Can you DIY thermoform Viton sheets?

[Stormer]

Viton rubber is pressure molded with heat or injection molded to form complex gaskets from what i have read. But do it behave like a thermoplastic where you can for example buy a sheet of finished Viton rubber, heat it up and then vacuum form it to the shape you want? Or is it more like thermoset resins where you can not heat it up and form it again after it has been done one time?

 

[Tom.G]

Here is the answer you don't want: "Maybe"

A Google search
(https://www.google.com/search?&q=softening+temperature+Viton)
returned many results for processing, usage, and cautions.

The first search hit was:
https://www.google.com/url?esrc=s&q...YQFXoECAUQAg&usg=AOvVaw1PSw6Q55Ua7EnV4qRM8WbR

Which states that the curing agent should be mixed with the fillers then added to the polymer. It also refers to the curing as "vulcanizing."

The document closes with:
"For more information, visit Viton.com"

 

[Baluncore]

"Viton seals provide an indefinite seal for temperatures up to 400°F, and for temperatures up to 600°F they offer an excellent seal for more than 48 hours."
https://www.humphrey-products.com/news/viton-vs-buna-which-seal-for-your-applications
Which tells you that Viton does not flow when heated up to 600°F.

But do it behave like a thermoplastic where you can for example buy a sheet of finished Viton rubber, heat it up and then vacuum form it to the shape you want?

You cannot change the shape of cured Viton by heating it.

In general, elastomer seals that are overheated develop more cross-links, so they become harder and more brittle. With Viton, that begins to happen slowly above 400°F, then rapidly above 600°F. Being less flexible results in a poor seal that may fracture, or will not remain compliant with the surfaces of the gaps it is sealing.

 

[Stormer]

Ok. So i guess it is more like a thermoset material. Is there anywhere for a DIY'er where you can buy Viton that is not cured so you can make your own custom shaped high temperature gaskets?

 

[Baluncore]

https://www.martins-rubber.co.uk/blog/what-is-viton-our-essential-guide/
Write ... "Viton® is a brand name of DuPont for its synthetic rubber and fluoropolymer elastomer, commonly used in O-rings and other moulded or extruded products. This family of elastomers comprises copolymers of terpolymers of tetrafluoroethylene (TFE), hexafluoropropylene (HFP) and vinylidene fluoride (VDF or VF2), vinylidene fluoride (VDF) and hexafluoropropylene (HFP) as well as perfluoromethylvinylether (PMVE) containing specialty polymers".

To cast your own equivalent elastomers will be difficult because you will need to blend the components to get the required final chemical and mechanical properties.

You may be able to buy a two part kit from a resin supplier, or from a DuPont agent.

I would want to check first why you need to use a "Viton® like" polymer, and why a two part silicone compound would not be a much easier material to obtain, cast and cure. What are you trying to make, and why must it use Viton®.

 

[Stormer]

I would want to check first why you need to use a "Viton® like" polymer, and why a two part silicone compound would not be a much easier material to obtain, cast and cure. What are you trying to make, and why must it use Viton®.

I want to make some rolling diaphragm seals for a pressurized Stirling motor so i don't have to pressurize the crankcase. So the material needs to be both heat resistant and relatively strong (it will be backed up with pressurized oil). Maybe silicone will work if i get a hard enough type? But i don't think the really soft type of silicone i have usually seen will work for this.

It will be in the cold side of the cylinder, but still i don't think normal thermoplastic elastomers like the flexible 3D printer filaments are made of will take the heat the "cold side" can get up to without softening to much and failing.