SAMPE Journal - July/August 2024 - 19

Figure 3. Water diffusion test results: (a) water absorption (%) and (b) maximum water absorption level
(%) of 3D-printed ABS specimens.
Figure 4. Water diffusion test results: (a) water absorption (%) and (b) maximum water absorption
level (%) of 3D-printed SCF/ABS specimens.
resolution set at 13.77 μm for the voxel edge size,
7000 projections, and a complete 360º imaging
rotation lasting 4 hours. The extensive dataset
consisting of 7000 projections and a complete
360º rotation offered a three-dimensional (3D)
perspective of the microstructural characteristics
of the specimen.
2.4 Experimental Results
2.4.1 Absorption Properties
Figure 3 shows the evolution of water absorption,
measured by a weight
increase, of neat ABS
specimens under both uni- and bi-directional
water diffusion. At an early stage of water diffusion,
SBZ and SUZ specimens exhibited similar water
absorption trends. Over time, SBZ specimens
showed a rapid increase in water absorption
and stabilized at ~8.50% after ~170 hours. It is
important to note that water absorption in Figure 3
is plotted with respect to the square root of time,
thus ~13hr in the x-axis of the figure corresponds
to the square root of ~170 hours. SUZ specimens
reached their highest level of water absorption
relatively earlier at approximately 90 hours and
then showed a steady increase in water absorption,
reaching the maximum saturation levels (9.5%)
similar to those observed in SBZ specimens. SBXY
specimens demonstrated a weight increase of up to
approximately 6%, whereas SBZ specimens showed
a higher maximum water saturation of ~10%. The
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water absorption for SUZ specimens exhibited
a higher standard deviation compared to SBZ
specimens. This can be attributed to the presence
of random and extensive void distributions within
the specimens, which introduce variability in
their water absorption behavior. As the diffusion
occurs from one face in SUZ, this randomness has
a higher impact on creating variability than the
SBZ specimen where the diffusion occurs from
both faces, providing a more uniform diffusion. In
addition, horizontally printed specimens that have
uni-directional (SUXY) and bi-directional (SBXY)
water diffusion consistently showed that SUXY
specimens absorbed a slightly greater amount of
water than SBXY. These different water absorption
characteristics became increasingly evident after
approximately 455 hours. Note that the scale of the
x-axis is given in the square root of time, thus 455
hours correspond to ~21 hours in Figure 3a.
The SCF/ABS specimens demonstrated slightly
reduced water absorption levels, underscoring the
impeding influence of SCFs on water diffusion
(Figure 4). Carbon fibers are hydrophobic in
nature, thus the presence of SCFs into ABS matrix
plays a pivotal role to resist the water diffusion into
the SCF/ABS specimen. This resistance to water
diffusion is greater in the transverse direction to
the fiber than along the fiber direction, as there is
a more organized pathway for the water to diffuse
in the fiber direction. SUZ specimens absorbed
JULY AUGUST 2024
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SAMPE JOURNAL |
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SAMPE Journal - July/August 2024

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