Characterization and mechanical properties of prepolymer and polyurethane block copolymer with a shape memory effect |
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Authors: | Email author" target="_blank">Jae?Whan?ChoEmail author Yong?Chae?Jung Sun?Hwa?Lee Byoung?Chul?Chun Yong-Chan?Chung |
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Institution: | (1) Department of Textile Engineering, Konkuk University, 143-701 Seoul, Korea;(2) Department of Polymer Engineering, The University of Suwon, 445-743 Kyunggi, Korea;(3) Department of Chemistry, The University of Suwon, 445-743 Kyunggi, Korea |
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Abstract: | The prepolymer and the final polyurethane (PU) block copolymer were synthesized by reacting 4,4-methylene bis(phenylisocyanate)
with poly(tetramethylene glycol) and the prepolymer with 1,4-butanediol as a chain extender, respectively, to investigate
the relation between phase separation and it’s resulting properties. According to FT-IR data, the phase separation of hard
and soft segments in the prepolymer and the PU block copolymer grew bigger by increasing the hard segment content, and the
PU showed more dominant phase separation than the prepolymer. The heat of fusion due to soft segments decreased in both the
prepolymer and the PU by increasing the hard segment content, whereas the heat of fusion due to hard segments increased in
the PU did not appear in the prepolymers. The breaking stress and modulus of the prepolymer increased by increasing the hard
segment content, and the elongation at break decreased gradually, and the PU showed the highest breaking stress and modulus
at 58 % hard segment content. However, the best shape recovery of the PU was obtained at 47 % hard segment content due to
the existence of proper interaction among the hard segments for shape memory effect. Consequently, the mechanical properties
and shape memory effect of the PU were influenced by the degree of phase separation, depending on the incorporation of chain
extender as well as the hard segment content. |
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Keywords: | Polyurethane Phase separation Mechanical properties Shape memory |
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