Free-Volume Studies in Polycaprolactone/Poly(propylene oxide) Urethane/Urea Membranes by Positron Lifetime Spectroscopy
M.F. Ferreira Marques a, b, P.M. Gordo b, A.P. de Lima b, D.P. Queiroz c, M. Norberta de Pinho c, P. Major d and Zs. Kajcsos d
a Department of Chemical Engineering, Instituto Superior de Engenharia, 3031-199 Coimbra, Portugal
b ICEMS, Department of Physics, University of Coimbra, 3004-516 Coimbra, Portugal
c Department of Chemical Engineering, Instituto Superior Técnico, 1049-001 Lisboa, Portugal
d KFKI Research Institute for Particle and Nuclear Physics, P.O.B. 49, 1525 Budapest, Hungary
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Received: 3 09 2007;
Positron annihilation lifetime spectroscopy was used to study the free volume parameters in polypropylene oxide-based tri-isocyanate terminated prepolymer/polycaprolactone diol bi-soft urethane/urea membranes (PU/PCL) with PCL content from 5 up to 25 wt%. Positron annihilation lifetime spectroscopy measurements carried out in the temperature range 298-324 K mirrored the phase separation of the various soft and hard segments present in the membranes. The size and amount of free volume holes determined by positron annihilation lifetime spectroscopy appear to be correlated with the CO2 gas permeability through the membranes.
DOI: 10.12693/APhysPolA.113.1359
PACS numbers: 61.41.+e, 78.70.Bj, 82.30.Gg