This study was aimed at the modulation of poly(lactic acid) (PLA) properties byt he addition of both a low-molecular-weight pasticizers, acetyl tributyl citrate (ATBC), and a biodegradable aliphatic-aromatic copolyester, poly(butylene adipate-co-terephthalate) (PBAT). PLA/PBAT, PLA/ATBC, and PLA/PBAT/ATBC mixtures with 10-35 wt % ATBC and/or PBAT were prepared in a discontinuous laboratory mixer, compression-molded, and characterized by thermal, morphological,a nd mechanical tests to evaluate the effect of the concentration of either the plasticizers or copolymers ob the final material flexibility. Materials with modulable properties, Young,s modulus in the range 100-3000 MPa and elongation at break in the range 10-300%, were obtained. Moreover, thermal analysis showed a preferential solubilization of ATBC in the PBAT phase. Gas permeability tests were also performed to assess possible use in food packaging applicaitons. The results are discussed with particular emphasis toward the effects of plasticization on physical blending in the determination of the phase morphology and final properties. (c) 2008 Wiley PEriodicals, Inc.