Comparing non-isothermal melt and cold crystallization behavior and kinetics of poly(ethylene 2,5-furandicarboxylate-co-ethylene terephthalate) copolyesters

The objective of the present work was to compare the non-isothermal melt and cold crystallization behavior and kinetics of poly(ethylene 2,5-furandicarboxylate-co-ethylene terephthalate) (PEFT) copolyesters. First, the non-isothermal melt and cold crystallization behavior of PET and PEFT copolyesters were studied at a fixed cooling and heating rate with differential scanning calorimeter (DSC). Second, the non-isothermal melt and cold crystallization behavior of PET, PEFT5% and PEFT10% were studied at various cooling and heating rates, respectively. Third, the non-isothermal melt and cold crystallization kinetics of PET, PEFT5% and PEFT10% were analyzed with the crystallization half-time and Mo equation. It was found that with the increase in the FDCA content, the melt crystallization of PEFT gets gradually more difficult, and PEFT5%, PEFT10% and PEFT15% show cold crystallization behavior. The non-isothermal melt and cold crystallization rate of PET, PEFT5% and PEFT10% increases with the cooling and heating rate, respectively. At the same rate of cooling and heating, the cold crystallization rate is much larger than the melt crystallization rate. The copolymerization of FDCA units significantly hinders the melt crystallization rate of PEFT, while its effect on cold crystallization rate is not so prominent. The melt crystallization in PET during quenching significantly hinders its cold crystallization, thus leading to unexpectedly the cold crystallization rate of PEFT5% larger than that of PET. Based on this study, cold crystallization can be adapted as a feasible means for more efficiently adjusting the crystallization of PEFT copolyesters in practical processing.