Page 94 - IJB-9-3

International Journal of Bioprinting Biocompatible 3D printing photosensitive resin

Figure 4. Thermal properties of NIPUA. (A) Heat deflection temperature, (B) thermal stability, and (C) differential thermal gravity.

large, the molecular weight between the joints is small, at 410°C, which illustrates one-step thermal degradation
[21]
and the fragment heat transfer and stress transfer ability is process . The maximum decomposition rate was slightly
reduced. The number of effective chains and chain support enhanced as PEGDA content increases, which may be
inhomogeneity become larger with the crosslinking density. resulted from the lower bond dissociation energy of C-O
Despite the PEGDA-16 having higher crosslinking density, (330 kJ/mol) than that of C-N (337.7 kJ/mol) .
[24]
PEGDA-12 still has the best mechanical properties.
3.5. Hardness and impact resistance of NIPUA
3.4. Thermal properties of NIPUA The hardness and notched impact strength properties of
The heat deflection temperature is the limit for the NIPUA was shown in Table 2. The hardness of the resin
application of photosensitive resins. As shown in was decreased from 84 D to 81 D after PEGDA addition.
Figure 4A, PEGDA content influenced the heat deflection There is a slight difference between hardness with different
temperature of the photosensitive resin, with a variation PEGDA contents. PEGDA is a flexible molecule and
range from 66.9°C to 79.5°C. The maximum temperature could increase the toughness of the resin and decrease
was reached when the PEGDA content was 12 wt.%. its hardness. The notched impact strength of NIPUA was
These data indicated that the resin did not deform at room slightly reduced after PEGDA addition, which was resulted
temperature. from incomplete curing of the resin and reduced impact
strength by high PEGDA content.
TGA characterized the internal structure and
thermal properties of NIPUA (Figure 4B). The 5% mass 3.6. Corrosion resistance of NIPUA
decomposition temperature was significantly enhanced The acid and alkaline resistance morphology of NIPUA
with the increase of PEGDA content. The highest is shown in Figure S2A. The surface morphology of the
temperature was 253.92°C. This may have resulted from resin was changed in 5 wt.% H SO solution. The surface
4
2
more hydrogen bonds formed between the different N of PEGDA-4, PEGDA-8, and PEGDA-12 did not show
atoms . Furthermore, according to differential thermal significant morphology changes, indicating that the
[23]
gravity (DTG) curves (Figure 4C, Table S3 in Supplementary PEGDA addition enhanced the resistance against acid
File), there was only one maximum decomposition rate corrosion (Figure S2A). Alkaline erosion leads to black

Volume 9 Issue 3 (2023) 86 https://doi.org/10.18063/ijb.684