Study of the functional properties of the piezoresistive effect and Joule heating of electrically conductive composites based on 3D-printed polymers with a PEDOT:PSS surface layer

The paper presents the results of a comprehensive study of the functional properties of electrically conductive composites obtained by surface modification of polymer materials for 3D printing – polylactide (PLA), polyethylene terephthalate glycol (PETG), and thermoplastic polyurethane (TPU) – with a conducting polymer complex of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS). The piezoresistive response of the samples was studied under mechanical bending deformation in the range of 0–2%. The gauge factor (GF) was calculated. The PETG + PEDOT:PSS composite demonstrated the highest sensitivity with a maximum GF of ≈ 47, which is due to the formation of a rigid and well-adhered conductive layer that is prone to cracking during deformation. For the PLA + PEDOT:PSS and TPU + PEDOT:PSS composites, the maximum GF values were ≈ 19.5 and ≈ 13.5, respectively. A study of the Joule heating effect under a constant voltage of 70 V revealed a slight increase in the sample temperature (ΔT = 0.5–1.9 °C), which is due to the high resistivity of the surface layer. It was shown that, despite their limited effectiveness for active heating purposes, the materials exhibit stability when subjected to current flow. These findings demonstrate the potential of these composites for the development of passive strain sensors and flexible electronic components using additive manufacturing techniques in nuclear power plants (NPPs).