Biomedical Engineering Reference
In-Depth Information
80
70
60
50
40
30
20
10
0
8
7
6
5
4
3
2
1
0
CPC
Biphasic
Mixed
Alginate
CPC
Biphasic
Mixed
Alginate
Dry
We t
Dry
Wet
(a)
(b)
10
Biphasic
CPC
CPC
Biphasic
Mixed
Alginate
8
6
4
Mixed
Alginate
2
0
0510
15
20
25
30
35
40
Strain (%)
(d)
(c)
FIGURE 4.12
(a) Compressive strength and (b) modulus of plotted CPC-alginate scaffolds in dry and wet
state, and (c) compression curves and (d) photographs of dry scaffolds after compression of up
to 30% deformation. All scaffolds were prepared with the same geometry (strand distance and
number of strands). Compressive strength and modulus of pure alginate and alginate-CPC
mixed scaffolds were calculated on the values at 15% strain, while for the CPC and CPC-algi-
nate biphasic scaffolds by using the maximal values.
Whereas pure CPC scaffolds, fabricated without sintering, are character-
ized by their inherent brittleness and poor mechanical strength, most pure
polymer scaffolds possess an insufficient stiffness. Pure alginate and mixed
CPC-alginate scaffolds are polymeric bulk materials, which show the typical
behavior of stress increase with growing compressive deformation but with-
out collapse of the structures. The pure CPC scaffolds, on the other hand,
react as expected for ceramic bulk materials with a sharp increase of stress at
the beginning of the compression followed by a drop to nearly zero quickly
after reaching the maximum value, that is caused by crack formation, result-
ing in a complete collapse of the architecture. Biphasic CPC-alginate scaf-
folds consist of both polymeric and ceramic bulk material. In case of these
composite scaffolds, stress increased with the compressive strain linearly
at the beginning until the maximum, which was significantly higher than
those of pure CPC scaffolds. In contrast to the latter, the stress did not fall to
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