Structure and stress relaxation in shape memory polymers (SMPs), which show the time-dependent response to temperature and mechanical loading, respectively, are usually thought to be the primary mechanisms of shape memory effects (SMEs). However, the synergistic effect of structure and stress relaxation has not been well investigated. What's more, convenient and economic manufacturing and structural customization of SMPs can be easily achieved by four-dimensional (4D) printing technology. Thus, in this paper, we comprehensively analyze the working mechanisms of synergistic-relaxation effects in both traditional and 4D-printed SMPs using theoretical calculations and experimental confirmation. Specifically, the calculations are based on the thermo-mechanical and electro-thermo-mechanical models, and multiple sets of experimental data are used to verify the model results. The model results agree well with the experimental data and demonstrate that synergistic-relaxation mechanisms play an important role in thermo-mechanical behaviors.

中文翻译：

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深入了解非晶聚合物中的“协同-松弛效应”：热力学建模、多物理场仿真和 4D 打印中的应用


形状记忆聚合物 （SMP） 中的结构和应力松弛分别显示出对温度和机械载荷的时间依赖性响应，通常被认为是形状记忆效应 （SME） 的主要机制。然而，结构和应力松弛的协同效应尚未得到很好的研究。此外，通过四维 （4D） 打印技术可以轻松实现 SMP 的方便和经济的制造和结构定制。因此，在本文中，我们使用理论计算和实验证实全面分析了传统和 4D 打印 SMP 中协同松弛效应的工作机制。具体来说，计算基于热机械和电热机械模型，并使用多组实验数据来验证模型结果。模型结果与实验数据吻合较好，并表明协同弛豫机制在热机械行为中起着重要作用。