Page 284 - IJB-9-4

International Journal of Bioprinting 3D printing of continuous fiber reinforced PLA/PGA composites

Figure 4. Experimental setup for tensile tests.

with a random pattern of black paint spots. The purpose 2.4. Statistical analysis
of painting is to form scatter spots for the strain field Group data are presented as mean ± standard deviation.
calculation, and the thickness of paint layer is very thin Statistical significance was determined by one-way analysis
and has no negative impact on the tensile strength. of variance (ANOVA). The significance level was set at p <
0.01 (**) and p < 0.0001 (****).
2.3.3. Internal defect testing
A micro-X-ray 3D imaging system (YXLON Cheetah, 3. Results
Germany) was applied to analyze the internal defects of
the specimens, and the internal pore geometries, volumes, 3.1. Results of thermal analysis
and spatial distributions were also analyzed. A scan The printing temperature (the temperature of the nozzle)
resolution of 5 μm, a peak tube potential of 80 kV, and a is an important process parameter of FDM. On the one
target current of 35 μA were set as the basic measurement hand, it is necessary to make the molten PLA have a high
parameters. temperature to ensure its good fluidity, and on the other
hand, it is also necessary to ensure that the PGA fiber
2.3.4. Analysis of printed specimen morphology wrapped with PLA will not be thermally decomposed.
A high-speed camera (Phantom V9.1, Vision Research, Thermogravimetric analysis (TGA) and DSC tests
Inc., USA) was used to observe the extruded material were conducted to obtain the decomposition limit
morphology of a single deposition line at different printing temperatures and melting points of the two materials,
heights, mainly to observe the positions of the fibers in respectively, which were used to guide the selection range
the matrix material. The capture frequency of the high- of the printing temperature. The TGA and DSC results of
speed camera was 800 Hz. A digital microscope (VHX- the PGA fiber and PLA materials are shown in Figure 5.
6000, KEYENCE, Japan) was used to observe the cross- The TGA curves in Figure 5A show that most of the mass
sectional morphology of single deposited lines and tensile (over 90%) was lost between 250°C and 390°C, and the
specimens. Field emission electron scanning microscopy initial decomposition temperatures of the PLA and PGA
(FESEM, JSM-7610PLUS, Japan) was used to observe materials were 347.7°C and 306.5°C, respectively. The
the cross-sections of the PLA/PGA composites and the largest decomposition rates of the PLA and PGA materials
fracture morphologies of the tensile specimens. were 28.5%/min and 21.2%/min at 367.6°C and 339.1°C,

Volume 9 Issue 4 (2023) 276 https://doi.org/10.18063/ijb.734