Miscibility and shape memory effect of thermoplastic polyurethane blends with phenoxy resin

Segmented thermoplastic polyurethane (TPU) with poly(caprolactone) (PCL) based soft segment and hexamethylene diisocyanate (HDI)/1,4-butane diol (BD)/4,4′-dihydroxy biphenyl (DHBP) based hard segment was blended with phenoxy resin to examine miscibility and shape memory effect. The PCL segment and phenoxy resin made single miscible domain with single glass transition temperature (Tg) which lied between those of PCL segment and phenoxy resin. In the shape memory effect, utilizing this miscible domain as a reversible phase and utilizing phase separated hard segment domain as a fixed structure memorizing the original shape, hysteresis was reduced as the content of hard segment was increased in the blend and the block length of TPU was decreased.