AbstractPolyethylene terephthalate is a linear thermoplastic polyester. Different grades of this polymer are used in various industries with a wide range of molecular weights and the manufacturing of beverage bottles. Due to its abundant waste products, it has become a problem for the environment. In this research, polyethylene terephthalate was reacted with ethylenediamine, butylenediamine, and hexamethylenediamine at a ratio of polymer 1 to 6 of each reactant. Polymer was then reacted with hydrazine hydrate in different molar ratios at various time intervals. The effect of catalyst concentration on the reaction yields was studied. It was observed, that with the increase of aliphatic groups in the structure of the final product its melting point was lower which might have been due to the presence of more flexible methylene groups in the final structure.