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Author
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Topic: Molecular Orientation
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Want2Know
Member Posts: 2
From:Hammond, IN, USA
Registered: Aug 2002
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posted August 19, 2002 12:23 AM
   
Is there any way to achieve the same molecular orientation in an extruded wire insulation coating that is present in a tubed wire insulation coating for a given PVC plastic. I have found tensile strengths in the tubed version to be much greater than in an extruded version. I would like to find a way to produce the higher tensile strength in the extruded coating.IP: Logged |
talisman23
Senior Member Posts: 9
From:Chennai,Tamilnadu.INDIA
Registered: May 2003
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posted May 28, 2003 10:53 PM
Hi,
Can u be a little more elaborate? Are u meaning extruded PVC on to Cu wire, like the domestic wires and cables for extrusion and when you mean tubed? what does that mean?
Tubed means=??
bye
sriram.m.v.IP: Logged |
TomBlack
Moderator Posts: 36
From:
Registered: Jul 2002
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posted May 29, 2003 07:29 PM
Well, we're talking about alot of things here as molecular orientation has alot to do with molecular weight and distribution along with tooling design issues such as land length and entrance angles, along with process parameters which affect viscosity. Further, all that you do to affect orientation upstream of the die lip can be for not if your downstream cooling is not considered. The truth is that cooling may have the largest effect on orientation rate. Depending on what polymer you are using, you may even want to consider post extrusion stretching of the final product. Running a finished product through a pre-heater and stretching it will lead to tremendous orientation and thereby tensile strength. tom black ------------------
Tom Black
PPS, Inc.
www.ppsincorp.com IP: Logged |
alpertl
Senior Member Posts: 33
From:Fremont, CA USA
Registered: May 2002
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posted October 30, 2003 03:25 PM
quote:
Originally posted by Want2Know:
Is there any way to achieve the same molecular orientation in an extruded wire insulation coating that is present in a tubed wire insulation coating for a given PVC plastic. I have found tensile strengths in the tubed version to be much greater than in an extruded version. I would like to find a way to produce the higher tensile strength in the extruded coating.
Since the pressure coat process will not give you the chance to orientate the polymer in the extrusion direction as a tube on application, you may need to perform a downstream process or add to your original.
It seems you prefer the dimensional stability and bonding of the pressure application, but want the physical characteristics of the tube style process. What resin are you using? Can you xlink (peroxide additives)? Ebeam can be costly ($500 or so an hour), but there are plenty of vendors around. Can you reorient the coating over the wire on some type of dual capstan and a drawing die?
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