene polymers (except Neoprene AG) are sol polymers. The gel content in the polychloroprene affects the cohesive strength, resilience, elongation, open tack time, resistance to permanent set, and oil swell. 

Chloroprene (2-chloro 1,3-butadiene), a conjugated non-hydrocarbon diolefm, is a liquid that boils at 59.2°C and while only slightly soluble in water it is soluble in alcohol. The main use of chloroprene is to polymerize it to neoprene rubber. 

The incorporation of polar groups in unvulcanized polymers reduces their solubility in benzene. Thus the copolymer of acrylonitrile and butadiene (NBR), polychlorobutadiene (Neoprene), and fluorinated EP (the copolymer of ethylene and propylene) are less soluble in benzene and lubricating oils than the previously cited elastomers. Likewise, silicones and phosphazene elastomers, as well as elastomeric polyfluorocarbons, are insoluble in many oils and aromatic hydrocarbons because of their extremely low solubility parameters (silicons 7-8 H polytetrafluoroethylene 6.2 benzene 9.2 toluene 8.9 pine oil P.6). 

The precautions to be taken will vary with the properties of the chemical. For example, dimethylmercury is volatile (bp 92°C), oil soluble, and flammable. Hence it should be handled well back in a hood, its container should be open as little as possible, gloves of oil-resistant material (neoprene or nitrile rubber) should be worn, the user s front should be protected by a rubber apron if more than a gram or so is used, and no open flame should be nearby. With thalidomide, a solid of negligible volatility and low oil-solubility, prompt stoppering of an opened container would be less important, thin... 

Solubility and Composition. The copolymers are quite soluble and continue to be soluble if antioxidant is added otherwise some gelatin occurs. The usual solvents for neoprene and PTHF (CH2C12, CHC13, CC14, toluene, THF, etc.) are also solvents for the graft copolymers. But there are some unexpected features about the solubility. Benzene dissolves both the backbone and the branch quite readily. Yet at least one graft copolymer, which dissolved readily and completely in CH2C12 and ethyl acetate, swelled but did not dissolve in benzene. Also some of the copolymers were not completely soluble in toluene and THF. Still all the neoprene-g-PTHF copolymers were 100% soluble in ethyl acetate, a nonsolvent for neoprene. As shown in Table III, the ethyl-acetate extracts had in each case the same composition by H NMR as the crude products. Thus it appears that the backbone was pulled into its nonsolvent by the PTHF branches. This means that no unreacted backbone remained. 

Molecular-Weight Distribution. The solid line in Figure 1 shows a typical gel-permeation-chromatogram trace for an unfractionated neoprene-g-PTHF (Polymer 1, Table I) that was soluble in THF. The... 

Summary. Solubility, H NMR, DTA, and GPC all support the conclusion that pure graft copolymer is obtained by the present method of synthesis. The only purification necessary is removal of the silver salts. Properties of the neoprene-g-PTHF copolymers depend on composition and branch length and generally lie between those of the backbone and branch. 

This substance has extensive lipid solubility and is absorbed immediately by the skin. Additionally, DMM is able to penetrate many materials including plastic and rubber compounds such as latex, polyvinyl chloride, and neoprene in a matter of seconds. In permeability tests, a Silver Shield glove of a flexible, plastic-laminate, offered skin protection from DMM for 4h. This chemically resistant glove, when worn under an outer glove that is resistant to abrasion and tears, may provide limited protection for direct handling of DMM. 

Another possible explanation may be Increasing solubility of DI water In these Neoprene formulations, due, of course, to the additives. Other studies carried out at 5, 25 and 5O C over 24-40 day terms have shown that fresh water continues to be absorbed by Neoprene WRT without reaching equilibrium (vide Infra). Because permeability Is dependent on solubility, a continuing Increase In the latter will affect the former similarly. 

In the Neoprene G tests summarized In Figure 1 and Table I the outer (dry) faces of the permeated rubber samples were washed with DI water to determine If soluble salts were present. The conductivity values listed In Table I show only a very slight difference, t lch Is probably of little Import. The Internal water permeant was, however, changed by the long term aging. 

Figure 3 Illustrates the change of solubility of water in WRT Neoprene with temperature. The solubilities of both deionized and 3.5% salt water were measured at 5, 25 and 50°C. The figure shows that DI water is more soluble than salt water in WRT Neoprene and that increasing temperature Increases solubility. The solubility of DI water at 50°C does not approach equilibrium even after 25 days. From these data a total weight gain of 300% was predicted.

Several elastomers were evaluated for permeability to salt and deionized water at several temperatures. A WRT Neoprene (Burke Rubber Co. Type 5109) was tested at 23, 40 and 70°C using both salt water (3.5%) and DI water as permeants. The results for salt water are listed In Table III and for DI water In Table IV. Salt water permeability Increased 24 times with a 47°C temperature rise while the DI water Increase was 33 times. The difference may be due to the much greater solubility of DI water relative to salt water. 

Temperature effects are important, not only in high temperature applications, but also during accelerated aging of a material for laboratory study and subsequent evaluation of in-service life-time. Solubility of water In Neoprene Increases greatly with temperature as does permeation rate. The relative permeation rates of 3.5% saltwater and deionized water were shown to depend on elastomer composition. 

Beilstein Handbook Reference) AI3-00393 Bis(n-butyl) sebacate BRN 1798308 Butyl sebacate Decanedioic acid, dibutyl ester Dl-n-butyl sebacate Dibutyl 1,8-octanedicarboxylate Dibu l decanedioate Dibutyl sebacate Oibutyi sebacinate Dibutylester kyseliny sebakove EINECS 203-672-5 FEMA No. 2373 HSDB 309 Kodaflex DBS Monoplex DBS NSC 3893 Plasthall DBS Polycizer DBS PX 404 Reomol DBS Sebacic acid, dibutyl ester Staflex DBS Uniflex DBS. Monomeric plasticizer for plastics and rubber (cellulosics, PVC food wraps, nitrite and neoprene rubbers). Used as an excipient in various pharmaceutical coaling formulations. Viscous liquid mp = -10° bp = 344.5°, bp3 = 180° d = 0.9405 insoluble in H2O, soluble in Et20, CQ4. Hall C.P. Union Camp. 

Diethylamine Miscible Dieth ether Miscible bis-(2.ethylhexyl)amine 0.7 Diethyl sulfide MlKible Di-isobutyl carbinol Miscible Di-isobutylene 3.3 <0.6% DMSO soluble in di-isobutylei>e) Disopropyl ether 11 Dimethyl ether 4.4 Dimethyl formamide Miscible Morpholine Naphthalene Neoprene Nitrobenzene Oleic acid Ouricuri wax Oxalic add Palmitic acid Paraffin Paraformaldehyde Miscible 40 Insol. Miscible Misdble 38 100 Insoluble Insoluble Miscible Inso 1 Slightly soluble... 

Sansone et alP have calculated the permeability coefficients of benzene vapours in air from the measured values of solubility and diffusivity for NR/neoprene blend membrane. 

The situation did not change until 1942, soon after the start of World War II. At that time, a critical shortage of natural rubber developed because it was allocated chiefly for the war effort. Neoprene was chosen as a replacement for natural rubber in adhesives because it was the only other synthetic rubber available. Animal glue and other water-soluble materials available at the time were unsatisfactory because of their slow drying rates, poor adhesion to many surfaces, inflexible films, and rusting of metals. The two Neoprene polymers available at the time were Neoprene GN, a general purpose type, and Neoprene CG, a fast-crystallizing type. Both are copolymers of chloroprene and sulfur which contain a thiuram disulfide modifier. 

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