Expanding polymeric beads/ pellets

[will123]

Is anyone able to point me in the direction of a company who can supply beads or pellets of a polymer material that can undergo preferably an irreversible expansion or swelling when exposed to elevated temperatures (above 100°C)- basically I require a more controlled version of popcorn!!! I can also work with a material that undergoes a reversable expansion with temperature - as long as the magnitude is greater than the usual thermal expansion. The intention is to use this effect to provide internal pressure during cure of a hollow composite moulding when a bag is not suitable.

 

[Demon3]

Yes, Expancel

http://www.expancel.com

it's an Akzo Nobel company


Chris DeArmitt

 

[patprimmer]

Try a web search on Expandable Polystyrene or EPS. BASF is a big player in that field but there are numerous suppliers.

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers for professional engineers

 

[NunoH]

Hi.

If you could provide more details on the shape of the part, we could be of more help.

For instance, what to do you with the material inside of the hollow product? Does it have to stay there; be part of the structure?

If it is soemthing like a open hollow part (such as a tube) you can a inflatable sleeve. As you imagine there are some drawbacks, namely on finishing (but I deduct it is not a concern in your application) in using this process.
There are some companies that use it, for instance for composite poles.

Why not use highly-pressurised air? Is it a closed part or could leak the air?

I am not sure on costs, but in Gas-assisted injection moulding, some processes use super-critical fluids. These basically evaporate and may provide enough pressure.

On EPS

http://www.plasticseurope.org/Content/Default.asp?PageID=1194

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