In this study, the functionality of maleic anhydride was utilized in the maleic anhydride-styrene-methyl metacrylate (MAStMMA) terpolymer. First, the polyester of poly(ethylene adipate), PEA, polycondensation copolymer was synthesized from ethylene glycol and adipic acid monomers. PEA was then modified on its maleic anhydride units in the MAStMMA terpolymer which has been synthesized previously. This modified copolymer was characterized by FTIR (Fourier Transform Infrared spectroscopy). The viscosimetric and thermomechanical characterization of MAStMPAA terpolymer and its modified copolymer were also performed and the results were compared. The modified copolymer obtained was found to be more elastic and more soluble, and had lower viscosity and density. (c) 2006 Elsevier B.V. All rights reserved.