Influence of the Processes Parameters on the Properties of The ...
Influence of the Processes Parameters on the Properties of The ...
Influence of the Processes Parameters on the Properties of The ...
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Chapter 5.<br />
Characterizati<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> Scaffolds for C<strong>on</strong>nective Tissue Engineering<br />
SCION ® image analysis <str<strong>on</strong>g>of</str<strong>on</strong>g> SEM micrograph was d<strong>on</strong>e for each c<strong>on</strong>diti<strong>on</strong>. No macro pores were<br />
observed for sample A1 due to high dP/dt, A4 due to low T sat . For <str<strong>on</strong>g>the</str<strong>on</strong>g> o<str<strong>on</strong>g>the</str<strong>on</strong>g>r samples in A2, A5, A6, A8,<br />
A10, A11 and A12 macro pores had average diameter above 275m. A13 had maximum macro pores <str<strong>on</strong>g>of</str<strong>on</strong>g><br />
diameter 298 m al<strong>on</strong>g micro and meso pores. It was quite difficult to maintain 35 o C <str<strong>on</strong>g>of</str<strong>on</strong>g> temperature during<br />
<str<strong>on</strong>g>the</str<strong>on</strong>g> experimentati<strong>on</strong>. Because <str<strong>on</strong>g>of</str<strong>on</strong>g> temperature variati<strong>on</strong>s, we had to repeat <str<strong>on</strong>g>the</str<strong>on</strong>g> experiments thrice to attain T sat ,<br />
data <str<strong>on</strong>g>of</str<strong>on</strong>g> all <str<strong>on</strong>g>the</str<strong>on</strong>g> samples were recorded for calculati<strong>on</strong>s and analysis.<br />
Figure 5.33 and Figure 5.34 reveal that samples A3 and A9 produce pores <str<strong>on</strong>g>of</str<strong>on</strong>g> diameter ~200μm<br />
while samples with higher macro pore diameter produced cell density above 1×10 3 , while cell densities for<br />
micro and meso pores are also satisfactory.<br />
Figure 5.35 compares <str<strong>on</strong>g>the</str<strong>on</strong>g> % <str<strong>on</strong>g>of</str<strong>on</strong>g> surface area <str<strong>on</strong>g>of</str<strong>on</strong>g> three types <str<strong>on</strong>g>of</str<strong>on</strong>g> pores. We can see that samples A2,<br />
A5, A6, A7, A8, A10, A11 and A12 c<strong>on</strong>sist <str<strong>on</strong>g>of</str<strong>on</strong>g> more than 80% <str<strong>on</strong>g>of</str<strong>on</strong>g> surface area <str<strong>on</strong>g>of</str<strong>on</strong>g> macro pores produced. In<br />
A2,A11 and A12 <str<strong>on</strong>g>the</str<strong>on</strong>g> percentage is above 95%. <strong>The</strong>se three foams are quite close to each o<str<strong>on</strong>g>the</str<strong>on</strong>g>r. In o<str<strong>on</strong>g>the</str<strong>on</strong>g>rs<br />
cases, <str<strong>on</strong>g>the</str<strong>on</strong>g>re are variati<strong>on</strong>s in <str<strong>on</strong>g>the</str<strong>on</strong>g> three types <str<strong>on</strong>g>of</str<strong>on</strong>g> pore distributi<strong>on</strong>.<br />
Figure 5.36 reveals <str<strong>on</strong>g>the</str<strong>on</strong>g> optimum values <str<strong>on</strong>g>of</str<strong>on</strong>g> process parameters at which pores <str<strong>on</strong>g>of</str<strong>on</strong>g> maximum<br />
diameters can be produced. In our finding with PLGA 50:50 , we have found that a combinati<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g>, T sat =<br />
37.5°C, P sat = 120 bars, t sat = 25 min, and dP/dt = 3 bar/s, produce scaffold <str<strong>on</strong>g>of</str<strong>on</strong>g> optimum porosity, cell density<br />
and pore distributi<strong>on</strong>.<br />
Pore Diameter ( d e ) m<br />
400<br />
300<br />
200<br />
100<br />
Micro Pores Pore Variati<strong>on</strong> in Foam<br />
Meso Pores<br />
Macro Pores<br />
Cell Density-Pores / (cm) 3<br />
10 7 Micro Pores<br />
Meso Pores<br />
Macro Pores<br />
10 6<br />
10 5<br />
10 4<br />
Cell Density <str<strong>on</strong>g>of</str<strong>on</strong>g> Pores<br />
0<br />
A1<br />
A2<br />
A3<br />
A4<br />
A5<br />
A6<br />
A7<br />
A8<br />
A9<br />
PLGA 50:50<br />
Foams<br />
A10<br />
A11<br />
A12<br />
10 3<br />
A1 A2 A3 A4 A5 A6 A7 A8 A9 A10 A11 A12<br />
PLGA 50:50<br />
Foams<br />
Figure 5.33: Distributi<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> pores at different<br />
process c<strong>on</strong>diti<strong>on</strong>.<br />
Figure 5.34: Cell densities <str<strong>on</strong>g>of</str<strong>on</strong>g> pores produced at<br />
different process c<strong>on</strong>diti<strong>on</strong>.<br />
Pore Surface Area (%)<br />
100<br />
80<br />
60<br />
40<br />
20<br />
0<br />
Micro Pores<br />
Area Distributi<strong>on</strong> Meso Pores <str<strong>on</strong>g>of</str<strong>on</strong>g> Pores<br />
Macro Pores<br />
A1<br />
A2<br />
A3<br />
A4<br />
A5<br />
A6<br />
A7<br />
A8<br />
A9<br />
A10<br />
A11<br />
A12<br />
PLGA 50:50 Foams<br />
Pore Diameter ( d e ) m<br />
300<br />
250<br />
200<br />
150<br />
100<br />
50<br />
0<br />
35<br />
Tsat (°C)<br />
32.5<br />
PLGA 50:50<br />
Optimum <str<strong>on</strong>g>Parameters</str<strong>on</strong>g><br />
37.5<br />
Psat (bar)<br />
110<br />
120<br />
130<br />
tsat (min)<br />
15'<br />
20'<br />
25'<br />
dP/dt (bar/s)<br />
Process C<strong>on</strong>diti<strong>on</strong> [T sat -P sat -t sat -dP/dt]<br />
2<br />
3<br />
4<br />
Figure 5.35: Percentage <str<strong>on</strong>g>of</str<strong>on</strong>g> surface area for<br />
distributi<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> pores.<br />
Figure 5.36: Effective pore diameter for each<br />
process parameter.<br />
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