[en] Shape memory polymers (SMP) and their composites (SMC) are materials exhibiting morphing capabilities that can be applied to numerous applications, including aerospace or biomedical engineering. The changes of shape of the material are triggered by modifying its temperature. Amongst the possible activation methods, Joule resistive heating occurring when an electric current is injected directly in the material is particularly attractive since it is fast and does not require an external heating source. This method, however, requires the electrical resistivity of the polymer to be decreased by the use of conductive fillers. In addition, a suitable activation requires the temperature increase of the sample to be predicted accurately. In this work we establish and investigate the different analytical expressions that can be used to predict the characteristics of the resistive heating of an electroactive shape memory composite with rectangular cross-section [1]. We determine the parameters that are important to understand the temperature increase that happens either when a constant current is injected in the sample or when this current is injected at constant power. The results are compared to measurements of the temperature distribution at the surface of a conductive shape memory composite consisting of covalent poly(ε-caprolactone) matrix filled with 3 wt% of multiwall carbon nanotubes [1]. The experimental temperature distribution across the sample can be reproduced using the analytical expressions, which can then be used to predict the temperature increase for samples of various sizes and properties.
References:
[1] Clara Pereira Sánchez et al. Resistive heating of a shape memory composite: analytical, numerical and experimental study (2022) Smart Mater. Struct. 31 025003.
