Extruder Temperature
Vol. 35 #1, Winter 2010
Remember that for maleic anhydride containing tie resins, you should get them up to 210 deg C minimum in the extruder even if you want to run them cooler in the die when coextruding with EVOH. If you get them up to 210 deg C by the metering zone of the screw, this will help to ensure that most of the hydrous form of maleic is reverted to the anhydride form by the time the material gets into the adapter. In pellet form, MAh containing polymers absorb moisture from the ambient conditions, and some of the MAh is changed to maleic acid. If you extrude the polymer at very cool temperatures, you will not open the rings, drive off the moisture, and convert it back to maleic anhydride. If you are having coextrusion adhesion problems to EVOH (or Nylon), checking that your extrusion temperature profile through the extruder is proper, is one of the first things to do.
- Scott Marks, DuPont
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