摘要
Multi-wall carbon nanotube filled shape memory polymer composite(MWCNT/SMC)possessed enhanced modulus,strength,and electric conductivity,as well as excellent electrothermal shape memory properties,showing wide design scenarios and engineering application prospects.The thermoelectrically triggered shape memory process contains complex multi-physical mechanisms,especially when coupled with finite deformation rooted on micro-mechanisms.A multi-physical finite deformation model is necessary to get a deep understanding on the coupled electro-thermomechanical properties of electrothermal shape memory composites(ESMCs),beneficial to its design and wide application.Taking into consideration of micro-physical mechanisms of the MWCNTs interacting with double-chain networks,a finite deformation theoretical model is developed in this work based on two superimposed network chains of physically crosslinked network formed among MWCNTs and the chemically crosslinked network.An intact crosslinked chemical network is considered featuring with entropic-hyperelastic properties,superimposed with a physically crosslinked network where percolation theory is based on electric conductivity and electric-heating mechanisms.The model is calibrated by experiments and used for shape recoveries triggered by heating and electric fields.It captures the coupled electro-thermomechanical behavior of ESMCs and provides design guidelines for MWCNTs filled shape memory polymers.
多壁碳纳米管填充形状记忆聚合物复合材料(MWCNT/SMC)具有增强的模量、强度和导电性,以及优异的电热形状记忆性能,具有广阔的设计场景和工程应用前景.热电触发的形状记忆过程包含复杂的多物理机制,特别是当热电触发的形状记忆过程与基于微观机制的有限变形耦合时.建立多物理场有限变形模型是深入了解ESMC电-热耦合性能的必要条件,有利于ESMC的设计和广泛应用.考虑到MWCNTs与双链网络相互作用的微观物理机制,本文建立了基于MWCNTs之间形成的物理交联网络和化学交联网络的两个叠加网络链的有限变形理论模型.一个完整的交联化学网络被认为具有熵-超弹性特性,与一个物理交联网络叠加在一起,其中渗透理论基于电导率和电热机制.该模型通过一系列实验进行了标定,并进一步用于电场下直接加热和电加热的多重(电和热)触发形状恢复.通过数值算例研究了电激活形状记忆复合材料(ESMCs)的形状记忆行为,以及MWCNT浓度、电场强度和加载应变率对其形状记忆行为的影响.该模型在捕获ESMC的电-热耦合行为方面具有良好的可行性,为MWCNTs填充形状记忆聚合物提供了理论理解和设计指导.
基金
supported by the National Natural Science Foundation of China(Grant No.12172125)
the Science Foundation of Hunan Province(Grant No.2022JJ30119).
