neoprene

neoprene: see rubber.

Any of a class of elastomers (rubberlike synthetic organic compounds of high molecular weight) made by polymerization of the monomer 2-chloro-1,3-butadiene and vulcanized (cross-linked, like rubber), by sulfur, metallic oxides, or other agents. These synthetic rubbers, discovered in 1931 (see W.H. Carothers), are generally too expensive to use in making tires, but their resistance to chemicals and oxidation (see oxidation-reduction) makes them valuable in specialized applications, including shoe soles, hoses, adhesives, gaskets, seals, and foamed articles.

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Neoprene or polychloroprene is a family of synthetic rubbers that are produced by polymerization of chloroprene. It is used in a wide variety of applications, such as in wetsuits, laptop sleeves, orthopedic braces (wrist, knee, etc.), electrical insulation, and car fan belts. Neoprene is the DuPont Performance Elastomers trade name.

History

Neoprene was invented by DuPont scientists on 17^th April 1930 after Dr. Elmer K. Bolton of DuPont laboratories attended a lecture by Fr. Julius Arthur Nieuwland, a professor of chemistry at the University of Notre Dame. Fr. Nieuwland's research was focused on acetylene chemistry and during the course of his work he produced divinyl acetylene, a jelly which firms into an elastic compound similar to rubber when passed over sulfur dichloride. After DuPont purchased the patent rights from the university, Wallace Carothers of DuPont took over commercial development of Nieuwland's discovery in collaboration with Nieuwland himself. DuPont focused on monovinyl acetylene and reacted the substance with hydrogen chloride gas, manufacturing chloroprene.

Neoprene (originally called duprene) was the first mass-produced synthetic rubber compound.

Applications

Its chemical inertness makes it well suited for industrial applications such as gaskets, hoses, and corrosion-resistant coatings. It can be used as a base for adhesives, noise isolation in power transformer installations, and as padding in external metal cases to protect the contents while allowing a snug fit. Neoprene weather stripping is commonly used in fire doors as its fire resistance is higher than exclusively hydrocarbon based rubbers, also resulting in its appearance in combat related attire such as gloves and face masks. Neoprene is also used as a contrast in some jewelry designs. Its springy consistency makes it notoriously difficult to fold when in sheet form.

Neoprene is commonly used as a material for fly fishing waders, as it provides excellent insulation against cold. Neoprene waders are usually about 5 mm thick, and in the medium price range as compared to cheaper materials such as nylon and rubber. However, neoprene is less expensive than breathable fabrics.

For diving and exposure protection applications, the air spaces in the neoprene are filled with nitrogen for its insulation value. This also makes the material quite buoyant, and the diver must compensate for this by wearing weights. Thick wet suits made at the extreme end of their cold water protection are usually made of 7 mm thick neoprene. It should be noted that since neoprene contains air spaces, the material compresses under water pressure, getting thinner at greater depths. So a 7 mm neoprene wet suit offers much less exposure protection under one hundred feet of water than at the surface. A recent advance in neoprene for wet suits is the "super-flex" variety which combines spandex into the neoprene for a greater flexibility.

Recently, neoprene has become a favorite material for lifestyle and other home accessories including laptop sleeves, iPod holders, remote controls, etc.

Also in recent years, Jug, an aftermarket inline skate liner manufacturer, has incorporated neoprene into the construction of some of their more popular product-lines, citing that neoprene adds reinforcement (ankle support) and guards against abrasions like few materials do. As a simple matter of durability and product lifespan, liners constructed with neoprene additives are typically more expensive than those which are not.

Musical instrument maker Yamaha has begun replacing corks not used for sealing (such as sealing the joints of a clarinet or oboe) with neoprene.

Neoprene is also used for drum practice pads.

It is also commonly in its Neoprene spandex mixture used in wheelchair positioning harnesses.

Precautions

Although neoprene itself is not a skin contact sensitizer, certain neoprene adhesives contain 4% rosin (CAS No. 8050-09-7, previously known as "colophony"), which is a skin contact sensitizer under the European Union Dangerous Preparations Directive 1999/45/EC. Some people are allergic to neoprene while others can get dermatitis from thiourea, a compound used to vulcanize rubber into neoprene which can be left over after the manufacturing process.

Lead-containing compounds, such as litharge (lead(II) oxide), are used as compounding agents to prepare finished products made of neoprene, and these can have a toxic effect on human blood, kidneys, and reproductive systems.

References