Extrusion Processes

A method of forming a functionalized polymer, the method comprising:

• introducing a polymer and a coupling agent to an extruder at a feed throat of the extruder;
• and
• extruding the polymer and the coupling agent through at least a portion of the extruder via a plurality of intermeshing screws disposed within the extruder to form the functionalized polymer,
• wherein at least one screw of the plurality of intermeshing screws has a first mixing zone having a total length of about 4 L/D to about 6 L/D, a second mixing zone having a total length of 2.5 L/D to 3.5 L/D, and a third mixing zone having a total length of about 2.5 L/D to about 4.5 L/D,
• wherein the first mixing zone is a mixing zone closest to the feed throat of the extruder, the second mixing zone is disposed downstream of the first mixing zone relative to the feed throat, and the third mixing zone is disposed downstream of the second mixing zone relative to the feed throat.