Soft Segment Engineering of Bio-Based Poly(propylene 2,5- furandicarboxylate) for Enhanced Toughness and Spinnability

Furan-based polyesters are attractive biobased alternatives to petroleum-derived materials, but their practical use is limited by intrinsic brittleness and slow crystallization. In this study, poly(tetramethylene ether) glycol (PTMEG) was incorporated into poly(propylene 2,5-furandicarboxylate) (PPF) to balance rigidity, toughness, and spinnability. Structural characterization confirmed successful copolymer formation, while thermal analysis revealed that PTMEG enhances chain mobility—dropping T _g from 62.26°C to 2.94°C—without sacrificing thermal robustness (T _d5% > 350°C). The copolyesters exhibited a dramatic brittle-to-ductile transition; notably, PPF-20PTMEG achieved an optimal balance with 544.05% elongation and 26.68 MPa tensile strength, while impact strength increased from 0.76 to 61.90 kJ/m². Although PTMEG lowered the cold-crystallization temperature from 109.0°C to 59.8°C, excessive loading (above 30 wt%) impaired melt-spinnability and fiber surface integrity. These findings establish 20 wt% PTMEG as the ideal composition window for high-performance biobased furan polyester elastomers and fibers.