Isothermal crystallization and structural characterization of poly(ethylene-2,5-furanoate)

Biaxial Orientation of Poly(ethylene 2,5‐furandicarboxylate): An Explorative Study

“…This difference can be explained by the lower entanglement density in PEF. Indeed, Kriegel et al and Stoclet et al have reported a molecular weight between entanglements of 2900–3750 and 3500 g mol −1 , respectively, for PEF that they both compared to a literature value of 1450 g mol −1 for PET . A single chain with a higher distance between two entanglements would require more deformation until fully oriented.…”

“…As a consequence this interpretation yields a significant contribution of cold crystallization for all PET and PEF samples, even though one could argue that mainly the samples stretched at 95 and 105 °C to ASR 4 × 4 have the classical shape of a cold crystallization peak. The main target of the evaluation is however the estimation of the melting enthalpy of the strain‐induced crystals Δ H melt(SIC) and subsequently the total percentage of SIC (%SIC), which can be calculated from the integrated DSC peaks via the following equationswhere Δ H melt(total) is the total melting enthalpy, Δ H cc is the cold crystallization enthalpy as described previously and Δ H° melt the equilibrium melting enthalpy taken at 140 J g −1 for both PEF and PET …”

“…The development of strain‐induced crystallinity in PEF would merit a more direct study by wide angle X‐ray diffraction to provide insight in the crystal structure formed. Indeed, for isotropic crystalline PEF there have been suggestions for the existence of an α polymorph, a less perfect α' polymorph, and a β polymorph, while two crystal structures have been proposed for PEF via uniaxial hot drawing . For specimens prepared via biaxial orientation, combined or new structures could be present.…”

“…For example, Burgess et al have attributed the lower gas permeability in PEF compared to PET to a reduced chain mobility, which in turn is associated with the lower bond angle of the carboxyl groups on the furan ring that constrains its rotation compared to the linear arrangement on the benzene ring . They have predicted that this chain mobility is the cause of a slower crystal growth rate of PEF compared to PET via its effect on chain diffusion, which was later demonstrated by several authors . Papageorgiou et al and various published work by their group have highlighted that FDCA‐based polyesters in general display reduced crystallization rates and melt points compared to their TPA‐ and 2,6‐Naphthalenedicarboxylic Acid (NDCA)‐based counterparts, while the glass transition temperatures typically fall in‐between .…”

Biobased poly(ethylene furanoate-co-ethylene succinate) copolyesters: solid state structure, melting point depression and biodegradability

“…For PEF it was found that appearance of multiple melting depends on the crystallization temperature 56,68,69 . Sbirrazzuoli and coworkers have reported that the multiple melting of PEF occurs due to recrystallization during heating and not due to the different distributions of lamellar thickness of the material 70 .…”