Strain induced crystallization in biobased Poly(ethylene 2,5-furandicarboxylate) (PEF); conditions for appearance and microstructure analysis
Résumé
Poly(ethylene 2,5-furandicarboxylate) (PEF) is an emerging biobased thermoplastic polymer that may replace PET for stretching applications such as bottle blowing, thermoforming, or film extrusion. The stretch ability and strain induced microstructure in PEF have not been fully addressed in the literature despite being the key issue for industrial processing. In this study, it is demonstrated that PEF can develop an organized crystalline-like microstructure under uni-axial stretching above its glass transition and can exhibit behavior close to that of PET with drastic strain hardening and coupled sensitivities to strain rate and temperature. The time-temperature superposition principle appeared to make it possible to map stretch ability in terms of strain rate and temperature , and to develop conditions for strain-induced crystallization (SIC). The periodic microstructure of stretched PEF was highlighted by means of wide-angle X-Ray scattering and analyzed with stochastically modulated temperature DSC (TOPEM). Depending on the stretching conditions applied to PEF, different morphologies of crystals are developed. The heat capacity (ΔC P), crystalline fraction (X C), mobile amorphous fraction (X MAF), and rigid amorphous fraction (X RAF) for stretched and non-stretched PEF samples were evaluated .