Dissolving neoprene

Neoprene solvent solutions are prepared by dissolving neoprene in standard rubber solvents. These solutions can be formulated in a range of viscosities suitable for application by brush, spray, or roller. Major areas of application include coatings for storage tanks, industrial equipment, and chemical processing eqmpment. These coatings protect the vessels from corrosion by acids, oils, alkalies, and most hydrocarbons. 

Once the solubility parameter and hydrogen bonding index of the blend has been determined, the blend can be positioned on the chart shown in Fig. 6. Solvents or blends which fall within the kidney shaped area will yield smooth, free-flowing solutions with all solvent grade types except Neoprene AH. Those which fall outside the kidney shape will not dissolve Neoprene. If a particular solvent blend falls in the shady area it may or may not be suitable depending on the amount of true solvent (e.g., toluene) in the blend. 

Spraying. A low Mooney, low nerve Neoprene is preferred. Milling is required for the best spray characteristics. The viscosity should be below 250 cps. The solvent blend should contain predominantly fast-evaporating solvents which individually could not dissolve Neoprene. 

Extreme caution must be taken to prevent the possibility of fire when using flammable removers. Extra care must be taken when stripping on location to secure the area of ignition sources. When used on lacquer finishes, the dissolved finish and remover combined are extremely flammable. Natural mbber, neoprene, or other gloves suitable for use with the remover formula must be worn. The effect of skin contact with the remover is limited because there is immediate irritation and discomfort. Canister respirators are available for most petroleum and oxygenate remover solvents. Symptoms of long-term overexposure should be compared to symptoms of the major ingredients in the formula. 

Once the <5 and y values of a given blend are determined, the values are positioned in the graphic chart given in Fig. 37 [77]. The blends that fall within the kidney-shaped area yield good solutions with all solvent grade polychloroprene types, except for Neoprene AH, and those which fall outside that area will not dissolve the polychloroprene. The solvent blends which fall within the shadow area, may or may not dissolve the polychloroprene depending on the amount of toluene. 

Vehicle LPG storage tanks are cylindrical with rounded ends and are capable of holding fuel at pressures of 240 to 250 psig. The tanks are much stronger than those used to hold conventional liquid fuels, but less sophisticated than CNG storage tanks. Carbon steel or aluminum can be used for tank construction. Because propane can dissolve plasticizers used in elastomer production, only propane-resistant elastomers such as neoprene, nitrile, or Teflon should be used. Except for the need for a gas-tight connection, LPG can be dispensed in the same manner as gasoline or diesel fuel. To ensure that adequate vapor space is available for gas expansion, automatic limiters are incorporated to maintain an 80% maximum fill rate. 

To 500 ml. of absolute methanol (Note 1) in a 1-1. electrolytic (tall form) beaker is added 1.1 g. (0.05 g. atom) of clean sodium metal. After solution of the sodium, 216 g. (1.0 mole) of methyl hydrogen sebacate (Note 2) is dissolved in the sodium methoxide solution. A magnetic stirring bar is placed in the beaker which is then fitted with a large neoprene stopper (Note 3) holding a platinum sheet anode, 12 cm.2 in area and two platinum sheet cathodes, approximately 5.3 cm.2 in area, spaced equidistantly on either side of the anode at a distance of approximately 1.5 cm. (Note 4). The stopper is also provided with a stoppered entry tube and an efficient reflux condenser (Note 5). 

Polychloroprene (Neoprene W or AC Soft, E. I. duPont de Nemours and Co.) was dissolved in toluene, precipitated in methanol, and dried in a vacuum oven at room temperature. This procedure was repeated three times. The polymer was used immediately after the last precipitation. Neoprene W and Neoprene AC Soft have Mns of 180,000 and 230,000, respectively, and allylic chloride contents of 1.45 and 0.77 mol%, respectively. The Mns were determined by osmometry, and mol% allylic chloride are based on an IR measurement of the 1,2-addition-product band of polychloroprene at 921 cm"1 (5). PTHF used for DTA and stress-strain measurements had TvTn = 95,000. 

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. 

The metering valve in an MDI is the critical component in the design of an effective delivery system. The main function of the metering valve is to reproducibly deliver a portion of the liquid phase of the formulation in which the medication is either dissolved or dispersed. The valve also forms the seal atop the canister to prevent loss of the pressurized contents. The valves generally comprise at least seven components that are constructed from a variety of inert materials. Typical materials of construction are acetal or polyester for the valve body, stainless steel or acetal for the valve stem, generally anodized aluminum for the ferrule, and butyl, nitrile, or neoprene for the elastomers used in the seals and gaskets [43],... 

Neoprene is less affected by gasoline and oil and is more elastic than natural rubber. It resists abrasion well and is not swollen or dissolved by hydrocarbons. It is widely used to make hoses for oil and gasoline, electrical insulation, and automobile and refrigerator parts. 

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