%0 journal article %@ 0014-3057 %A Escorial, L., de la Viuda, M., Rodriguez, S., Tena, A., Marcos, A., Palacio, L., Pradanos, P., Lozano, A.E., Hernandez, A. %D 2018 %J European Polymer Journal %P 390-399 %R doi:10.1016/j.eurpolymj.2018.04.031 %T Partially pyrolized gas-separation membranes made from blends of copolyetherimides and polyimides %U https://doi.org/10.1016/j.eurpolymj.2018.04.031 %X For neat blends, permeability was shown to decrease when PEO content increases. This effect is due to polyethylene oxide (PEO) chains encroaching on free volume because phase segregation was minimized. When these blends were subjected to thermal treatment at relatively low temperatures in air or in N2, it was clearly observed that all the polyether moieties were selectively eliminated from the structure, which gave rise to an increase of permeability. Higher permeabilities were obtained after a thermal treatment at 390 °C in N2. Degradation of PEO chains after a 290 °C treatment in air produced materials with permeability values lower than those observed under N2. In both cases, even though PEO was selectively and wholly eliminated, permeability was not totally recovered to give the values observed for neat 6FDA-6FpDA due probably to a combination of shrinkage and crosslinking of the membrane produced during the thermal process. Crosslinking provides the materials with an increased resistance to plasticization. In particular, the best improvement against plasticization proceeded from the thermal treatments of blends at 290 °C in air.