On the stability of reactive extrusion

Interest in reactive extrusion has grown considerably during the last decad e. The instabilities that may occur during polymerization in extruders can pose severe limitations on the process and on its scalability. They manifes t themselves as severe fluctuations in throughput and product quality or as dual steady states, one at low conversion and one at high conversion. Thes e instabilities may be of thermal, hydrodynamic, or chemical nature. In thi s paper the possible sources of instabilities are identified in a qualitati ve way and some possibilities to prevent them are given. Because some of th e instabilities are dependent on the scale of the equipment, experiment des ign is important when a reactive extrusion process has to be developed on l aboratory equipment and successively scaled up to larger machines.