CARBON-DIOXIDE TRANSPORT-PROPERTIES OF COMPOSITE MEMBRANES OF A POLYETHERIMIDE AND A LIQUID-CRYSTAL POLYMER

The effect of the addition of a liquid crystal polymer (Rodrun) on the gas sorption and transport properties of a polyetherimide (PEI, Ultem 1000) was investigated. CO2 permeation and sorption measurements were made with films of PEI, Rodrun and heterogeneous PEI/Rodrun blends at different pressures and temperatures. In all cases, permeability, dif fusion and sorption coefficients decreased when the amount of Rodrun i ncreased. A good agreement was found when permeability data obtained u sing both a permeability cell and a Cahn electrobalance were compared. Permeabilities of the binary composite material were calculated on th e basis of those of the pure components and some theoretical assumptio ns concerning blend morphology. Results were consistent with a Rodrun structure in the composite intermediate between a fibrillar and a lami nar morphology, as electron microscopy evidenced experimentally, (C) 1 998 Elsevier Science Ltd. All rights reserved.