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Casting PVC

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Unread postAuthor: Eddbot » Wed Jun 18, 2008 11:44 am

but does it say what temperature it burns?
otherwise i would go with psycix idea of a vaccum
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Unread postAuthor: jimmy101 » Wed Jun 18, 2008 11:48 am

rp181 wrote:When will people look at wikipedia?

It says it melts at 80 degrees celcius, so in boiling water. It seems when people "soften" it, it really melts. PVC is probably just really viscous, as it also has a really high density.

Wikipedia is wrong. PVC does not melt at 80C. At 100C (boiling water) it is soft, press it onto a form then let it cool and it will partially spring back to its orginal shape when removed from the form. So PVC's true softening temperature is a bit higher than 100C.

According to http://www.machinist-materials.com/comp ... astics.htm , the melting point of type I PVC is 360F (182C).
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Unread postAuthor: psycix » Wed Jun 18, 2008 2:52 pm

And what is the temperature PVC ignites at?
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Unread postAuthor: LGM » Wed Jun 18, 2008 3:03 pm

This would be a lot more trouble than it's worth. You would probably be better off dissolving the PVC in something, then pouring/pressing it. If you wanted to try sintering you might get somewhere.
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Unread postAuthor: jimmy101 » Wed Jun 18, 2008 4:50 pm

LGM wrote:This would be a lot more trouble than it's worth. You would probably be better off dissolving the PVC in something, then pouring/pressing it. If you wanted to try sintering you might get somewhere.

Ya, there are much better thermoplastics if you really want to use a mold. Or, like others have said, use a casting resin or expoxy.

Dissolving the PVC in a solvent (like acetone or THF) then casting with the liquid probably won't work. The solvent won't be able to escape from inside the mold. If you take PVC glue, pour it into a small container so it is say 1" thick, and let it sit open to the air, it takes many days to fully harden. And even then it is still much softer than PVC should be. It'll also contain voids and have other structural problems. I certainly would'nt trust it to hold any kind of pressure or load.
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Unread postAuthor: psycix » Thu Jun 19, 2008 4:30 am

Casting PVC may have alot of cons, but the big advantage is, that almost everyone can get it.
I will have to cross trough half the country if I wanted to buy epoxy resin or some thermoplastic, while PVC is 5 minutes on the bike away.
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Unread postAuthor: LGM » Thu Jun 19, 2008 9:53 am

PVC pipe isn't very pure PVC. Someone on APC tried to use PVC pipe in place of pure PVC as a chlorine donor in a star composition, but it didn't work. Casting it might be difficult if there are different materials that may change the properties of the pipe once it is in it's shape. If you want to order PVC powder from a pyro site go ahead and try that. I would stick with sintering, just pack a mold tight with some powder from a pipe and throw it in an oven at 350ish.
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