Two-way reversible shape memory effects in a free-standing polymer composite
Two-way reversible shape memory effects in a free-standing polymer composite
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DOI：
10.1088/0964-1726/20/6/065010
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发表时间：
2011-06-01
影响因子：
4.1
通讯作者：
Qi, H. Jerry
中科院分区：
文献类型：
--
作者：
Westbrook, Kristofer K.;Mather, Patrick T.;Qi, H. Jerry
形状记忆聚合物（SMP）由于其易于制造和高度可定制的热机械性能而吸引了大量的研究工作。SMP可以被暂时编程并固定在非平衡形状中，并且能够在暴露于刺激时恢复原始未变形的形状，最常见的是温度。大多数SMP表现出单向形状记忆（1W-SM）效应，因为一个编程步骤只能产生一个形状记忆周期;额外的形状记忆周期需要额外的编程步骤。最近，一位作者（Mather）证明了一种新的SMP，该SMP显示了1W-SM和双向形状记忆（2W-SM）效应。然而，为了实现双向致动，这种SMP依赖于恒定的外部施加的负载。在本文中，SMP复合材料，其中预拉伸2W-SMP嵌入在弹性体基体的开发。该复合材料在不需要恒定外部负载的情况下响应于温度变化而展示2W-SM效应。实现了类似于致动器长度的10%的横向致动。循环测试表明，横向驱动稳定后的初始训练周期，并显示四个周期后没有显着下降。一个简单的分析模型，考虑编程应力和致动器的尺寸，并示出同意以及致动器的横向位移。该模型还预测，当使用较大的2W-SMP预拉伸时，可以实现较大的致动。该方案可以促进新型形状记忆复合材料在微米和纳米尺度上的设计，以满足不同的应用需求。
Shape memory polymers (SMPs) have attracted significant research efforts due to their ease in manufacturing and highly tailorable thermomechanical properties. SMPs can be temporarily programmed and fixed in a nonequilibrium shape and are capable of recovering the original undeformed shape upon exposure to a stimulus, the most common being temperature. Most SMPs exhibit a one-way shape memory (1W-SM) effect since one programming step can only yield one shape memory cycle; an additional shape memory cycle requires an extra programming step. Recently, a novel SMP that demonstrates both 1W-SM and two-way shape memory (2W-SM) effects was demonstrated by one of the authors (Mather). However, to achieve two-way actuation this SMP relies on a constant externally applied load. In this paper, an SMP composite where a pre-stretched 2W-SMP is embedded in an elastomeric matrix is developed. This composite demonstrates 2W-SM effects in response to changes in temperature without the requirement of a constant external load. A transversal actuation of similar to 10% of actuator length is achieved. Cyclic tests show that the transversal actuation stabilizes after an initial training cycle and shows no significant decreases after four cycles. A simple analytic model considering the programming stress and actuator dimensions is presented and shown to agree well with the transverse displacement of the actuator. The model also predicts that larger actuation can be achieved when larger pre-stretch of 2W-SMP is used. The scheme used for this polymer composite can promote the design of new shape memory composites at micro-and nano-length scales to meet different application requirements.