Neopren

What it is

Neoprene exhibits good chemical stability and maintains flexibility over a wide temperature range. Chloroprene rubber is far more weather resistant than natural rubber, and its resistance to oil, petrol and chemicals is also good. The monomer, chloroprene, is a colorless volatile liquid. Its IUPAC name is 2-chlorobuta-1,3-diene and its formula is C₄H₅Cl. It differs from isoprene, the monomer of natural rubber, in that a methyl group is exchanged with a chlorine atom.

Production

Chloroprene is produced in three steps from 1,3-butadiene: chlorination, isomerization of part of the product stream, and dehydrochlorination of 3,4-dichlorobut-1-ene. Until the 1960s, chloroprene production was dominated by the acetylene process, which has since been replaced by the chlorination of 1,3-butadiene. Chloroprene rubber in finished products is vulcanised using zinc oxide. Vulcanisation forms cross links between the rubber chain molecules that improve the elasticity of the rubber, remove its adhesiveness and make the rubber dimensionally stable. Neoprene foam is produced in either closed-cell or open-cell form. The closed-cell form is waterproof, less compressible and more expensive. Foam is made by foaming the rubber with nitrogen gas, and the tiny enclosed gas bubbles can also serve as insulation.

Uses

Neoprene is sold either as solid rubber or in latex form. It is well suited to demanding applications such as gaskets, hoses and corrosion-resistant coatings. Foamed neoprene is commonly used to make fly fishing waders, wetsuits and drysuits as thermal insulation. The insulation of neoprene foam depends mainly on bubbles of gas enclosed within the material, which reduce its ability to conduct heat. Neoprene is also latex-free, which makes it a safer option for people with latex allergies. Neoprene's burn point is around 260 °C (500 °F).

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