A representative setup for compounding polymers is presented in Figure , and this example involves a Brabender KETSE 20/40 compounder available in our laboratory. The compounding process starts by introducing the materials to combine into the top hopper of the twin screw extruder. The materials can be in the form of pellets or powder. The twin screw is heated with a precise temperature control system, so in its barrel the materials melt and mix together. They are extruded as a hot filament from the hot-end of the extruder. To cool down the filament it is passed through a cooling system, usually a water bath or a conveyor belt with pressured air, depending of the characteristics of the polymer. Once the filament is cooled down and in a solid state, it can be cut into pellets again using a pelletizer.