4. Thermoplastic rubbers

These new types of rubber appeared on the market in the 1970s and are classified into four main families:

• styrene-based block copolymers;

• polyurethanes ;

• PP (polypropylene)-based physical blends;

• copolyesters.

Here again, there are numerous grades in each family. Their main characteristic, due to the presence of elastic and thermoplastic phases in their molecular structure, is that at moderate temperatures they behave like vulcanized rubbers, but can be processed like plastics at high temperatures.

Table 8 shows the main properties and grades of these rubbers. In general, the temperature limit is set by the requirements for...