Electro-thermo-mechanical modeling of shape memory polymers filled with nano-carbon powder

Abstract

Generally, adding the electroconductive fillers into the polymer matrix is a popular approach to endow the shape memory polymers (SMPs) with electroconductivity. Therefore, the shape memory effects (SMEs) of thermally induced SMPs can also be triggered by the electrical current. In essence, both the thermally activated and electrically activated SMEs share the same driving mechanism without considering the effect of heat conduction. In the paper, the constitutive model for the thermally induced SMPs filled with nano-carbon powder is briefly introduced. Then, a modified model is developed to characterize the effects of filler, deformation, and moisture on the electrical conductivity for the first time. After developing the correlation of electric field with Joule heat, the simulation is executed to display the free recovery of the shape memory polymer composites (SMPCs) with different filler content. It is found that the recovery ratio decreases with the increase of carbon powders for the SMPCs with filler content above the percolation threshold. Besides, a good recovery ratio can also be achieved through the application of a lower voltage.

Experimental characterization of the thermo-electro-mechanical properties of a shape memory composite during electric activation

“…The resistivity of an electroactive SMC has already been reported to vary with filler content [18,19] or temperature [2,8], among others. There are, however, very few reports on the strain dependence of ρ e [5,[19][20][21]. In addition, the monitoring of the electrical properties of the SMC during a full shape memory cycle has, to our knowledge, not yet been covered in spite of its crucial importance for accurately and efficiently controlling the resistive heating of the SMC.…”