# Special material

1. Feb 22, 2009

### nour naser

hii... i need to know about materials that we can use in airships using helium ... i mean material which has these properties : 1) less penetration to helium 2) elastic 3) implement high pressure 4) resistence for heat 5) insulate the helium from the outer temperature ..... thank u soo much for help .

2. Feb 22, 2009

### Astronuc

Staff Emeritus
Those are contradictory properities.

By elastic, does one mean elastomeric or 'stretchable'?

Polymers are often used, as opposed to metals. The problem is that polymers are relatively permeable to He. One needs a tight structure like metal, e.g. Al, so aluminized (metal) mylar (polymer) balloons are use to contain He.

Polymers, e.g. Kevlar, can have high strength. The problem with a metalized polymer would the be the high strain if the polymer is stretched, but one way around this would be to coat a polymer while it is stretched.

To minimize mass, the balloons are thin which means little resistance to heat transfer. Both H2 and He have relatively high thermal conductivity as gases go.