碳纳米管“桥联”的TiNi合金丝/形状记忆环氧树脂复合材料界面与力学行为的关联性研究

Composites made from shape memory alloy (SMA) wires and shape memory polymers show potential for application in active structural control areas, and they have received increasing attention in the last decade. The performance of composite applications is heavily dependent on the quality of the SMA-matrix interface. Strong interface is required to transfer the stresses and strains from the SMA constituents to the surrounding matrix, making the investigation of the interface adhesion an important endeavor...In order to improve the interfacial bonding strength and interface layer strength simultaneously, a new interface structure is designed and prepared. The amino carbon nanotubes (CNTs) are planted on the TiNi wire surfaces by electroplating and chemical etching technology leading to the formation of bridged interface between TiNi wires and shape memory epoxy. In order to clarify the effect of CNT on interface,the variations of interface structure and interfacial adhesion as factor of CNT are investigated. Then the correlation between interface structure and mechanical behavior is studied, and the role of interface structure in the stress and strain transfer process will be demonstrated...The aim of the project is to establish the interface structure design and preparation guidelines for optimizing the properties of TiNi wire/shape memory polymer composites.

TiNi合金丝/形状记忆聚合物复合材料集两者的优势为一身，成为当今主动变形结构材料的新秀。该复合材料的性能很大程度上依赖于界面结合强度，只有当界面结合强度足够高时，TiNi合金丝动作产生的应力和应变，才能被有效地传递到聚合物基体中。因此，探索提高界面结合强度的原理和方法是该领域研究的关键科学问题。本项目提出利用碳纳米管"桥联"TiNi合金丝与形状记忆环氧树脂的界面，同时提高界面粘结强度和界面层强度的新思路。设计TiNi合金丝/形状记忆环氧树脂复合材料界面结构，系统研究碳纳米管引入对界面结构和结合状态的影响规律和机制，揭示碳纳米管对界面的增效机制；建立界面结构与宏观性能之间的内在联系，为TiNi合金丝/形状记忆聚合物复合材料的发展和性能优化提供理论指导。

本项目设计了一种碳纳米管“桥联”的TiNi合金丝/形状记忆环氧树脂复合材料界面结构：利用电镀和选择性化学刻蚀的方法将氨基化碳纳米管根部“植布”于TiNi合金丝表面，而碳纳米管裸露端表面的氨基促进环氧树脂固化，实现TiNi合金丝与形状记忆环氧树脂之间的化学连接，从而在提高环氧树脂与TiNi合金丝界面粘结强度的同时提高界面层强度。研究表明，当碳管浓度为0.6g/L，沉积电压为2V，沉积时间为2min时，得到的结构最适于作为TiNi合金丝与形状记忆环氧树脂的中间过渡层，界面剪切强度可达60MPa以上，优于酸洗、KH560处理和电化学沉积ZnO处理的界面。界面失效分析表，碳纳米管的存在和镀层的粗糙度提高了界面处的接触面积，从而提高了界面的粘结强度，同时，碳纳米管对界面层处环氧树脂的增强效果也使界面不易发生拉脱现象，使剪切强度大于基体的强度，避免了界面失效。对复合材料力学行为的研究表明，TiNi合金丝的加入可以同时提高聚合物基体室温和高温条的弹性模量和拉伸强度，对高温力学性能的提高尤为明显，界面优化起到关键作用。当合金丝含量为1vol%时，预应变为8%时，形状回复力提高近3倍，形状固定率和形状回复率降低较小，均接近100%。利用TiNi合金丝/形状记忆环氧树脂复合材料制备的太阳能板展开桁架驱动机构可实现水浴回复20次无损伤。