Biomedical Engineering Reference
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s_s_k_h-02 1.0kV 6.5mm x700 SE
50.0um
Figure 4.2
SEM image of studied HA powder
The surface energy profile and its components of the studied HA
powder, based on iGC measurements data, are shown in
Figure 4.3
.
The total surface energy and dispersive surface energy surface coverage
dependencies showed exponentially decreasing curve patterns. The
magnitudes of the determined absolute values of both quantities
(total surface energy as well as of dispersive surface energy) were
34.0 mJ/m
2
for 0% coverage and gradually decreased to 11.7 mJ/m
2
for total surface energy and to 4.9 mJ/m
2
for dispersive surface
energy for 100% surface coverage. The highest energetic sites occupy
approximately only 5% of the HA surface [13]. The significant
difference in measured surface energy absolute values at low and
high coverage indicates a high degree of inhomogeneity between the
highest surface energy sites which have an approximately three-fold
higher absolute value of the surface energy than the lowest energetic
sites. The latter SEA-based absolute value of dispersive surface energy
calculated by the Schultz method [9], correlates very well with the
published data obtained from contact angle measurements of the
apolar dispersive component of the surface tension, which was found
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