The pervaporation properties of poly lactic acid (PLA), a natural source polymer, were studied in a polar/non-polar case study. PLA/PVP (poly vinyl pyrrolidone) blend membranes were prepared containing different PVP contents and evaluated in ethanol/ethyl tert-butyl ether azeotropic separation. The swelling and mechanical properties of the membranes were investigated. SEM cross-sectional images showed a porous structure at higher PVP concentrations. The degree of swelling as well as the permeation flux (0.05-1.36 kg/m(2) h) gradually increased when the PVP amount increased to 21 wt%. On the other hand, the EtOH separation factor initially raised to 16 using 3 wt% PVP and then decreased to 3 using 21 wt% PVP. The continuously decreasing water contact angle from 74 degrees in PLA to 54 degrees confirmed higher hydrophilicity and EtOH affinity at higher PVP contents. However, the more porous morphology and the plasticization effect resulted in selectivity decrease. This was also in agreement with the observed mechanical behavior of the blends. At higher EtOH concentrations and PVP contents, the elastic modulus of the membranes decreased, contrary to the membrane elongation. (C) 2011 Elsevier B.V. All rights reserved.