EFFECT OF SHEAR ON THE ELECTRICAL PROPERTIES OF POLYBUTILENE SUCCINATE-CO-ADIPATE/MWCNT NANOCOMPOSITES
Alodi Pascal, Mercedes Fernandez, Robert Aguirresarobe, Itxaso Calafel
POLYMAT and Advanced Polymers and Materials: Physics, Chemistry and Technology, Faculty of Chemistry, University of the Basque Country UPV/EHU, Donostia-San Sebastian, Spain.
Carbon nanocomposites are materials of great interest. These materials have generally been processed using conventional techniques such as injection and compression moulding. Various studies have shown that, depending on the processing technique used, electrical properties are affected since there is hardly any shear in techniques such as compression moulding, but high shear in injection moulding. However, recently, they are starting to be processed using more advanced techniques, such as additive manufacturing that has shown great potential for processing highly complex customised structures with electrical conductivity. In this work, the influence of shear on the electrical properties of poly(butylene succinate-co-adipate) (PBSA) nanocomposites with multi-walled carbon nanotubes (MWCNT) was studied. For this purpose, mixtures with various MWCNT concentrations were prepared and processed by injection, compresion and 3D printing, evaluating the resulting conductivity. The results show that the higher the shear applied in the processing, the higher the MWCNT concentration is needed to achieve the percolation threshold. To understand the effect of shear and to replicate what happens in processing, rheological measurements have been performed on the molten material at small amplitude oscillatory shear (SAOS) and large amplitude oscillatory shear (LAOS) using a dielectric spectroscopy coupling set up to simultaneously measure the electrical and rheological behaviour. Thus, it has been determined that the rheological threshold differs from the electrical percolation threshold.