Poly(ethylene 2,5-furandicarboxylate) (PEF) is an emergent biobased polyester whose chemical structure is analogous to poly(ethylene terephthalate). Pilot-scale PEF is synthesized through the direct esterifi cation process from 2,5-furandicarboxylic acid and bio-ethylene glycol. Wideangle X-ray diffraction (WAXD) measurements reveal similar crystallinities and unit cell structures for melt-crystallized and glass-crystallized samples. The non-isothermal crystallization of PEF sample is investigated by means of DSC experiments both from the glass and the melt. The temperature dependence of the effective activation energy of the growth rate is obtained from these data, and the results show that the glass and early stage of the melt crystallization share common dynamics. Hoffman-Lauritzen parameters and the temperature at maximum crystallization rate are evaluated. It is found that the melt-crystallization kinetics undergo a transition from regime I to II; however, the crystal growth rate from the melt shows an atypical depression at T < 171 °C compared with the predicted Hoffman-Lauritzen theory.

Poly(ethylene 2,5-furandicarboxylate) (PEF) is a polyester from ethylene glycol and 2,5-Furandicarboxylic acid which has gained increasing interest due to its excellent properties compared to chemically similar PET. This paper presents an estimation of the crystallization enthalpy, the crystalline and amorphous density and the crystallization kinetics of PEF. Using Avrami and the Hoffman-Lauritzen theory, HoffmanLauritzen parameters are proposed that relate crystal growth rate of catalyst-free PEF to temperature and molecular weight. Characteristic is a higher activation energy for chain diffusion (U*) for PEF compared PET, which can be attributed to more restricted chain conformational changes. Finally, the crystallization rate of PEF is shown to be significantly affected by catalyst type.

The glass transition of poly(ethylene 2,5-furandicarboxylate) (PEF), an emergent bio-based polyester, was investigated in comparison to one of its chemical analogues: poly(ethylene terephthalate) (PET). These investigations were conducted at different crystallinities by means of stochastic modulated differential scanning calorimetry (stochastic TMDSC) and dynamic mechanical analysis (DMA). Amorphous PEF presents a higher ΔCp at the glass transition and a broader relaxation spectrum attributed to a higher free volume. The higher Tg of PEF is then purely related to segmental mobility and specific interactions in PEF. The length of cooperative rearranging regions (CRR) was similar for both materials. Additionally, the variations of the effective activation energy E of PEF and PET at glass transitions were determined by isoconversional kinetic analysis. The rate of decrease in E was similar for the two amorphous polyesters. Upon crystallization, the glass transition of PEF is broadened but its temperature range is not increased as with PET. The creation of the rigid amorphous fraction (RAF) with crystallinity is lower in PEF than in PET. The difference in free volume also explains the lower coupling between the crystalline phase and the amorphous phase in PEF.

The biaxial orientation behavior of poly(ethylene 2,5‐furandicarboxylate) (PEF) is studied in comparison to poly(ethylene terephthalate) (PET). PEF is a polyester that can be produced through similar steps as PET but using 100% biobased 2,5‐furandicarboxylic acid instead of terephthalic acid. This work highlights the stress–strain behavior of PEF during biaxial orientation at various temperatures. Strain hardening and strain‐induced crystallization in the oriented PEF samples generally appeared at higher stretch ratios for PEF than for PET at comparable molecular weight, while somewhat lower degrees of crystallinity are reached in PEF. Shrinkage in oriented PEF is found to be on par with PET in the region of the glass transition. Higher modulus and improved barrier properties, compared to PET, are found in the oriented materials when sufficiently high stretch ratios are applied in biaxial orientation.

Front Cover: Poly(ethylene 2,5‐furandicarboxylate) (PEF), an emergent biobased polyester, is produced through direct esterification and polycondensation of purified 2,5‐furan‐dicarboxylic acid (FDCA), obtained from sugar derived from 1st or 2nd generation feedstocks. In‐depth understanding and control over the crystallization process from the melt, as well as from the glass, are of major importance from both the academic standpoint and with regard to obtaining final manufactured products, such as bottles or T‐shirts, with desired properties, since fast crystallization from the glassy state is desired for solid‐state polycondensation (SSP) and industrial reprocessing, whereas slow crystallization from the melt is desired for injection stretch blow molding of preforms for bottle blowing. Further details can be found in the article by A. Codou, N. Guigo, J. van Berke, E. de Jong, and N. Sbirrazzuoli* on page 2065.

Solution and melt viscosity relations to molecular weight were obtained for bio-based poly­(ethylene 2,5-furandicarboxylate) (PEF) in comparison to poly­(ethylene terephthalate) (PET). Furthermore, the rate dependent glassy state tensile properties were explored at varying molecular weights, showing ductile behavior for high molecular weight PEF at low rates. The unperturbed chain dimensions of PEF indicate similar conformational freedom to PET but lower chain packing due to the shorter bond length of 2,5-furandicarboxylic acid (FDCA), inducing a lower entanglement density as corroborated by plateau moduli measurements. The high temperature and shear rate dependence of the melt viscosity as well as the high strain rate dependence of the glassy state yield stress can be explained by this lower entanglement density, although the glassy state may furthermore be subject to chain mobility restrictions.

No abstract

Novel clay-based PEF nanocomposites with higher thermal stabilities than pure PEF both under inert (+20 °C) and oxidative atmosphere (+30 °C).