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 />
using <str<strong>on</strong>g>the</str<strong>on</strong>g> Mark-Houwink Relati<strong>on</strong>ship (MHR) with K = 2.2610 -5 dl/g and a = 0.796, <str<strong>on</strong>g>the</str<strong>on</strong>g> molecular weight<br />
we obtain: M vis = 2 637 540 g/mol.<br />
1.1.2 Discussi<strong>on</strong> <strong>on</strong> <str<strong>on</strong>g>the</str<strong>on</strong>g> Molecular Mass<br />
Experimental results have been compared with values given in data sheets with <str<strong>on</strong>g>the</str<strong>on</strong>g> different<br />
polylactides. All <str<strong>on</strong>g>the</str<strong>on</strong>g> values, reported <strong>on</strong> Table 5.4, are in <str<strong>on</strong>g>the</str<strong>on</strong>g> range <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g> specificati<strong>on</strong>s. Moreover, <str<strong>on</strong>g>the</str<strong>on</strong>g><br />
separati<strong>on</strong> between <str<strong>on</strong>g>the</str<strong>on</strong>g> two main medical applicati<strong>on</strong>s <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g> polylactides seems to be governed by <str<strong>on</strong>g>the</str<strong>on</strong>g><br />
intrinsic viscosity range <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g> polymers. Below a certain molecular mass (i.e. <str<strong>on</strong>g>the</str<strong>on</strong>g> critical mass), oligomers<br />
are used as c<strong>on</strong>trolled release and above this critical mass polymers can be used as medical device. As<br />
shown <strong>on</strong> Table 5.4, differences between polylactides <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g> same inherent viscosities range are not<br />
significant; <str<strong>on</strong>g>the</str<strong>on</strong>g>y can be chosen whatever <str<strong>on</strong>g>the</str<strong>on</strong>g>ir origin (Lactel, Purac, Boehringer).<br />
Table 5.4: Comparis<strong>on</strong> between molecular weight <str<strong>on</strong>g>of</str<strong>on</strong>g> various polylactides.<br />
Polylactides<br />
Data Sheet* Experiments M w Deduced<br />
inh (dL/g) inh (dL/g) from MHR<br />
Applicati<strong>on</strong>s<br />
P L,D LA (PABR L 68) 2.33 2.24 163 971 Packaging<br />
P L,DL LA (Resomer ® LR 704) 2.0 − 2.8 2.68 201 169 Medical device<br />
PLGA 85:15 (Resomer ® RG 858S) 1.3 − 1.7 1.62 57 529 C<strong>on</strong>trolled release<br />
PLGA 85:15 (DL-PLG) 0.55 − 0.75 0.72 18 943 C<strong>on</strong>trolled release<br />
PLGA 50:50 (PLG 8523) 2.27 2.21 88 033 Medical device<br />
PLGA 85:15 (PLG 8531) 3.11 2.96 131 366 Medical device<br />
PLGA 85:15 (LG 857 S) 5.0 − 7.0 6.63 396 495 Medical device<br />
PLGA 50:50 (Resomer ® RG 504) 0.45 − 0.60 0.59 14 756 C<strong>on</strong>trolled release<br />
PLGA 50:50 (PDLG 5010) 1.03 0.97 28 494 Medical device<br />
1.1.3 Characterizati<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> Polylactide Powders by DSC<br />
<strong>The</strong> <str<strong>on</strong>g>the</str<strong>on</strong>g>rmograms <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g> different PLAs and PLGAs are presented in <str<strong>on</strong>g>the</str<strong>on</strong>g> Figure 5.2, Figure 5.3 and<br />
Figure 5.4. <strong>The</strong> <str<strong>on</strong>g>the</str<strong>on</strong>g>rmograms are representative <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g> sec<strong>on</strong>d scan run.<br />
Figure 5.2: <strong>The</strong>rmograms <str<strong>on</strong>g>of</str<strong>on</strong>g> various PLAs.<br />
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