This work focus on the development of polymeric blends to produce multifunctional materials for 3D printing with enhanced electrical and mechanical properties. In this context, flexible and highly conductive materials comprising poly(vinylidene fluoride)/thermoplastic polyurethane (PVDF/TPU) filled with carbon black‐polypyrrole (CB‐PPy) were prepared by compression molding, filament extrusion and fused filament fabrication. In order to achieve an optimal compromise between electrical conductivity, mechanical properties and printability, blends composition was optimized and different CB‐PPy content were added. Overall, the electrical conductivities of PVDF/TPU 50/50 vol% co‐continuous blend were higher than those found for PVDF/TPU 50/50 wt% (i.e., 38/62 vol%) composites at same filler content. PVDF/TPU/CB‐PPy 3D printed samples with 6.77 vol% filler fraction presented electrical conductivity of 4.14 S m−1 and elastic modulus, elongation at break and maximum tensile stress of 0.43 GPa, 10.3% and 10.0 MPa, respectively. These results highlight that PVDF/TPU/CB‐PPy composites are promising materials for technological applications.

Electrically conductive composites of thermoplastic polyurethane (TPU), poly(vinylidene fluoride) (PVDF), and carbon black-polypyrrole (CB-PPy) were prepared by melt compounding followed by compression molding or by filament production followed by fused filament fabrication (FFF). The storage modulus (G 0 ) and complex viscosity (η*) of the composites increased with the addition of CB-PPy leading to a more rigid material. The electrical and rheological percolation threshold of composites were 5 and 3 wt%, respectively. In fact, composites with 5 wt% or more CB-PPy content display G 0 higher than G 00 indicating a solid-like behavior. Furthermore, the addition of CB-PPy increased the electrical conductivity of all composites. However, the electrical conductivity values of composites containing 5 and 6 wt% of CB-PPy produced by compression molding are one and seven order of magnitude higher than those of FFF composites with same composition. Compression molded and 3D printed composites with 6 wt% of CB-PPy displayed high sensitivity/gauge factor, large measurement range and reproducible piezoresistive response during 100 loading-unloading cycles for both processing methods. The results presented in this study demonstrated the potential use of FFF for producing piezoresistive flexible sensors based on PVDF/TPU/CB-PPy composites.

Hybrid conducting composites comprising thermoplastic polyurethane (TPU) and mixtures of carbon black modified with polypyrrole (CB-PPy) and carbon nanotubes (CNT) were prepared by melt mixing process. The electrical conductivity, rheological properties and electromagnetic shielding effectiveness (EMI SE) of TPU/CB-PPy and TPU/CNT composites were also investigated those results observed for TPU/CB-PPy/CNT hybrid composites. TPU/CNT composites show a very sharp insulator-conductor transition and the electrical percolation threshold was about 1 wt% of CNT, which was lower than that found for TPU/CB-PPy (7 wt%). Moreover, EMI SE values of TPU/CNT composites were higher than those for TPU/CB-PPy due to the denser CNT conductive pathway into TPU matrix. In order to achieve the highest electrical conductivity and EMI SE values, mixtures of CB-PPy/CNT were added in the composites in different mass fractions. In fact, the electrical conductivity values increased by combining CB-PPy and CNT, resulting in hybrid composites of TPU/CB-PPy/CNT with higher EMI SE values when compared to TPU/CB-PPy composites. The present study demonstrates the potential use of hybrid polymer composites containing 5 or 8 wt% of CB-PPy/CNT at specific CB-PPy/CNT ratios with good processabilty and EMI SE values as high as −20 dB indicating the potential use of these materials for electromagnetic shielding application in the X-band frequency region.