Posts: 4
From:india
Registered: Jun 2005

posted June 14, 2005 12:16 PM               

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kindly suggest the suitable combination of pvc compound for mfr.of pvc pipe with good quality of surface finish and good mechanical properties.
regards,

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Posts: 91
From:Silver City, NM, USA
Registered: Jun 2001

posted June 15, 2005 05:28 PM               

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I assume you are referring to rigid PVC pipe compound, which will be made as a dryblend in a high intensity mixer, and extruded on twin screw extruders? Any other approach (pelletized,or single screw extrusion) will be non competitive and counterproductive in my opinion.

Having said that, here is a formulation for Type I pressure water pipe that should work well-----made as a dryblend powder mix and extruded on counter rotating parallel or conical twin screw extruders:

PVC--K65-67----------------100 parts
TiO2 (Rutile)----------------1.0-2.0 parts
CaCO3 (1-2 micron)-----------3.0-5.0 parts
Tin mercapto ester
Stabilizer-------------------0.4 parts
Ca Stearate------------------0.4 parts
165 paraffin wax-------------1.2 parts
AC629A PE wax----------------0.25 parts
K-120N acrylic process aid
(Optional for smoother melt)--1.5 parts
If grey pipe instead of white,
add a pinch of carbon black.

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Posts: 4
From:india
Registered: Jun 2005

posted June 18, 2005 12:22 AM               

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how long we can extend the percentage of filler in pvc pipe compound for raw material cost cutting and what is the role of plastisizer in rigid pvc pipe, is it for makeing it unbreakable.?

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Posts: 4
From:india
Registered: Jun 2005

posted June 18, 2005 12:22 AM               

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how long we can extend the percentage of filler in pvc pipe compound for raw material cost cutting and what is the role of plastisizer in rigid pvc pipe, is it for makeing it unbreakable.?

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Posts: 91
From:Silver City, NM, USA
Registered: Jun 2001

posted June 18, 2005 11:26 AM               

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If your pipe is for pressure water systems (potable), do not go above 5phr filler. For non pressurized sewer or irrigation, you could go up to 20phr filler. But do not be fooled in thinking that adding larger amounts of filler really reduces costs! True,filler is cheaper, and the compound cost per kilo is lower,but filler has a much higher specific gravity,meaning that one meter of pipe is heavier--- your pipe is sold by the length (volume), so you need to do a "pound/volume" cost to see actual costs per unit volume (cubic foot,cubic meter).

As to plasticizer---THERE IS NO PLASTICIZER IN RIGID PVC PIPE!!!! Any plasticizer would reduce physical properties such as impact,heat distortion,etc. An option would be to use 3-5phr impact modifier like MBS,or Acrylic.

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