Effect of glycerol cross-linking and hard segment content on the shape memory property of polyurethane block copolymer

Effect of glycerol cross-linking and hard segment content on the shape memory property of polyurethane block copolymer is comprehensively investigated. Phase separation of hard and soft segment is dependent on glycerol cross-linking and hard segment content as judged from FT-IR and DSC data. Hydrogen bonding and dipole-dipole interaction between hard segments provides strong interaction between copolymer chains in addition to chemical cross-linking by glycerol. As the hard segment content increases, the copolymer shows better tensile mechanical properties and higher melting temperature of soft segment (T-m). Effect of glycerol cross-linking on mechanical properties and T-m of soft segment is low compared to hard segment effect. Although XRD peak at 2 theta = 19.5 degrees is observed, clear difference between the copolymers with various hard segment and cross-linking content is not observed. Significant increase in shape recovery rate in the case of 30 wt% hard segment copolymer is observed after glycerol cross-linking. The drastic change of the properties of polyurethane block copolymer is discussed in the point of copolymer chain interaction.