Biomedical Engineering Reference
In-Depth Information
6. Air dry the solid-PCL-bioactive glass composite until constant mass is
observed for two consecutive days.
7. Store the dried solid composite in a dry cabinet/desiccator.
d
n
3
r
4
n
g
|
1
A.2 Mathematical Derivation of Melt Extruded Scaffold
Microfilament Diameter from Translational Velocity
Please refer to Figure 9.1 when dealing with this derivation. The theoretical
scaffold filament diameter can be predicted using eqn (A.1):
r
v
i
v
o
d
o
¼
d
i
(A
:
1)
where d
o
is output filament diameter, d
i
is input filament diameter, v
i
is
input velocity and v
o
is output velocity (extruder head speed). Eqn (A.1) is
derived with the assumption that input material volume (V
i
) equals to output
material volume (V
o
) and thermal expansion of polymer is not taken into
account:
V
i
¼
V
o
(A.2)
As the extruded microfilament is cylindrical shaped, the volume of a cylinder
is assumed as shown in eqn (A.3):
volume
¼
p
radius
2
length
(A.3)
So,
2
p
L
i
d
i
2
.
V
i
¼
(A
:
4)
2
p
L
o
d
o
2
V
o
¼
(A
:
5)
where L
i
is input filament length and L
o
is output filament length.
By substituting eqn (A.4) and (A.5) into eqn (A.2):
2
p
L
i
¼
2
p
L
o
d
i
2
d
o
2
(A
:
6)
After simplification of eqn (A.6):
r
L
i
L
o
d
o
¼
d
i
(A
:
7)
As length of microfilament is equivalent to distance travelled:
L
i
¼
v
i
t
(A.8)
L
o
¼
v
o
t
(A.9)
where t is time.
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