Excellent memory performance of poly (1,6-hexanediol adipate) based shape memory polyurethane filament over a range of thermo-mechanical parameters

Abstract

Shape memory filaments have significant implications in smart wearable textiles, biomedical sutures, and additive manufacturing. However, the deterioration of shape memory performance over a range of temperature and strain limits their use in many high-end applications. This investigation reports the shape memory properties of segmented polyurethane filament and its detailed chemical and thermo-mechanical characterization. Shape memory polyurethane (SMPU) based on poly(1,6-hexanediol adipate) (PHA), 4,4′-diphenylmethane diisocyanate (MDI), and 1,4-butanediol (BDO) shows the transition temperature near body temperature. Hard segment and soft segment content in SMPU is 28.5% and 71.5% by weight. SMPU filament exhibited excellent shape recovery (~ 98%) and higher shape fixity (~ 80%) at a strain of 20%, 40%, and 60% and temperature of 30 ℃ and 50 ℃. Results have been supported by thermal and X-ray analysis. The cause of high fixity has been discussed in detail. Experimental results indicated higher crystallization and melting enthalpy. The cyclic test of SMPU filament showed almost complete shape recovery with no change in shape fixity under different thermo-mechanical conditions.