3. Choice of elastomers

The preceding paragraphs have shown the importance of the nature of the base elastomer, and the various ingredients used in compound formulation. Moreover, for a given type of elastomer, whether NR or SR, there are many different grades (different presentation or modification of the elementary molecule for the same type of elastomer). It would be tedious to go into the details of these rubbers, but we can simply mention the following grades by way of example.

• For NR :

  • smoked leaves in various presentations;

  • white and brown pancakes ;

  • air-dried leaves ;

  • specified rubbers (viscosity, cleanliness) ;

  • deproteinized rubber ;

  • NR grafted...