Rubber Recycling

Historically, the chemical regeneration of rubber has been very important. By the end of the Second World War, 40% of "reclaim rubber" was used as raw material in the rubber industry, either on its own or mixed with natural or synthetic rubber.

Three reasons have led to the decline, or even disappearance, of reclaim rubber, at least in Europe and North America:

• the introduction of the radial carcass tire (replacing the conventional diagonal tire), which is much more demanding in terms of the properties of its various components;

• the very low price of raw materials;

• the use of chemicals in the manufacture of regenerated rubber that are, to say the least, a cause for concern under REACH regulations.

End-of-life rubbers (especially tires) have long been landfilled. Since 1990, various initiatives have been taken in several countries to avoid landfilling and to use end-of-life rubbers either for energy recovery or for material recovery. Without ignoring the benefits of energy recovery, the current approach is to move towards material recovery, both in tires and in industrial rubber.

In this article, after describing the rubber deposits to be recycled, the various material recycling techniques are discussed:

• incorporation as aggregates in tire and industrial rubber applications and for the preparation of thermoplastic rubbers;

• regeneration by chemical, mechanochemical and thermomechanical methods;

• pyrolysis (reinforcing fillers from pyrolysis are used in formulations). Oil from pyrolysis can also be recycled.