Biomedical Engineering Reference
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to be 39.8 mJ/m
2
[14]. As shown in
Figure 4.3
, the polar acid-base
part of the surface energy coverage dependency is characteristic
with minor linear increase with increasing coverage ranging from
0.7 mJ/m
2
for 0% coverage up to 6.8 mJ/m
2
for 100% coverage.
The results obtained indicate dominance of the dispersive part of
the surface energy. The surface energy distribution is characteristic
with narrow distribution of the total surface energy ranging from
10-34 mJ/m
2
with the maximum at 18.5 mJ/m
2
(
Figure 4.4
). The
total surface energy distribution is controlled by distribution of
the dispersive part which ranges from 3.3-34.1 mJ/m
2
. It is evident
that the polar surface active sites are of relatively low energy, again
documenting the low polarity of sample surface. On the other hand,
the dispersive part surface energy distribution is of a wider character
reflecting the fact that a higher number of structural elements are
responsible for this behaviour [13].
30
20
10
0
0.00
0.05
0.10
0.15
Coverage (n/nm)
Figure 4.3
Profile plot of total surface energy and its components
for HA powder under study. Empty circle: total surface energy;
empty triangle: dispersive part of surface energy; and empty
square: acid-base part of surface energy
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