Biobased copolyesters from renewable resources: synthesis and crystallization kinetics of poly(propylene sebacate-co-isosorbide sebacate)

Abstract

In this work, a series of novel biobased copolymers, poly(propylene sebacate-co-isosorbide sebacate) (P(PSe-co-IS)), were synthesized by melt-polycondensation from sebacic acid (SA) and isosorbide (IS) with 1,3-propanediol (PD). In order to analyze the effects of isosorbide on the relative properties of poly(propylene sebacate) (PPSe), the composition, crystal structure, crystallization behavior, multiple melting behavior, and spherulitic morphology of these copolymers were investigated by ¹H-NMR, WAXD, DSC, TMDSC and POM, respectively. Results of ¹H-NMR indicated that IS have been successfully introduced into the PPSe main chains with the designed molar ratio. DSC data showed that crystallization ability of P(PSe-co-IS) copolymers was retarded with the introduction of IS. With the increment of IS, the overall crystallization rate decreased gradually. Furthermore, crystallization temperature (T_c), crystallization enthalpy (ΔH_c), melting temperature (T_m), and equilibrium melting temperature (T^o_m) of P(PSe-co-IS) copolymers also decreased apparently with the increase of IS content. WAXD suggested that crystal structure of PPSe was not affected by IS, and POM revealed that all spherulites possess the typical “Maltese Cross” image. Furthermore, no obvious ring-banded spherulites could be detected for P(PSe-co-IS) copolymers in the wide temperature range except neat PPSe due to the hindrance of IS. With the increment of IS and crystallization temperature, the number of spherulites decreased rapidly and the size of spherulites increased, respectively.