Nie Danli, Yin Xianze, Cai Ziqing, Wang Jintao
College of Materials Science and Engineering, Wuhan Textile University, Wuhan 430200, China.
College of Materials Science and Engineering, Wuhan Institute of Technology, Wuhan 430205, China.
Polymers (Basel). 2022 Apr 12;14(8):1569. doi: 10.3390/polym14081569.
The opportunity for the preparation of high-performance shape memory materials was brought about by the excellent mechanical properties of poly(lactic acid) (PLA). As the effect of crystallization on shape memory was still unclear, this brings constraints to the high-performance design of PLA. The PLA plates with different aggregation structure were prepared by three kinds of molding methods in this paper. The PLA plates were pre-stretched with a series of different strains above glass transition temperature (i.e., 70 °C). The recovery stress and ratio of the material were measured above stretching temperature (i.e., 80 °C). Prolonging of annealing time resulted in more perfect crystal structure and higher crystallinity. The crystal region acted as network nodes in shape memory PLA, and crystal region structure determined the shape memory performance. Based on the experimental results, the structural evolution of network nodes in shape memory PLA was established.
聚乳酸（PLA）优异的机械性能为制备高性能形状记忆材料带来了契机。由于结晶对形状记忆的影响尚不清楚，这给PLA的高性能设计带来了限制。本文采用三种成型方法制备了具有不同聚集结构的PLA板材。在玻璃化转变温度（即70°C）以上，对PLA板材施加一系列不同的应变进行预拉伸。在拉伸温度（即80°C）以上测量材料的回复应力和回复率。退火时间的延长导致晶体结构更完善，结晶度更高。在形状记忆PLA中，晶区充当网络节点，晶区结构决定形状记忆性能。基于实验结果，建立了形状记忆PLA中网络节点的结构演变规律。
