Novel biobased high toughness PBAT/PEF blends: morphology, thermal properties, crystal structures and mechanical properties
Poly(ethylene 2,5-furandicarboxylate) (PEF) is a fully biobased rigid polyester characterized by a high tensile modulus and strength. Poly(butylene adipate-co-terephthalate) (PBAT) is a petroleum-based flexible polyester. In this study, a series of PBAT/PEF blends with 1–50 wt% PEF contents were directly prepared by a melt blending method. The morphologies, thermal properties, crystal structures and mechanical properties of the blends were investigated. The SEM results showed that PEF was uniformly dispersed in the PBAT phase, which indicated that PBAT and PEF had good compatibility. Also, the PBAT/PEF blends displayed typical sea-island morphology structures, in which PBAT acted as a continuous phase and PEF was a discrete phase. The ATR-FTIR results showed that there was no interfacial bonding between PBAT and PEF in the blends. The TGA results displayed that thermal stability slightly deteriorated from 385.5 °C to 371.7 °C with increasing PEF content. The DSC results indicated that the blends had two Tgs, corresponding to those of PBAT and PEF. The WAXD results showed that PEF did not change the crystal structure of PBAT and was amorphous in the blends. All the PBAT/PEF blends exhibited toughness behavior, with high elongation at break and impact strength. In particular, when the content of PEF was 1%, 3%, 5% or 7%, the blends showed excellent elongations at break, which were higher than those of PBAT (1005.8 ± 114.2%) and PEF (6.0 ± 0.4%). When the content of PEF was 40%, the impact toughness of the blends was 91.0 ± 8.7 kJ m−2, which was 4.5 times that of PBAT and 13 times that of PEF. These findings have important implications for the application of PEF and the design of blend materials with high toughness.