Biomedical Engineering Reference
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4.3 Results and Discussion
The surface properties of HA powders were analysed by several
experimental techniques. The specific surface area of HA powders was
found to be 15 m
2
/g as observed by the BET technique, for a sample
density of 1.00 g/cm
3
. To characterise the exact moisture content
in the studied samples, DTA-TGA measurements were performed.
These showed gradual sample mass loss with increasing temperature,
having three distinct degradation regions (
Figure 4.1
). The first one,
characteristic for water loss of 13.72 wt% up to 180 °C and the
second and third regions, characteristic of a two-stage polysaccharide
degradation starting at 180 and at 300 °C. The observed weight loss
for the second region was 38.55 wt% and 12.26 wt% for the third
region. Typical shapes of the particles of the HA powder studied
are shown in
Figure 4.2
. These were characteristic spherical and
cylindrical shapes of approximately 70 mm in diameter.
100
80
60
40
100
200
300
400
500
Temperature (°C)
Figure 4.1
TGA DTA degradation pattern of HA powder under
study
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