ポリウレタン系形状記憶ポリマーの形状回復および二次賦形に及ぼすひずみ保持条件の影響

抄録

By applying strain at high temperature to polyurethane-shape memory polymer film, followed by holding the strain under various thermomechanical conditions, the behavior of strain recovery by heating after these processes was investigated. In the experiments, the influence of the strain-holding conditions on shape recovery and secondary-shape forming was discussed. The results obtained are summarized as follows. (1) If strain is held at high temperature for short time, irrecoverable strain starts to appear at the holding time t_h =0.5 h and strain is not recovered at all at t_h =8 h in the care of holding temperature T_h = T_g + 20 K. In the case of T_h = T_g + 10 K, irrecoverable strain appears for short holding time if initial strain is large and the rate of secondary-shape forming S is 42% at t_h =8 h. (2) If initial strain of 50% is held at low temperature for long time, strain becomes not to be recovered and S is 93% at t_h=12 h in the care of T_h = T_g + 10 K. In the care of T_h = T_g, the increasing rate of S increases if t_h becomes longer than 40 h. If T_h is lower than T_g - 10 K for t_h=72 h, strain is recovered perfectly by heating and secondary-shape forming does not appear.