Page 24 - eBook_Proceedings of the International Conference on Digital Manufacturing V1

Proceedings of the International Conference on Digital Manufacturing –
Volume 1

At Day 7, the Dogbone samples exhibited the highest mass loss
percentage (0.2366%), followed by Cube (0.1821%) and Bar
(0.1473%). This trend suggests that the initial degradation rate
was slightly faster in geometries with higher surface area-to-
volume ratios, which is consistent with findings by Sun et al. (Sun
et al., 2024), who demonstrated that samples with a greater
number of surface grooves, resulting in increased surface area-to-
volume ratios, underwent more rapid degradation rates compared
to smoother counterparts. By Day 14, the difference in weight loss
among the samples began to narrow, with all three geometries
showing similar values around 0.23–0.25%. From Day 14 to Day
21, a notable increase was observed in the Cube samples, reaching
0.3617%, while the Bar and Dogbone samples showed more
moderate increases (0.2434% and 0.3113%, respectively). By the
end of the test period (Day 28), the Dogbone samples recorded the
highest cumulative mass loss at 0.3903%, followed closely by
Cube (0.3610%) and Bar (0.2944%).

The weight difference percentage for all samples over the 28-
day immersion period was minimal, with values ranging between
approximately 0.15% and 0.39%. This indicates that PLA
undergoes a slow hydrolytic degradation process in SBF, which is
consistent with its known characteristic, a slowly degradable
polymer (Taib et al., 2023). This slow degradation rate suggests
that PLA can maintain structural integrity over a clinically
relevant timeframe for temporary implant applications.

In addition, the degradation trends did not follow a strictly
linear pattern across time. For instance, the Cube sample exhibited
a sharp increase in weight difference between Day 14 and Day 21,
while the Dogbone sample showed another significant rise
between Day 21 and Day 28. These non-linear changes may
reflect the influence of various environmental and material-related
parameters that govern PLA hydrolysis, including temperature,
local pH, water absorption capacity and the diffusion of
degradation fragments within the polymer matrix (Elsawy, Kim,
Park & Deep, 2017; Brito, Andrianov & Sukhishvili, 2022). Such
variations may cause time-dependent shifts in hydrolysis

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