Posts: 1
From:Beavercreek, Ohio USA
Registered: Apr 2005

posted April 22, 2005 02:29 PM               

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We are going to develop a profile using a 10% talc filled 55D Polypropelene material. What type of screw design would be recommended? We can run on a 3.5" 24:1 or 30:1 extruder, which would be recommended? We are used to running flex PVC and semi-rigid PVC.

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Posts: 503
From:Brodheadsville, PA USA
Registered: Jun 2001

posted April 22, 2005 07:56 PM               

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Chuck,

PVC screws will tend to be cut deeper and run slower than PP screw because PVC is higher in viscosity than PP.

The PP will be happier with the 30:1 screw. Try running slowly at first.

PP barrel temps run 400-500F.

I would be happy to discuss PP screws further. Please email.

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Best Regards,

Tom Cunningham

Extrusion Technical Services

www.ExtrusionTechnicalServices.com

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Posts: 5
From:stoney creek, on, canada
Registered: Apr 2005

posted April 26, 2005 03:35 PM            

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Chuck,
I agree with Tom regarding the PP barrel temps, and suggested L/D. Another consideration is higher temperatures in the first few zones and high mesh screen packs if dispersion is an issue (i.e. black material).
Cheers

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Posts: 365
From:McHenry, IL USA
Registered: Nov 2002

posted April 27, 2005 10:01 AM               

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While I agree with Tom, I disagree with Shyane 31.

If your simply compounding the talc to produce pellets, you want to run it trough a conventional breaker plate WITHOUT A SCREEN PACK - period. The screen pack(s) will simply plug up and NOT give you good dispersion.

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Posts: 5
From:stoney creek, on, canada
Registered: Apr 2005

posted April 27, 2005 10:57 AM            

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I guess that the proof will be in the process; millions of pounds can't be wrong.

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Posts: 5
From:stoney creek, on, canada
Registered: Apr 2005

posted April 27, 2005 11:00 AM            

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I apologize Chuck, I meant to include the following link: http://www.griffex.com/Griff-screensPT.pdf

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