When exiting a reactor after a polymerization reaction, many polymers still contain undesired low-molecular weight components.  These component may make the product unusable for further processing (for example, a polymer solution cannot directly be used for plastics processing), may be toxic, may cause bad sensory properties such as an unpleasant smell or worsen the properties of the polymer. It may also be desirable to recycle monomers and solvents to the process. Plastic recycling can also involve removal of water and volatile degradation products.