Neoprene rubber solvent properties

Hypalon is a close match to neoprene in most properties, but it is superior in resistance to acids, solvent, ozone and oxidation, and has decidedly better color stability. This rubber can be used instead of polychloroprene or plasticized polyvinyl chloride in many applications. 

Neoprene. Neoprene is an elastomer with mechanical properties very similar to natural rubber. It is manufactured by Du Pont and has a safe working temperature range of -15°C to 80°C. It is resistant to oils, to organic solvents, to some caustic solutions and to salts. It is not suitable for hydrogen peroxide or sulphur trioxide. Neoprene has low permeability to gases and is good for high vacuum and static vacuum systems. 

Neoprene is also available in a variety of forms. In addition to a neoprene latex that is similar to natural rubber latex, neoprene is produced in a "fluid" form as either a compounded latex dispersion or a solvent solution. Once these materials have solidified or cured, they have the same physical and chemical properties as the solid or cellular forms. 

Polysulfide rubbers posses outstanding resistance to solvents. They exhibit excellent resistance to oils, gasoline, and aliphatic and aromatic hydrocarbon solvents, very good water resistance, good alkali resistance, and fair acid resistance. FA polysulfide rubbers are somewhat more resistant to solvents than ST rubbers. Compounding of FA polymers with NBR will provide high resistance to aromatic solvents and improve the physical properties of the blend. For high resistance to esters and ketones, neoprene W is compoimded with FA polysulfide rubber to produce improved physical properties. 

The fluorinated rubbers are exceptionally good for high-temperature service, but they are below silicones in this respect. They resist most of the lubricants, fuels, and hydraulic fluids encountered in aircraft a wide variety of chemicals, especially the corrosive variety and also most chlorinated solvents. They have good physical properties, somewhere near those of styrene butadiene rubber (SBR) at the higher hardness levels. FKM is valnable in automotive use for its extreme heat and oil resistance and is on a much higher level in this respect than the acrylic elastomers. It has weathering properties snperior to those of neoprene. However, fluoroelastomers are relatively expensive. 

Polychloroprene resembled vulcanized rubber in ite physical properties but was superior in its resistance to ozone, ordinary oxidation and to most organic solvents. Commercial sale of polychloroprene, under the generic name "neoprene" and trademark "Duprene", began in June, 1982, about two years after its discovery. 

The most typical adhesive solvents are those based on elastomers, compounds characterized by the fact that they have a strong natural adhesiveness, especially in respect of themselves (the phenomenon of self-adhesion, the instantaneous adhesion of two films of glue after almost total evaporation of the solvent, is the basis for the composition of the contact glues especially neoprene-based (Fletcher 1971)). The basic chemical composition of neoprene synthetic rubber is polychloroprene (O Fig. 14.6). The polymer structure can be modified by copolymerizing chloroprene with, for example, 2,3-dichloro-1,3-butadiene to yield a family of materials with a broad range of chemical and physical properties. 

Polysulhdes often are blended with other elastomers such as nitrile rubber, NBR, or neoprene, CR, for improved physical properties and factory processing. Traditionally, Thiokol FA is blended with neoprene for improved strength and processing for rollers, at some sacrihce in solvent resistance. Table 11.9 has information on Thiokol FA blends. If minimal loss in chemical resistance is indicated, then a blend with a high ACN nitrile is employed. A cure system that is compatible with both rubbers needs to be used in all cases. The zinc peroxide-cure system is NBR specihc, hence it is important that the recommended one be used or others be tested since many NBRs do not cure with zinc peroxide. Best results are obtained with blends if separate masterbatches are made with the individual polymers, which are then blended in the... 

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