Excellent memory performance of poly (1,6-hexanediol adipate) based shape memory polyurethane filament over a range of t
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ORIGINAL PAPER
Excellent memory performance of poly (1,6‑hexanediol adipate) based shape memory polyurethane filament over a range of thermo‑mechanical parameters Priyanka Gupta1 · Hema Garg2 · Jayashree Mohanty2 · Bipin Kumar1 Received: 13 July 2020 / Accepted: 6 November 2020 © The Polymer Society, Taipei 2020
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(1,6hexanediol 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. Keywords Shape memory · Polyurethane · Filament · poly(1,6-hexanediol adipate) · Stress relaxation · Cyclic behaviour
Introduction In the last two decades, the development and applications of shape memory polymers (SMP) have been explored for various fields including medical, civil, transport, aviation, textile, robotics, etc. [1–8]. They possess a unique property, shape memory, through which their permanent shape can be fixed to a temporary shape through a suitable thermomechanical process; this temporary shape remains stable at the normal condition for usage, and it can be reverted back to the original shape in presence of an external stimuli like heat [9], light [10], water [11], electricity [12], etc. This shape fixing and shape recovery of SMP is achieved due to the presence of two separate phases, soft segment (reversible phase) and hard segment (fixed phase) [13, 14]. The hard * Bipin Kumar [email protected] 1
Department of Textile and Fibre Engineering, Indian Institute of Technology, Delhi, New Delhi‑110016, India
School of Interdisciplinary Research, Indian Institute of Technology, Delhi, New Delhi‑110016, India
2
segment shows higher thermal transition temperature, assists the polymer to memorize the original shape, while the soft segment exhibits a lower thermal transition temperature, aids in the fixation of temporarily deformed shape [15, 16]. Several polymer networks based on polynorbornene, poly(transisoprene), styrene-butadiene copolymers, and polyurethane elastomers have been studied to ach
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