Crystallization Rate of Soft Segment on Shape Memory Effect in Shape Memory Polyurethane Ionomer

摘要

To illustrate the effect of crystallization rate of soft segment on shape memory effect in shape memory polyurethane (SMPU) ionomer, SMPU ionomers having ionic group within hard segments were synthesized. Isothermal crystallization kinetic method was used to analyze the effect of ionic groups within hard segments on crystallization of soft segment. Thermal cyclic tensile testing was conducted to investigate the shape memory effect. It was found that the ionic group in hard segments slows down crystallization of soft segment; when physical cross link is strong enough, the crystallization rate would be a predominant factor determining the shape fixity ratio after various cooling time; when physical cross link is weakening, the influence of crystallization rate is much less for cooling time dependence of fixity.