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Stretched Polymer

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Enthalpy:
Hello dear friends!

Stretching stiffens polymers a lot, making wonder fibres of banal bulk materials. It brings LCP from 10GPa to 170GPa. Highly stretched polyethylene makes wonder ropes of Dyneema, Spectra and competitors.

Stretching *3, easy with a polymer, strengthens much a stripe from a polyethylene shopping bag.

Companies that stretch metal (for piano wire and others) could adapt to thicker polymer too. Or polymer manufacturers themselves could stretch or extrude the material cold or lukewarm, so mechanical engineers have stiff strong bulk polymers, lighter and easier to machine without fibre reinforcement.

The transverse properties may drop. Rolling a polymer in two directions strengthens both, as polyester (Mylar) films show. This would improve plates.

Sometimes the azimuthal stiffness too matters for rods. Schrägwalzen (I ignore the English word, check the drawings)
https://de.wikipedia.org/wiki/Walzen#Schr%C3%A4gwalzen
would improve the azimuthal direction, easy with a polymer. Combine with stretching or extrusion.

Marc Schaefer, aka Enthalpy

Enthalpy:
PTFE too, and other weak polymers, are candidates for strengthening and stiffening. Making supermaterials is one goal, improving bad ones is one other. Creeping, flowing, low modulus all hinder the use of PTFE despite its other properties are good. Fibres exist already, hardened plates and rods would be nice.

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"Schrägwalzen" is "skew rolling" in English, while "transverse rolling" includes other interesting possibilities. Common at tube production, it serves for rods too.

Marc Schaefer, aka Enthalpy

Enthalpy:
Stretching might stiffen and strengthen polyketone too. Initial E=1.3GPa and σ~58MPa aren't brilliant, but polyketone is potentially very cheap, it has a good operating temperature range, low water absorption and high vibration damping. Maybe stretching brings a nice combination of properties.

Polymers used as super-fibres should also improve as bulk materials. PA and PET, PEEK too. Machining would become easier too, useful for PA.

Marc Schaefer, aka Enthalpy

marquis:
This has been done in the medical industry ( i.e. I.V. Bags) for at least 20 years.  Special polymers are still used for specific drugs, but not unless absolutely needed.

Thanks for pointing out the technique, though.

Enthalpy:
And it has been done for ropes since polymer ropes exist. Plus many films like Mylar, which was old stuff 30 years ago.

But I want more massive material hardened this way, for mechanical engineering, including wind instruments that badly need it. Rods, plates, and so on. From one or several companies that have them in catalogues with guaranteed properties, and preferably in stock. Polymers stiff and strong, that would open many uses in mechanical design.

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