Abstract: The methods of DSC, IR, WAXD, PLM and SALS were employed to investigate the differences between the crystallization bahavior of hard segments in the polyester-based aliphatic and aromatic polyurethanes. It is found that the rate of phase separation of aliPhatic polyurethane is higher and the hydrogen bonding is formed mainly between the hard segments, which promotes the crytallizaticn of hard segments, while the rate of phase separation of aromatic polyurethane is very low. Nevertheless, the hydrogen bonding can also be formed betwcen the soft and hard segments, which hinders the crystallization of hard segments.

Key words: Polyurethane, Hard segments, CrYstallisation, Phase separation