Author Contributions
Conceptualization, J.B. and E.X.; methodology, J.B., E.X., P.B. and M.C.; validation, J.B., M.C. and J.M.P.; formal analysis, J.B. and E.X.; investigation, J.B., E.X., P.B., M.C., J.M.P. and J.A.P.; writing—original draft preparation, J.B., P.B. and E.X.; writing—review and editing, J.B. and E.X.; funding acquisition, J.B. and E.X. All authors have read and agreed to the published version of the manuscript.
Figure 1.
(a) Schematics of top-down MIP-SL printer. X and Y axis are located on the projection plane, whereas Z axis correspond to the manufacturing direction. (b) Detail of the construction platform of the MIP-SL equipment.
Figure 1.
(a) Schematics of top-down MIP-SL printer. X and Y axis are located on the projection plane, whereas Z axis correspond to the manufacturing direction. (b) Detail of the construction platform of the MIP-SL equipment.
Figure 2.
Orientation of compression samples in the printing manufacturing domain: (a) X, (b) Z and (c) Y.
Figure 2.
Orientation of compression samples in the printing manufacturing domain: (a) X, (b) Z and (c) Y.
Figure 3.
Experimental test set-up for reinforced compression specimens (12.7 × 12.7 × 50.4 mm).
Figure 3.
Experimental test set-up for reinforced compression specimens (12.7 × 12.7 × 50.4 mm).
Figure 4.
Viscosity curves for resin samples with 40 vol% alumina and different dispersant contents. It can be seen how the shear thickening and shear thinning behaviour shifts towards higher shear rates as it approaches to the optimum dispersant.
Figure 4.
Viscosity curves for resin samples with 40 vol% alumina and different dispersant contents. It can be seen how the shear thickening and shear thinning behaviour shifts towards higher shear rates as it approaches to the optimum dispersant.
Figure 5.
Evolution of relative viscosity at 1.1 s−1 of shear rate with the dispersant content at 40 vol% alumina resins. Each point corresponds to an average of at least three measured viscosity curves. It has a minimum viscosity of 0.5% dispersant indicating a better dispersion of the particles and the optimum dispersant chosen.
Figure 5.
Evolution of relative viscosity at 1.1 s−1 of shear rate with the dispersant content at 40 vol% alumina resins. Each point corresponds to an average of at least three measured viscosity curves. It has a minimum viscosity of 0.5% dispersant indicating a better dispersion of the particles and the optimum dispersant chosen.
Figure 6.
Comparison between selected viscosity curves of reinforced suspensions and base resin. Given the low viscosity of the material, it presents a first irregular shear thinning zone that varies slightly between measurements at low shear rates, but which stabilizes and always presents the same viscosity at high shear rates.
Figure 6.
Comparison between selected viscosity curves of reinforced suspensions and base resin. Given the low viscosity of the material, it presents a first irregular shear thinning zone that varies slightly between measurements at low shear rates, but which stabilizes and always presents the same viscosity at high shear rates.
Figure 7.
(a) Sedimentation rate calculation principle and (b) retained rate for reinforced resins indicating the sedimentation rate of the different developed materials.
Figure 7.
(a) Sedimentation rate calculation principle and (b) retained rate for reinforced resins indicating the sedimentation rate of the different developed materials.
Figure 8.
Evolution of reactivity behaviour front solid load incorporation. From the slopes of each line, (a) the µ and (b) K values are obtained for each formulation according to Equation (1).
Figure 8.
Evolution of reactivity behaviour front solid load incorporation. From the slopes of each line, (a) the µ and (b) K values are obtained for each formulation according to Equation (1).
Figure 9.
Secant modulus mean values for each printing orientation (X in blue, Y in orange and Z in green) according to the solid load content. It can be observed an enhancement of secant modulus after the addition of reinforcement particles.
Figure 9.
Secant modulus mean values for each printing orientation (X in blue, Y in orange and Z in green) according to the solid load content. It can be observed an enhancement of secant modulus after the addition of reinforcement particles.
Figure 10.
Comparison of stress-strain curves for all tested specimens with a solid load content of 0% and 10%. Similar stress-strain curves are found for different orientation samples with the same solid load content.
Figure 10.
Comparison of stress-strain curves for all tested specimens with a solid load content of 0% and 10%. Similar stress-strain curves are found for different orientation samples with the same solid load content.
Figure 11.
Stress-strain curves for a representative compression sample for each solid load content for X orientation.
Figure 11.
Stress-strain curves for a representative compression sample for each solid load content for X orientation.
Figure 12.
Stress-strain curves for a representative compression sample for each solid load content for Y orientation.
Figure 12.
Stress-strain curves for a representative compression sample for each solid load content for Y orientation.
Figure 13.
Stress-strain curves for a representative compression sample for each solid load content for Z orientation.
Figure 13.
Stress-strain curves for a representative compression sample for each solid load content for Z orientation.
Figure 14.
Comparison of stress-strain curves between different solid load content and printing orientation (Blue lines for X samples, oranges lines for Y samples and green lines for Z samples).
Figure 14.
Comparison of stress-strain curves between different solid load content and printing orientation (Blue lines for X samples, oranges lines for Y samples and green lines for Z samples).
Figure 15.
Comparison of conversion ratio distribution along the manufacturing direction for the photocurable material with a 10% SL and a layer thickness of 150 μm according to the energy exposure dose. (a) It can be observed that a large difference is found in the last printed layers (b) Detail of conversion ratio values excluding the last printed layers.
Figure 15.
Comparison of conversion ratio distribution along the manufacturing direction for the photocurable material with a 10% SL and a layer thickness of 150 μm according to the energy exposure dose. (a) It can be observed that a large difference is found in the last printed layers (b) Detail of conversion ratio values excluding the last printed layers.
Figure 16.
Comparison of stress-strain curves for the photocurable material SL10% according to the printing parameters.
Figure 16.
Comparison of stress-strain curves for the photocurable material SL10% according to the printing parameters.
Table 1.
Reinforced resins formulation.
Table 1.
Reinforced resins formulation.
Code | SPOT-HT (wt%) | Alumina (wt%) | Dispersant (wt% 1) | Antifoam (wt%) |
SL 5% | 94.6 | 5.0 | 0.5 | 0.4 |
SL 10% | 89.6 | 10.0 | 0.5 | 0.4 |
SL 15% | 84.6 | 14.9 | 0.5 | 0.4 |
Table 2.
Material FPP parameters and exposure energy dose required to achieve a full conversion ratio during the printing process according to the reinforcement solid load content.
Table 2.
Material FPP parameters and exposure energy dose required to achieve a full conversion ratio during the printing process according to the reinforcement solid load content.
| SL 0% | SL 5% | SL 10% | SL 15% |
---|
μ (mm−1) | 1.139 | 2.45 | 3.69 | 4.59 |
K(cm2/mJ) | 0.0045 | 0.0073 | 0.0094 | 0.0107 |
d0 (mJ/cm2) | 126 | 227 | 252 | 277 |
Table 3.
Secant modulus (MPa) for X samples.
Table 3.
Secant modulus (MPa) for X samples.
EX (MPa) |
---|
SL | S1 | S2 | S3 | S4 | S5 | Mean | St |
0% | 219.48 | 210.42 | 217.91 | 209.29 | 212.61 | 213.94 | 4.53 |
5% | 540.18 | 466.34 | 560.42 | 519.42 | 493.51 | 515.97 | 37.22 |
10% | 705.37 | 674.87 | 553.99 | 586.38 | 661.76 | 636.47 | 63.59 |
15% | 528.59 | 448.65 | 461.06 | 454.79 | 450.21 | 468.66 | 33.85 |
Table 4.
Secant modulus (MPa) for Y samples.
Table 4.
Secant modulus (MPa) for Y samples.
EY (MPa) |
SL | S1 | S2 | S3 | S4 | S5 | Mean | St |
0% | 241.00 | 229.69 | 223.51 | 184.60 | 196.89 | 215.14 | 23.54 |
5% | 458.95 | 495.90 | 547.48 | 428.32 | 447.81 | 475.69 | 47.07 |
10% | 684.78 | 552.60 | 644.77 | 576.72 | 626.97 | 609.41 | 53.00 |
15% | 474.98 | 473.70 | 420.99 | 415.50 | 453.48 | 434.91 | 28.30 |
Table 5.
Secant modulus (MPa) for Z samples.
Table 5.
Secant modulus (MPa) for Z samples.
EZ (MPa) |
SL | S1 | S2 | S3 | S4 | S5 | Mean | St |
0% | 255.02 | 213.95 | 185.61 | 211.49 | 212.41 | 215.70 | 24.92 |
5% | 441.14 | 442.05 | 443.19 | 477.44 | 412.45 | 443.25 | 23.04 |
10% | 650.36 | 604.43 | 714.72 | 607.68 | 621.36 | 639.71 | 45.68 |
15% | 504.41 | 470.35 | 488.02 | 516.63 | 544.94 | 504.87 | 28.37 |
Table 6.
Comparison between Secant modulus (MPa) of SL10% Y samples.
Table 6.
Comparison between Secant modulus (MPa) of SL10% Y samples.
EZ (MPa) |
---|
ΔzLayer (μm) | d (mJ/cm2) | S1 | S2 | S3 | S4 | S5 | Mean | St |
---|
75 | 252 | 684.78 | 552.60 | 644.77 | 576.72 | 626.97 | 609.41 | 53.00 |
150 | 252 | 450.20 | 485.75 | 464.27 | 507.19 | 450.66 | 471.61 | 24.58 |
150 | 580 | 558.73 | 635.36 | 597.11 | 605.00 | 614.69 | 602.18 | 28.19 |