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| Author | Topic: Cloudy PETG |
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vmping Member Posts: 2 |
posted August 22, 2007 08:32 AM
  
We have been producing PETG sheet. When ever we add regrind the sheet becomes cloudy. We blend our regrind with virgin then dry it. If we get above 15% the sheet becomes unacceptable, we would like to be able to run 30% to 40%. Material moisture at the feed throut is around .020% melt temp is 435F. Any suggestions? vmping IP: Logged |
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Tom C Moderator Posts: 886 |
posted August 22, 2007 02:31 PM
Possible issues; Contamination Is it cloudy coming out of the die, and/or after it cools? ------------------ Tom Cunningham www.ExtrusionTechnicalServices.com IP: Logged |
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vmping Member Posts: 2 |
posted August 23, 2007 07:50 AM
This is a closed loop system. Not to say contamination is impossible, but hopefully unlikely. We have sent samples out to be tested by Eastman for varification of this. I will be proforming melt flow tests today on our regrind. Looking for possible degradation. We are proccessing this material with a single stage screw. We are not venting. Please explain more about "Distruption of stagnent screw surfaces". Finaly the material is cloudy as it exits the die before it is cooled. Thank you for your help. vmping IP: Logged |
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