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preface to fifteenth edition

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10.6 GAS PERMEABILITY<br />

TABLE 10.5<br />

Gas Permeability Constants (10 10 P)at25C for Polymers and Rubbers<br />

The gas permeability constant P is defined as<br />

amount ofpermeant<br />

P (area) (time) (driving forced across the film)<br />

The gas permeability constant is the amount ofgas expressed in cubic centimeters passed in 1 s through a<br />

1-cm 2 area offilm when the pressure across a film thickness of1 cm is 1 cmHg and the temperature is 25C.<br />

All tabulated values are multiplied by 10 10 and are in units ofseconds 1 (centimeters ofHg) 1 . Other temperatures<br />

are indicated by exponents and are expressed in degrees Celsius.<br />

Gas<br />

Polymer or rubber<br />

He N 2 H 2 O 2 CO 2 H 2 O Other<br />

Cellulose (cellophane) 0.005 20 0.003 2 0.006 5 0.002 1 0.004 7 1 900 0.006 45 (H 2 S); 0.001 7 (SO 2 )<br />

Cellulose acetate 13.6 20 0.28 30 3.5 20 0.78 30 22.7 30 5 500 3.5 30 (H 2 S); 17 0 (ethylene oxide);<br />

6.8 60 (bromomethane)<br />

Cellulose nitrate 6.9 0.12 2.0 20 1.95 2.12 6 290 57.1 (NH 3 ); 1.76 (SO 2 )<br />

Ethyl cellulose 400 30 8.4 30 87 20 26.5 30 41.0 30 12 000 20 705 (NH 3 ); 204 (SO 2 );<br />

420 0 (ethylene oxide)<br />

Gutta percha 2.17 14.4 6.16 35.4 510<br />

Natural rubber 9.43 52.0 23.3 15.3 2 290 15.7 (CO); 30.1 (CH 4 );<br />

1.68 (C 3 H 8 ); 98.9 (C 2 H 2 );<br />

550 (CH 3 C#CH); 3.59 (SF 6 )<br />

Nylon 6 0.53 20 0.009 5 30 0.038 30 0.10 30 177 0.33 30 (H 2 S); 1.2 20 (NH 3 );<br />

0.84 60 (CH 3 Br)<br />

Nylon 11 1.95 30 1.78 30 1.00 40 0.344 30 (Ne); 0.189 40 (Ar);<br />

13.6 50 (propyne)<br />

Poly(acrylonitrile) 0.000 2 0.000 8 300<br />

10.66

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