Crystallization and melting behavior of three biodegradable poly(alkylene succinates). A comparative study

Polyesters based on succinic acid and respective aliphatic diols, with 2-4 methylene groups were synthesized by melt polycondensation. Crystallization and melting behaviour of samples having the same molecular weight were studied. The odd-even effect was observed for the melting temperatures of these polymers. Poly(propylene succinate) exhibited the slower crystallization rates and lower degree of crystallinity, among these polyesters. In contrast poly(butylene succinate) showed the faster crystallization rates and higher degree of crystallinity. Multiple melting of the isothermally crystallized samples was attributed to partial melting re-crystallization and re-melting, as was revealed by MTDSC measurements and observations at fast DSC heating scans. The equilibrium melting points were found to be 114, 133.5 and 58 °C for PESu, PBSu and PPSu respectively. Also, the corresponding values for enthalpy of fusion were 180, 210 and 140 J/g. Spherulitic growth rates were analysed and the regime transition of PESu and PBSu was studied.