3. Fundamentals of reactive extrusion

3.1 Chemical reactions

As already mentioned, chemistry in extruder takes place under thermomechanical conditions close to those of a conventional extrusion process, which are very different from those usually encountered in reactors. For example, the reaction medium is unusual as it is essentially composed of molten polymers in the absence of solvents. Its viscosity and temperature are often very high. The absence of solvents means that the reactants involved may be immiscible. As a result, the reaction may no longer take place over the entire reaction volume, but mainly at the interfaces. In addition, the reaction time is very short, since it is dictated by the average residence time in the extruder, which is often between a few seconds and a few minutes.

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