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.
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.
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.
This paper presents
an investigation into the behavior and performance
of blends of Nylon 6 (PA6), polypropylene (PP), and poly(lactic acid)
(PLA), compatibilized with maleic anhydride-grafted PP (PP-
g
-MA). The mechanical performance of ternary PA6/PP/PLA
blends was superior to that of binary PA6/PP blends because of the
addition of PLA. Through blending with PLA, the tensile and flexural
strength and modulus were enhanced, maintaining performance similar
to that of neat PA6. Tensile performance was further enhanced through
reactive compatibilization of the blends with PP-
g
-MA due to the improved homogeneity of the materials. Impact behavior
of the blends was found to be highly dependent on morphology, and
the toughening behavior was observed at certain blending ratios. In
PA6/PP blends, fractionated crystallization behavior was investigated
through differential scanning calorimetry, in which both PA6 and PP
droplets were crystallized at supercooled states. This effect was
highly influenced by the presence of the compatibilizing agent and
its effect on the morphology of the dispersed phase. As the droplet
size of the dispersed phase was decreased to submicron levels, the
efficiency of heterogeneous nucleation was limited. Crystallization
of PLA in the blend was poor, but PP-
g
-MA was found
to have an impact on its rate of crystallization.
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