Enhanced thermally conductive TPU/graphene filaments for 3D printing produced by melt compounding

Conducting polymers are a potential solution to the issue of wide‐range manufacture of flexible electronics, since many polymers are suitable to advanced fabrication methods, such as fused deposition modeling (FDM) 3D printing. Therefore, it is proposed in this work a ductile thermoplastic polyurethane (TPU)/graphene nanocomposite with enhanced thermal conductivity that would be suitable for additive manufacturing processes. The nanocomposites were produced by melt compounding technique, which does not require the use of toxic solvents and is characteristic of being used by the thermoplastic industry. The filaments were then analyzed in terms of graphene dispersion, microstructural changes, mechanical behavior, and thermal conductivity. It was verified that graphene does not have a good interaction with the TPU matrix, presenting voids at the interface and forming agglomerates at higher contents. However, it was able to affect the TPU's hard segments organization, leading to a more ordered structure up to 1.0 wt%. Consequently, the thermal conductivity was enhanced up to the graphene concentration by about 14% in relation to neat TPU. Additionally, even though the system presented a poor interface, no mechanical properties were lost, that is, the composite remained ductile even after graphene insertion, which is extremely interesting for additive manufacturing processes. Filaments for 3D printing with high thermal conductivity were obtained by melt mixing of TPU and graphene. The result enables this nanocomposite as a multifunctional material, that is, presenting several unique properties in the same product.