[moatasa]

Hello,

I am not a chemist, but I have this question.
I have a 30 cm steel wire 0.8mm diameter covered with plastic 1.2 mm diameter, to form a wire of 2mm diameter.

How I can make this wire more rigid, is there a process I can do, is there a chemical I can add or coat it with.

I searched a bit and I saw some people boil RC plastic parts for some minutes and they say it make it more rigid.

Can someone please help me to understand, or what to do.

Thanks:
Moatasa.

[Enthalpy]

The stiffness of a wire goes like Φ⁴E where Φ is the diameter and E is Young's modulus.
To be as stiff as 0.8mm steel with E=210GPa, a 2mm polymer wire needs E=5.4GPa which is easy.

I can't tell what kind of polymer would get stiffer when boiled; maybe PVC releases its plasticizer then (don't swallow the water) to becomes stiff but brittle. Most polymers wouldn't react, some would get very weak when hot.

If you can accept some diameter increase, the efficient way would be to add some fibres+epoxy around the wire, roughly parallel to it.

Or can you get a thicker naked steel wire
https://en.wikipedia.org/wiki/Piano_wire
and cover it with thinner polymer? Heat shrink sleeve
https://en.wikipedia.org/wiki/Heat-shrink_tubing
is common for electrical engineering, available in many colours and diameters, rather thin.

[P]

UV? Although, it would also depend on what type of polymer it is..  For example, some polymers undergo crosslinking with UV light. Crosslinking in the polymer will probably increase the stiffness. However, some polymer undergo chain scission or even complete unzipping under UV, which will obviously have the opposite effect.

[P]

As a question - why does it need to be more rigid? Maybe there is another fix, like taping the wire along the length to increase its thickness, or taping it to a stiffer rod. If it is only 30 cm long then could you fix it to another, stiffer rod? What's the application?

[moatasa]

Hello,

Thanks for all the replays, well I can't use a stiffer rod, so that's not an option, for the UV, normally I will be using recycled plastic PVC so I am not sure if it will work.

Any other suggestions.

If I add two coats of pvc does that help, like I can start by adding 0.6mm, then I add another layer of 0.6 mm.

Thanks:
Moata.

[P]

What is the application? If we knew that we might be able to offer a solution...  For example, right now I can't see why just taping the wire to a rod or running it through a plastic pipe wouldn't work to give it the stiffness you require. Or by thickening the insulation up with tape....  If we knew the application then we would know why this wouldn't work and wouldn't suggest it - there night be a simple fix that we are not coming up with because we do not know what you are trying to do.

Why does it need to be stiff?

[Enthalpy]

[...] If I add two coats of pvc does that help? [...]

Yes, computationally. I just wonder how to "add" them, because if they are wrapped for instance, the joints will likely make them little stiff.

Glass or graphite fibres plus epoxy were a similar attempt, but with a clear procedure.

[P]

Did we suggest a lacquer? A hard shellac like lacquer/varnish coating over the plastic might stiffen it up...

I still think it would be better if we knew the application.