Strain induced crystallization in biobased Poly(ethylene 2,5-furandicarboxylate) (PEF); conditions for appearance and microstructure analysis

Strain-induced crystallization of poly(ethylene 2,5-furandicarboxylate). Mechanical and crystallographic analysis

“…However, SIC cannot be induced for easily accessible natural draw ratio (NDR) at any strain-rate. From experience [31,35], we know that sets of temperature and strain-rate that are relevant are those for which the material exhibits a rubber-like behaviour remaining close to α transition. So as to design the experimental campaign at large deformations, this combined dependency of the behaviour with the temperature and with the strain-rate has to be investigated.…”

“…Because of its relative novelty as well as its rarity, few studies deal with the mechanical behaviour and with SIC of PEF under uni-axial stretching [29][30][31] or under bi-axial stretching [32]. Considering the "state of the art", it appears that PEF should exhibit SIC as PET does, but a simple transposition of stretching conditions cannot be successful.…”

“…Stretching temperature and strain rate must be adjusted to PEF to account for specific glass transition temperature and chain dynamics. Based on the assumption that stretching of an amorphous polymer is efficient when the material is in its rubber-like state, Menager et al [31] successively used an approach based on the time (or frequency)/temperature superposition principle to select relevant stretching conditions for PEF (temperature and strain rate). It was then demonstrated that a range for draw ability of PEF could be defined in terms of equivalent strain rate at a reference temperature deduced from linear visco-elastic analysis, as for PET and other materials (for more information see Refs.…”

“…Upon stretching above its glass transition, and for appropriate temperature and strain rate conditions, PEF strain-induced crystallization has been proven [29][30][31][32]. Nevertheless, none of the previous studies allowed to unambiguously relate local mechanical loading to local microstructure, due to the use of engineering data.…”

“…To avoid any ambiguity and complete previous study [31], specific efforts are devoted to the control of both local loading path and local thermo-mechanical history. Doing this, draw ability and correlation between drawing conditions and final microstructure will be addressed.…”