Tailoring the isothermal crystallization kinetics of isodimorphic poly (butylene succinate-ran-butylene azelate) random copolymers by changing composition

A detailed isothermal crystallization study of biobased and biodegradable isodimorphic poly (butylene succinate-ran-butylene azelate) random copolyesters (PBS-ran-PBAz) with a wide composition range has been carried out to determine nucleation kinetics, spherulitic growth rates and overall crystallization kinetics. Differential Scanning Calorimetry (DSC) and Polarized Light Optical Microscopy (PLOM) analysis show that for the PBS-rich phase, the incorporation of BAz comonomer leads to a significant increase in nucleation density and a decrease in spherulitic growth. On the contrary, for the PBAz-rich phase, an antinucleating effect of the incorporation of BS comonomer has been observed. Both effects agree with the thermodynamic analysis of the equilibrium melting point depression as a function of composition, which predicts that only a small amount of BAz comonomer is included within the PBS-rich crystals and a larger amount of comonomer is included in PBAz-rich crystals. In addition, the enthalpy of melting of 100% crystalline PBS and PBAz were determined by a different practical approach: extrapolating real time synchrotron Wide Angle X-ray Scattering (WAXS) isothermal crystallization data and isothermal DSC data.I.A. gratefully acknowledges the award of a PhD fellowship by UPV/EHU. J.M. acknowledges support from the Provincial Council of Gipuzkoa under the program Fellow Gipuzkoa. R.M and Ph.D. thank the Belgian Federal Government Office of Science Policy (SSTC- PAI 6/27) for general support and are much indebted to both Wallonia and the European Commission “FSE and FEDER” for financial support in the frame of SYNOPLISS-POLYTISS and LCFM-BIOMAT projects. The POLYMAT/UPV/EHU team would like to acknowledge funding from MINECO through project: MAT2017-83014-C2-1-P, and from ALBA synchrotron facility through granted proposal 2018022683. Finally, we also acknowledge funding by the European Union′s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 778092