Synthesis of thermoplastic polyurethane and its physical and shape memory properties

In this article, thermoplastic polyurethane (PU) with a shape memory property was synthesized. First, the PU prepolymer was prepared by reacting poly(tetramethylene glycol) with 4,4'-diphenylmethane diisocyanate, then extended with various extenders such as linear aliphatic 1,4-butanediol, benzoyl-type 4,4-bis(4-hydroxyhexoxy)-isopropylane and naphthalate-type bis(2-phenoxyethanol)-sulfone or naphthoxy diethanol. The experimental results showed that the tensile strength, elongation at break, and initial modulus at 300% of these copolymer films were in the range of 31-64 Mpa, 42%-614%, and 8.26-11.5 MPa, respectively. Thermal analysis showed that the glass-transition temperature of these copolymers was in the range of -73 degrees C to -50C for the soft segment (T(g)s) and 70 degrees C-106 degrees C for the hard segment (T(g)h) and that the melting point was in the range of 14.6 degrees C-24.2 degrees C for the soft segment and 198 degrees C-206 degrees C for the hard segment. The extender with a benzoyl or naphthalate group was better able to promote its shape memory property than was the regular polyurethane. (c) 2006 Wiley Periodicals, Inc.