Mechanical reinforcement and memory effect of strain-induced soft segment crystals in thermoplastic polyurethane-urea elastomers

An amorphous poly(urethane-urea) copolymer composed of 70 wt% poly(ethylene oxide) (PEO) soft segments (SS) (Mw = 2000 g mol?1) and 30 cycloaliphatic hard (HS) was subjected to in-situ X-Rays during tensile deformation. Mechanical hardening at room temperature attributed strain induced crystallization (SIC) the PEO SS through multiplication aligned crystallites. The permanent nature these crystals after stress removal indicates a certain mechanical stability, which we related here concomitant effect superstraining crystallites HS reorganization upon This is in marked contrast previous studies reported crystalline phase be temporary unloading. A manifestation such enhanced stability memory evidenced by an increased crystallizability incremental cyclic loading. These results offer way (i) tune properties TPUs via formation mechanically stable pre-oriented (ii) thermally/water activated shape (shape fixity, kinetics recovery).