Study of the interlayer adhesion and warping during material extrusion-based additive manufacturing of a carbon nanotube/biobased thermoplastic polyurethane nanocomposite
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Date
2021-04-07Author
Candal, María Virginia
Fernández San Martín, Mercedes
Hernández Aguirresarobe, Roberto
Santamaría Ibarburu, Pedro Antonio
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Polymer 224 : (2021) Article ID 123734
Abstract
A thermoplastic bio-polyurethane from renewable sources (TPU) and the nanocomposite developed by mixing it
with carbon nanotubes (CNT) are investigated as potentially adequate for Material Extrusion-based Additive
Manufacturing (EAM). Thermal and rheological features are studied from the perspective of their liaisons with
printing adequacy and conditions. As predicted by rheology, both samples show good performance in filament
elaboration and flow in the nozzle. Warpage is observed for TPU, but not for the nanocomposite, which is due to
the effect of CNT nanoparticles on polymer chains dynamics. At the studied printing velocities, interlayer
adhesion strength is independent of printing velocity implying that there is no significant chain orientation
which can induce changes in the TPU entanglements. The nanocomposite shows a lower welding strength,
notwithstanding both have the same chain entanglements density. This is explained by considering that the
higher viscosity of TPU/CNT, as compared to TPU, reduces the melt diffusion coefficient.