Kinetic free volume controlled gas separation properties of glassy polyheteroarylenes

Molecular packing density in the crystalline state of semi‐rigid chain polymers. I: Polyimides

“…These findings are relevant to understanding the bulk properties of, not only crystalline polymers [e.g., bulk modulus (lo)], but of amorphous polymers as well. In fact, it can be shown that the molecular transport-related properties of the latter [such as activation energy for viscous flow (10, 181, gas transport parameters (19,20) 1 -K,/K, (where K , is the molecular packing coefficient in the amorphous state). Considering that the value of K , for the majority of glassy polymers is essentially constant at Tg (9).…”