Posts: 2
From:uk
Registered: Nov 2003

posted November 15, 2003 05:02 AM            

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After spending a few years in the extrusion industry my knowledge of co-extruding certain materials is very limited. i would like some help in the co-extrusion of a poly-pro fin onto a pvc profile ( if it is possible ). i know that i can co-extrude tpe and poly-pro. Many Thanks.

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MW

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Posts: 249
From:McHenry, IL USA
Registered: Nov 2002

posted November 15, 2003 10:30 AM               

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Sure you do the co-ex, but there will not be a chemical bond. PP is non-polar, PVC is polar.

Even with a tie layer, it might work for awhile, but the plasticizers will slowly leach into the tie layer.

Why do you want to co-extrude these together in the 1st place?

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Posts: 249
From:McHenry, IL USA
Registered: Nov 2002

posted November 15, 2003 10:34 AM               

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By the way, you placed this in Injection Molding - Thermoset's. Your subject is on extrusion and thermoplastics.

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Posts: 2
From:uk
Registered: Nov 2003

posted November 17, 2003 06:01 AM            

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Thanks for the advice. Perhaps i need to learn more about basic plastic properties ( Any help would be appreciated in the co-extrusion of compatible materials ).However as there are no design specifics I have cured the problem by changing the carrier material to polypro also.

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MW

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Posts: 249
From:McHenry, IL USA
Registered: Nov 2002

posted November 18, 2003 07:19 AM               

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MW: If your wanting to co-ex with a softer compatable material (similiar softness of PVC) use EVA. Any Ethylene Vinyl Acetate supplier can help you select the proper material. However, you want to match the viscosity as close as possible under similiar shear rates that your PP see's.

Maybe you can ask your potential EVA supplier to do a reology study for you, and send them a small sample of the exact PP your using.

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