GAS PERMEATION PROPERTIES OF SOME POLYPYRROLONES

The permeability of six different polypyrrolone membranes to H-2, O2 a nd N2 was determined at 30-degrees-C and 1 atm. The variations in chem ical structure were found to lead to significant changes in permeabili ties and selectivities. Substitution of 6FDA for PMDA in polypyrrolone appeared to result in a significant increase in gas permeability and a correspondingly large decrease in selectivity. Further analysis show ed that permeability and selectivity changes in these cases were prima rily due to the alteration of diffusivity factors. The relationship be tween gas separation properties and chemical structure is discussed in terms of intrasegmental mobility and intersegmental packing of the co nstituent polymers. The average segmental spacing of the materials mea sured by a wide-angle X-ray diffraction characterized the packing of t hese different polymers.