Synthesis and Characterization of Aliphatic-Aromatic Copolyesters From Pet Waste and ε-Caprolactone

Copolyesters containing aliphatic units in the main chain were obtained by reacting Bis(2-hydroxy ethyl terephthalate) (BHET) with epsilon-caprolactone (epsilon-CL) at a high temperature in bulk in the presence of tin octoate as catalyst. Various copolyesters were synthesized by using BHET/epsilon-CL mass ratio ranging from 90/10 to 10/90. Thermal properties were studied by DSC and TGA, and structural characterization was carried out by H-1-NMR spectroscopy. These techniques confirm the insertion of lactones units in PET chains. The degree of randomness of 30/70 to 60/40 copolyesters, determined by H-1-NMR, shows a random microstructure. The other copolyesters exhibit some block copolymer character.