Page 295 - IJB-10-1

International Journal of Bioprinting Scaffolds manufacturing by fused deposition modeling

Figure 9. Compression properties of the scaffolds at different immersion times in terms of (a) stress at yield point and (b) deformation at yield point.

showed a compressive stress at yield point of 12.2 MPa with a composites considered because during the immersion in
deformation at break of 16.3%. After 8 weeks of immersion, PBS, a hydroxyapatite layer was formed, as observed in the
compressive stress at yield point of 9.3 MPa and deformation morphology of the surface analysis. 94
at break of 8.3% were measured, respectively.

As in tensile tests on 3D-printed specimens, the 4. Conclusion
best strength and deformation values were obtained This work showed that P(3HB-co-3HHx)/HA composites
for the polymeric material without hydroxyapatite. can be effectively used for the fabrication of scaffolds by
The incorporation of an increasing amount of the FDM. The manufacturing method involved different thermal
osteoconductive additive promoted a reduction of treatments, including a compounding process to obtain the
mechanical properties such as the stress and deformation composites, an extrusion process to obtain the filaments
at yield point, as shown in Figure 10. Similar effects employed in the FDM process, and a 3D printing process to
under compression tests have been reported for additive obtain the samples. All these cycles resulted in slight thermal
manufactured scaffolds made of PLA and nHA. 91 degradation, as seen from DSC studies with a higher degree
3.6. Chemical analysis of the PBS of the P(3HB-co- of crystallinity and a lower cold crystallization temperature.
3HHx)/HA nanocomposites DSC test also indicated that the incorporation of ceramic
Figure 11 shows the chemical analysis of the surface of the nanoparticles decreased the crystallinity of the material.
scaffolds before and after immersion in PBS. The scaffolds TGA showed that cleavage of polymer chains reduced the
before immersion showed characteristic peaks of P(3HB- T up to 3°C for the same composite. The degradation
max
co-3HHx) at 1719 cm belonging to the C=O stretching effect was also observed in the rheology analysis, as each of
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vibration of the crystalline region of the polymeric structure. the thermal cycles promoted a slight reduction of viscosity
Additionally, peaks also appeared at 2928 cm and 2850 as a result of the incorporation of nHA.
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cm corresponding to C-H vibration and asymmetric Overall, increasing the amount of nHA in the
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stretching of CH , respectively. 32,92 For the composites with composites decreased their tensile strength and their
2
hydroxyapatite, a peak appeared in the range between 1020 ductility. On the other hand, their stiffness increased with a
cm and 1080 cm , which corresponds to the phosphate tensile modulus near 750 MPa for the neat polymer, while
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groups present in HA. The presence of this peak was more values near 950 MPa for the 10 wt% nHA were obtained.
93
noticeable when the amount of hydroxyapatite in each Regarding the pattern employed, the raster angle of 0°gave
composite was increased. After immersion, the spectrum rise to the highest strength, while the best ductility was
of the scaffolds changed significantly because a coating obtained with the 45°/–45° pattern with a 17.5% value in
layer was formed on the polymer surface, resulting in the the elongation at break. The compression behavior of the
disappearance or the low intensity of peaks that could be scaffolds was diminished in the case of high amounts of
observed at 2928 cm and 2850 cm and the reduction of nHA, presenting 13.5 MPa for the neat polymer at week
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intensity at 1719 cm (Figure 11b). The peak associated 0 and 12.2 MPa for the 10 wt% nHA. Moreover, samples
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to hydroxyapatite (1020–1080 cm ) appeared in all the were subjected to an immersion process in PBS solution
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Volume 10 Issue 1 (2024) 287 https://doi.org/10.36922/ijb.0156