Current-Dependent Dynamics of Bidirectional Self-Folding for Multi-Layer Polymers Using Local Resistive Heating
Current-Dependent Dynamics of Bidirectional Self-Folding for Multi-Layer Polymers Using Local Resistive Heating
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DOI：
10.1115/1.4049588
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发表时间：
2021-07
影响因子：
1.2
通讯作者：
Moataz Elsisy;Evan Poska;Moataz Abdulhafez;M. Bedewy
中科院分区：
文献类型：
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作者：
Moataz Elsisy;Evan Poska;Moataz Abdulhafez;M. Bedewy
本文的目的是表征的动力学和方向的预应变聚苯乙烯（PSPS）和非预应变的苯乙烯（PEPS），这是由于局部收缩使用一个新的过程中的定向自折叠的聚合物片材的基础上，在与片材接触的连续加热带的自折叠。横跨该形状记忆聚合物（SMP）片的厚度的温度梯度引起沿与加热带接触的线沿着折叠。改变电流会改变折叠的程度和局部材料流动的范围。该方法可用于创建实际的三维（3D）结构。将PSPS片和聚苯乙烯片切成10 × 20 mm的样品，并将其折叠角与时间作图，如从原位摄像获得的。此外，使用聚酰亚胺胶带（Kapton）进行了研究，以控制自折叠的方向。结果表明，无论加热带在哪一侧，也无论重力是否与折叠方向相反，折叠都发生在样本相对于胶带的相反侧。结果进行了定量解释，使用粘弹性有限元模型能够描述双向褶皱所产生的粘弹性松弛和应变之间的相互作用，聚苯乙烯和聚酰亚胺的不匹配。考虑到折叠时间的可调性和局部材料流动的程度，连续加热辅助折叠是通过折纸工程制造复杂的3D轻质结构的一种有前途的方法。
The purpose of this paper is to characterize the dynamics and direction of self-folding of pre-strained polystyrene (PSPS) and non-pre-strained styrene (NPS), which results from local shrinkage using a new process of directed self-folding of polymer sheets based on a resistively heated ribbon that is in contact with the sheets. A temperature gradient across the thickness of this shape memory polymer (SMP) sheet induces folding along the line of contact with the heating ribbon. Varying the electric current changes the degree of folding and the extent of local material flow. This method can be used to create practical three-dimensional (3D) structures. Sheets of PSPS and NPS were cut to 10 × 20 mm samples, and their folding angles were plotted with respect to time, as obtained from in situ videography. In addition, the use of polyimide tape (Kapton) was investigated for controlling the direction of self-folding. Results show that folding happens on the opposite side of the sample with respect to the tape, regardless of which side the heating ribbon is on, or whether gravity is opposing the folding direction. The results are quantitatively explained using a viscoelastic finite element model capable of describing bidirectional folds arising from the interplay between viscoelastic relaxation and strain mismatch between polystyrene and polyimide. Given the tunability of fold times and the extent of local material flow, resistive-heat-assisted folding is a promising approach for manufacturing complex 3D lightweight structures by origami engineering.