Fabricating a part with oriented polymer chains
3

Question

Fabricating a part with oriented polymer chains

farzadinjast (Mechanical)

(OP)

22 Sep 17 18:35

Hi,

I am thinking about the possibility of making a part from PA6 or 6/6 with a highly oriented structure. I mean I need to have, for example, a disk with all the polymer chains inside it pointed toward its center. Is this possible?
The size of the part would be around 4 inches.

farzadinjast (Mechanical) · Answer 1 · 2017-09-25 18:52:05

RE: Fabricating a part with oriented polymer chains

farzadinjast (Mechanical)

(OP)

25 Sep 17 18:52

Any suggestions?

Demon3 (Materials) · Answer 2 · 2017-09-26 13:38:30

Polymer chains automatically become orientated in the direction of flow, especially at high shear rates. That means that if you injection mold your disc with a thin wall and rapid flow and the injection point is at the center of the disc then the chains will orientate as you desire. You can detect the orientation using polarized light. You will also detect it from the mechanical properties where the strength and stiffness will be higher in the flow direction than they are at 90 degrees to it.

Chris DeArmitt PhD FRSC
President

Plastic materials consultant to the Fortune 100
www.phantomplastics.com

rickfischer51 (Mechanical) · Answer 3 · 2017-09-26 14:59:32

What Demon3 said is true at the surface, but in the center of the thickness the fibers may orient circumferentially. If the thickness is small, this effect is minimized, but if the disk is thick, it could be significant. You may want to consider some flow simulation to confirm you are getting what you want.

Rick Fischer
Principal Engineer
Argonne National Laboratory

Pud (Mechanical) · Answer 4 · 2017-09-27 10:19:38

If you are not fixed with nylon, a very thin disc, centre fed and using Liquid Crystal Polymer will get you very oriented molecules. LCP has a very "fibrous" appearance at fracture. It is also able to be moulded in very thin sections.
It's not cheap.

www.tynevalleyplastics.co.uk

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farzadinjast (Mechanical) · Answer 5 · 2017-09-27 23:11:49

I appreciate your replies.

I was thinking about making the disc with a different approach: By using the thin fibers of the Nylon, which surely are oriented in the longitudinal direction, and press them into a circular or conical die and then annealed it to keep the shape. Is it a feasible process?

Pud (Mechanical) · Answer 6 · 2017-09-28 11:34:52

Feasible? Maybe, but you'll get a thicker part at the centre than the circumference if the fibres are all the same length.

www.tynevalleyplastics.co.uk

Politicians like to panic, they need activity. It is their substitute for achievement.

IRstuff (Aerospace) · Answer 7 · 2017-09-28 13:20:45

What is the purpose? There are optical fiber bundles for direct imaging that are bundled and the heated and drawn to reduce the overall diameter:
https://www.edmundoptics.com/optics/fiber-optics/f...

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Fabricating a part with oriented polymer chains
3