looking for a non newtonian fluid- Bingham fluid 4

[Evila]

Hi!
Im looking for a polyolefin (a polypropylene, polyethylene...) that can be processed at a range temperature from 100°C-130°C, and that behaves as a Non newtonian - Bingham fluid. In other words that when melted it can be pushed through but firm enough that it will "stack up".
I know it´s hard to find a polymer that can be melted at that temperature and still get a non Newtonian behavior but it´s worth the shot.
Thanks for your time.

Sincerely Evila Melgoza

 

[Demon3]

All polymer melts are non-Newtonian.

To produce a shear stress that needs to be overcome to induce flow (i.e. Bingham fluid) add filler. They give that effect as a certain energy is needed to overcome the forces agglomerating the filler.

For a good book on this try this book. I have it at home:

http://www.amazon.com/Rheology-Filled-Polymer-Systems-Shenoy/dp/9048140293

Chris DeArmitt PhD FRSC CChem

 

[unclesyd]

With Nylon Polymer we don't have a lot of fillers but we do have additives that tend to drop out in the low shear areas when we have complete polymerization. To keep the additives moving we move the Polymer by gear pump under relatively high pressure to the spinneret pack where another gear pump meters the polymer through a high shear sand pack and then takes a high pressure drop across the spinneret. All that happens at around 283 degrees C, out of your range.

Demon3, might be able to elaborate on the following.

We compound all our additives and finishes for the polymer process. Several of the processes use Microcrystalline waxes and oils the make a finish. These have to go through a high shear mixer to enable pumping.

Another area where we did a lot of work was with Poly Ox (Polyethylene Oxide) I over heard discussions during several meetings about what war happened to the material a high pressure. There was discussion of whether or not the fluid was non-Newtonian or jsut elastic.

Our group was also working with Ply-OX during this peroid as and additive to UHP water (55,000 psig). We busted intensifier head so our money was cut off. Our problem was that we could never duplicate the results.

 

[patprimmer]

You should be able to reach the melting points with some LDPE grades, maybe Metallocene catalyst types.

Another possibility is EVA.

Plasticised PVC could also do it with the appropriate level of plasticiser.

Regards
Pat
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[Demon3]

Polyethylene oxide of high molecular weight is added to the water used in fire trucks as it makes the water squirt much farther. I have not read a definitive answer how it works but it's speculated that the PEO makes the water flow in a more laminar way.

Interestingly PEO should not be water soluble. POM isn't and neither is polypropylene oxide on the other side chemically. The reason PEO is water soluble despite having the wrong polarity in theory is that it forms a helix in water where the water molecules dock perfectly between the chains in each helix. The special interaction imparts the water solubility.

I did a study on PEO and all other water soluble polymers many years ago. We wanted a thickener and binder for a ceramic formulation. It had to survive a high shear mixer but none of the normal ones do. If you have a high enough molecular weight to thicken, the chains are too long to get out of the way of the mixing blades so the chains are chopped up and you lose all thickening performance in under a minute.

The only way around it is to use associative thickeners as they are lower molecular weight and thicken through a different mechanism (association of hydrophobic groups into micelles).

Not sure any of that answered your question but I think strands of an answer are there.

Chris DeArmitt PhD FRSC CChem