Study of the interlayer adhesion and warping during material extrusion-based additive manufacturing of a carbon nanotube/biobased thermoplastic polyurethane nanocomposite

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.

Tailoring interfacial properties of 3D-printed continuous natural fiber reinforced polypropylene composites through parameter optimization using machine learning methods

“…According to the experimental design, CRFRPP with different printing parameter combinations were manufactured and their interfacial properties (interlayer and intralayer adhesion properties) were examined. Inspired by these works [32,[37][38][39][40][41][42][43] and ASTM D1938 investigated the tensile properties of ME-AM fabricated continuous flax fiber reinforced PLA composites. The results showed that the longitudinal tensile modulus and strength of continuous flax fiber reinforced PLA composites were improved by a factor of 4.5.…”

Rheology, crystallization, and process conditions: The effect on interlayer properties in three-dimensional printing

“…The degree of chain orientation at the interlayer region as well as the morphological features of printed parts are strongly influenced by the processing parameters 28 . The adhesion energy (or tear energy) determined from the trouser tear tests for PLA prints serves as a measure of the interlayer weld strength 44,48,55,56 . Figure 5…”

3D‐Printed Functional Polymers and Nanocomposites: Defects Characterization and Product Quality Improvement

“…For FFF, agglomeration of CNTs can lead to flux instability, blockage of the nozzles, and failure of the printing work. [128,147] Candal et al [148] studied the correlation between the rheological features and thermal behavior (using calorimetric and dilatometric experiments) of a bio-based TPU/4 wt% CNT nanocomposite and its performance during FFF. The results obtained showed that the viscous modulus (G 00 ) is greater than the elastic modulus (G 0 ) of the nanocomposites, except at frequencies close to 100 Hz, at which the rubbery zone starts and G 0 is greater than G 00 for both the neat and filled TPU.…”