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Voids in extrudate

Author	Topic: Voids in extrudate
Even Member Posts: 2 From: Registered: Mar 2004	posted April 20, 2004 06:39 AM Hello. I`m a student at the Norwegian University of science and technology. I work on my head project in my last semester. My goal is to make compounds of PP and glass fiber for injection moulding. My problem is that the extrudate from the compounding machine contains a lot of voids (probably air entrapments). Do any of you have some appropriate technique for eliminating this? Very happy for answer IP: Logged
zabielski Senior Member Posts: 308 From:McHenry, IL USA Registered: Nov 2002	posted April 20, 2004 07:28 AM Use a coupling agent, and make sure you use constant feed rates. IP: Logged
Tom C Moderator Posts: 318 From:Brodheadsville, PA USA Registered: Jun 2001	posted April 20, 2004 07:46 AM Even, The voids are due to insufficient wetting of the fiberglass by the PP. You may need to take several steps to improve the situation. In order of importance: 1) Make sure the fiberglass is designed to be used with PP. 2) Improve mixing in the extruder. This system can tolerate a fair amount of mixing. 3) As mentioned, using a coupling agent will help. Polybond by Crompton is one I know that works. 4) Vacuum venting will densify the product nicely. Good luck. Tom Cunningham Extrusion Technical Services IP: Logged

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