变形取向对高聚物力学和形状记忆性能的影响研究

Shape memory polymers (SMPs), as novel smart materials, have shown strong potential applications in industrial and biomedical areas. Compared with the traditional method of obtaining the temporary shape at high temperatures, the strategy of programming SMPs at lower temperatures can save energy and time. However, most of the current research on SMPs, programmed at low temperatures, is limited to moderate strain. Meanwhile, due to the nonequilibrium glassy state, the polymer structure continuously evolves to the equilibrium state at low temperatures, known as physical aging effect, which is not incorporated in most of the current research on SMPs. In this project we plan to develop a constitutive model to investigate the influence of large deformation at low temperatures and physical aging on mechanical properties and shape memory behaviors of amorphous polymers. A series of experiments will also be performed to characterize the mechanical and shape memory properties. The experimental results will be used to verify and improve the model. Thus, this project will combine the experimental and modeling approaches to understand the influence of deformation temperature, strain rate，deformation orientation and physical aging on thermomechanical properties and shape memory performance of amorphous polymers. The results will enhance the knowledge of amorphous polymers and advance the applications of SMPs.

形状记忆高分子作为一种新型智能材料，在工业和生物医学方面都有着非常广阔的应用前景。相对于传统的在高温形成临时形状的方法，低温变形形成临时形状的做法能节省大量的能源和时间。但是当前对低温变形下的形状记忆功能的研究主要集中在中等应变范围。此外，高聚物在低温玻璃态，其结构处于非平衡态，力学性能会随着时间不断演化，即发生物理时效效应。目前大多数对形状高分子的研究都未包含时效效应。本项目拟建立一个三维本构模型，用以研究低温大变形和物理时效对高分子力学性质和形状记忆功能的影响。同时，本项目也将进行一系列的力学性能测试和形状记忆恢复的实验。这些实验结果将用来验证和优化模型。因此，本项目将通过理论和实验手段理解变形温度，应变率, 形变取向和物理时效对非晶态高聚合物的力学性质和形状记忆功能的影响。这些结果将有助于对非晶态高聚物基础理论的研究和促进形状记忆高分子的应用。

本项目通过实验和理论相结合研究非晶态高聚物的大变形热力学行为和形状记忆效应。在形状记忆方面，研究了热塑性高聚物的形状记忆效应、热固性高聚物的可调控形状记忆效应、以及通过结合溶剂调控热固性高聚物的形状记忆区间。在非晶态高聚物的热力学行为方面，研究了物理老化和预变形对非晶态高聚物应力响应和热容响应的影响，通过实验研究不同老化温度和老化时间对高聚物屈服应力的影响，并研究了温度、应变率、交联度和预变形对高聚物应变强化行为的影响。这些成果促进了非晶态高聚物的基础理论发展和形状记忆高聚物这类智能材料的应用。依托本项目项目负责人发表第一/通讯作者SCI论文15篇，包括International Journal of Solids and Structures, Mechanics of Materials, International Journal of Non-Linear Mechanics, Journal of Applied Mechanics等力学主流期刊，并培养多名研究生。