In this Study, the anhydride units in maleic anhydride-styrene-methyl metacrylate terpolymer (MA-St-MMA) were reacted with n-propyl, n-butyl, n-pentyl and n-benzyl alcohols, and the ester derivatives of MA-St-MMA terpolymer were obtained. These were named n-alkyl maleate ester derivatives, abbreviated as nPrMA-St-MMA, nBuMA-St-MMA, nPnMA-St-MMA and nBzMA-St-MMA. The aim of this Study was to obtain more elastic polymers by replacement with the maleic anhydride Units in MA-St-MMA terpolymer of alkyl groups having a linear chain structure. All the polymers synthesized were characterized by FT-IR, TMA, the solvent definition, the number of esters and solution viscosity. The TMA experiments of all the polymers were studied under increasing and temperature. All these Studies have showed that the n-alkyl maleate ester derivatives are more elastic than original MA-St-MMA terpolymer.