Durability of Joule effect of 3D printed carbon black/polylactic acid: electrical cyclic tests and analytical modelling

The reliability of electro-induced heating of shape memory polymers is an issue to be considered in the development of 3D printed actuators. In this paper, the influence of electrical cyclic loading on the thermal behaviour and the microstructure of 3D printed samples made of polylactic acid filled with carbon black particles is analysed. The optimisation of the electrical conductivity through printing parameters and predictive analytical modelling are also conducted. Three different values of voltage are compared (20V, 25V and 30V), showing that the higher the voltage, the higher the temperature within the samples and the faster the heating and cooling rates. It is also demonstrated that, after ten electrical cycles, for high voltages, the crystallinity ratio of the material increases, leading to a better conductivity of the sample. However, the possible consequences of these microstructural modifications on the mechanical behaviour must also be considered in the design of a 4D printed device in order to find the best compromise.