Application of interpolated double network model for carbon nanotube composites in electrothermal shape memory behaviors

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. (Figure presented.).