Synthesis and characterization of poly(butylene succinate) and its copolyesters containing minor amounts of propylene succinate

High molecular weight poly(butylene succinate) (PBSu), poly(propylene succinate), and PBSu-rich copolyesters were synthesized using an effective catalyst, titanium tetraisopropoxide. The compositions of the copolyesters were determined in three ways from H-1 and C-13 NMR spectra, and good agreement between the results was obtained. The analysis of the carbonyl carbon spectra indicates a random distribution of the comonomers. Thermal properties were studied using a differential scanning calorimeter and a thermogravimetric analyzer. No significant difference exists among the thermal stabilities of these polyesters. However, the window between the glass transition and the melting temperatures becomes narrower with the increase in the concentration of propylene succinate in the copolymers. Additionally, the cold crystallization ability reduces considerably. Wide-angle X-ray diffractograms of isothermally crystallized copolyesters also follow the same trend.