Crystallization-Controlled Structure and Thermal Properties of Biobased Poly(Ethylene2,5-Furandicarboxylate)

Crystallization-controlled structure and thermal properties of biobased poly(ethylene 2,5-furandicarboxylate) (PEF) were studied. The cold-crystallization temperature controlled the structure and thermal properties of the biobased PEF. The melting was complex and evidenced the presence of a significant fraction of less-stable crystals with a low melting temperature that linearly increased with T_c, which formed already during the early stages of crystallization, together with those melting at a higher temperature. Low T_c resulted in the α'-phase formation, less crystallinity, and greater content of the rigid amorphous phase. At high T_c, the α-phase formed, higher crystallinity developed, the rigid amorphous phase content was lower, and the melting temperature of the less-stable crystals was higher; however, slight polymer degradation could have occurred. The applied thermal treatment altered the thermal behavior of PEF by shifting the melting of the less stable crystals to a significantly higher temperature. SEM examination revealed a spherulitic morphology. A lamellar order was evidenced with an average long period and small average lamella thickness, the latter about 3-3.5 nm, only slightly increasing with T_c.