| |
|
|
|
| Gas permeability |
| Compared to organic rubber or plastic films, thin films of silicone rubber have better gas and vapor permeability, and they have selectivity. One application for silicone rubber being investigated is as a gas and water separation membrane in oxygen enrichment systems. |
| Comparison of gas permeability with natural rubber=100 for reference (25∑C) |
Material |
H2 |
O2 |
N2 |
CO2 |
Air |
Natural rubber |
P x 108^cc.com |
37.4 |
17.7 |
6.1 |
99.6 |
- |
cm2·sec·atm |
|
100 |
100 |
100 |
100 |
100 |
Silicone |
1070 |
2200 |
3300 |
1600 |
2700 |
Butyl rubber(isobutene 98,isoprene) |
15 |
56 |
5 |
4 |
48 |
Polybutadiene(emulsified) |
86 |
82 |
80 |
105 |
81 |
Nitrile |
Acrylonitrile |
20% |
51 |
35 |
31 |
48 |
33 |
27% |
32 |
17 |
13 |
24 |
15 |
32% |
24 |
10 |
7.5 |
14 |
8.5 |
Teflon |
46 |
44 |
43 |
19 |
- |
Polyethlene d=0.9296 |
15 |
11 |
9 |
8 |
- |
polypropylene |
23 |
7 |
9 |
4 |
- |
Polyvinyl chloride |
6 |
2 |
2 |
1 |
- |
|
| |
| Water vapor permeability of plastic films |
Material |
Water vapor permeability |
silicone rubber |
15.5-51.8 |
pva |
0.04-40.0 |
ethyicellulose |
21.5 |
polylethyiene |
0.05-4.85 |
polytetrafluoroethylebe(PTFE) |
2.94 |
Polycarbonate |
1.0 |
Nylon |
0.32-0.63 |
|
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