What is neoprene?


Put simply, neoprene is a type of foamed synthetic rubber. In technical terms neoprene is a type of polymer (a large molecule composed of repeating structural units) known as polychloroprene that is produced by the polymerization (chemical reaction) of chloroprene (an organic compound of colourless liquid with the formula CH2=CCl-CH=CH2). Chloroprene is the monomer in this process (a molecule that binds chemically to other molecules to form a polymer).

In other words, neoprene is made through a chemical reaction using chloroprene. It is chloroprene that binds all the molecules of this reaction together, leaving us with polychloroprene chips. These chips are melted and mixed together with foaming agents and carbon pigments, and then baked in an oven to make it expand. The end result is then sliced like bread, leaving smooth neoprene sheets. Nylon fabric can then be laminated to the neoprene to give it strength.

 
Neoprene: a brief history

During the 1920s the increasing demand for natural rubber led to higher and higher prices, sparking a search for an equivalent synthetic rubber. It was during 1930 that a chemist in DuPont's fundamental research group created neoprene. Experiments by a number of people in the early 1950s helped make neoprene the number one material for wetsuits (although other materials were used, especially in Europe). But at that time neoprene was weak, tore easily and was hard to put on. The lamination of fabric to neoprene in the 1960s resolved this problem and led to the modern wetsuits we use today.

The 1960s also saw a new type of neoprene pioneered by Japan's Yamamoto Corporation. Instead of traditional oil-based neoprene, Yamamoto developed special technology to convert the calcium carbonate from limestone into chloroprene rubber chips, producing limestone neoprene (the neoprene we at Seventhwave use today).

 

Limestone neoprene

Limestone neoprene has a high micro-cell structure. These are independent closed cells (bubbles basically) within the neoprene that are packed together at an extremely high density. Oil-based neoprene has a cell penetration of 60-70%, whereas limestone neoprene has a 94% cell penetration. What this means in simple terms is that limestone neoprene has a lot more air bubbles inside the rubber than other brands (over 30% to be exact), and is way less dense than oil-based neoprene.

Because of this micro-cell structure, limestone neoprene provides several serious distinct advantages to the functionality of wetsuits compared to the traditional oil-based neoprene:
 

    It is more impermeable
    It is lighter in weight
    It is warmer
    It is more durable
    It is stretchy

 
How is limestone neoprene made?

The first stage of production is to make the polychloroprene rubber chips. To do this, extracted limestone is fed into a furnace and heated at a temperature around one-tenth of that used for refining petroleum. The source of the heat is from burning used tires and hydroelectric power sourced from several local dams (any waste heat is then reused to power a local eel nursery). From the furnace, components are reacted with other chemicals to make the acetylene gas needed for the polychloroprene rubber chips.

The polychloroprene rubber chips are then melted and mixed together with foaming agents and black carbon pigments, and then baked in an oven to make it expand. Once this sponge block has cured the next process is to slice it up into sheets. This is like slicing a loaf of bread, except it is slit horizontally and to the desired neoprene thickness. Finally, the soft sheets are laminated with high stretch nylon or polyester jersey knit to give them strength.

 
Can neoprene be green or eco-friendly?

We would have to say that any neoprene is not totally environmentally friendly to our planet and environment. However, there are two very distinct types of neoprene available, oil-based neoprene and limestone-based neoprene, and they have very different characteristics. So really the question should be: 'Can one neoprene be more green or eco-friendly than the other?'

What contributes to limestone neoprene being more 'green' depends on its use of more sustainable and less toxic resources during production, and the longer its useful life span is (ie the longer it will stay out of landfill). Limestone neoprene is arguably more eco-friendly than petro-chemical neoprene, but there's a long way to go before a wetsuit and its production can be truly green. We are working on it!