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以三枝化低不饱和度聚环氧丙烷/聚乳酸两嵌段共聚物(POLA)为原料,甲苯二异氰酸酯(TDⅠ)交联制备可降解聚环氧丙烷/聚乳酸基聚氨酯(POLA-PU).通过对POLA共聚物序列结构的调控,制备了由高模量低断裂伸长率的脆性到低模量高断裂伸长率的韧性POLA-PU可降解形状记忆材料.由TMA测得POLA-PU的形变温度为96～153℃.POLA-PU试样在140℃的形状记忆恢复时间不超过20 s.在200%拉伸形变条件下,POLA-PU的形变固定率在65%～100%之间,形变回复率均可达100%.实验表明,形状记忆行为取决于链的交联密度,记忆效应归属于不同温度下柔性链的构象熵变化.降解实验结果表明,聚乳酸链段的引入赋予了该形状记忆材料良好的降解性能,且随着聚乳酸含量的降低而下降.
The degradable polypropylene oxide / polylactic acid based polyurethane (POLA-PU) was prepared by cross-linking tolylene diisocyanate (TDⅠ) with three branches of low unsaturation polypropylene oxide / polylactic acid diblock copolymer POLA-PU degradable shape memory materials with high modulus and low elongation at break and brittleness to low modulus and high elongation at break were prepared by adjusting the structure of POLA copolymer.The POLA- The deformation temperature of PU is 96 ~ 153 ℃ .The shape memory recovery time of POLA-PU sample is less than 20 s at 140 ℃ .The deformation fixation rate of POLA-PU is about 65% ~ 100% at 200% , The deformation recovery rate can reach 100% .Experiments show that the shape memory behavior depends on the cross-link density of the chain, and the memory effect belongs to the conformational entropy change of the flexible chain at different temperatures. The degradation experiments show that the polylactic acid segment The incorporation gives good conformability to the shape memory material and decreases with decreasing polylactic acid content.