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| Author | Topic: Pebax processing |
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Plank Senior Member Posts: 5 |
posted February 29, 2008 03:37 PM
  
We are trying to process some pebax monofilament on a lab extruder, but are having problems with gels/ unmelts in the strand causing it to break. I believe from previous posts that gels etc. in pebax is a common industry problem. Is there one type of filter, or other processing advice that would help overcome this? Any advice would be appreciated. IP: Logged |
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Tom C Moderator Posts: 907 |
posted February 29, 2008 07:01 PM
Some monofiliment extruders are run very slowly causing long residence times. Various thermal and oxidative reactions occur causing problems. Do you think this might be the case? What is your screw diameter and RPMs? ------------------ Tom Cunningham www.ExtrusionTechnicalServices.com IP: Logged |
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Plank Senior Member Posts: 5 |
posted March 01, 2008 01:23 PM
20mm with some 80/80 square weave screens. We have varied the rpm from 5 - 25. Even when we have run thicker strands, we have noticed some visible defects in the product. Tried low/ high extrusion temperatures. IP: Logged |
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Tom C Moderator Posts: 907 |
posted March 01, 2008 01:46 PM
Your output rate is so low that dead spots on the screw and die will create problems. I would first move to a supported 325 or 400 mesh sceen. If that is not good enough, then try stacking multiple 325 mesh screens to trap gels. A smaller size extruder would probably be advisable, along with a screw and die that are designed to be self cleaning. The screw should also assure a completetly melted resin. I can provide all of the above if you are interested. Tom Cunningham www.extrusiontechnicalservices.com [This message has been edited by Tom C (edited March 01, 2008).] IP: Logged |
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