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 />
Chapter 5<br />
Chapter<br />
5<br />
Characterizati<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g><br />
Scaffolds for<br />
C<strong>on</strong>nective Tissue<br />
Engineering<br />
In this chapter, we present characterizati<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> different biopolymers such as P L LA, P L,DL LA,<br />
PLGA 50:50 and PLGA 85:15 for a comparative study. Particular attenti<strong>on</strong> has been focused <strong>on</strong> amorphous and<br />
semi-crystalline polymers. <strong>The</strong> modelling <str<strong>on</strong>g>of</str<strong>on</strong>g> scCO 2 foaming <str<strong>on</strong>g>of</str<strong>on</strong>g> polymers by pressure quench method requires<br />
<str<strong>on</strong>g>the</str<strong>on</strong>g> resoluti<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g> diffusi<strong>on</strong> equati<strong>on</strong> as well as <str<strong>on</strong>g>the</str<strong>on</strong>g> degree <str<strong>on</strong>g>of</str<strong>on</strong>g> depressi<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g> glass transiti<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> polymer<br />
as a functi<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g> amount <str<strong>on</strong>g>of</str<strong>on</strong>g> CO 2 sorbed. Indeed, certain iso<str<strong>on</strong>g>the</str<strong>on</strong>g>rmal sorpti<strong>on</strong> data and its modelling are<br />
required for such study. In this chapter, after explaining <str<strong>on</strong>g>the</str<strong>on</strong>g> principles <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g> foaming phenomen<strong>on</strong><br />
precisely, we have focused <strong>on</strong> <str<strong>on</strong>g>the</str<strong>on</strong>g> resoluti<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> diffusi<strong>on</strong> equati<strong>on</strong>, <str<strong>on</strong>g>the</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g>rmodynamics <str<strong>on</strong>g>of</str<strong>on</strong>g> phase equilibrium,<br />
<str<strong>on</strong>g>the</str<strong>on</strong>g> depressi<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> T g as a functi<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g> CO 2 sorpti<strong>on</strong>. Finally, we have derived <str<strong>on</strong>g>the</str<strong>on</strong>g> nucleati<strong>on</strong> equati<strong>on</strong>,<br />
which is based <strong>on</strong> <str<strong>on</strong>g>the</str<strong>on</strong>g> use <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g> classical nucleati<strong>on</strong> <str<strong>on</strong>g>the</str<strong>on</strong>g>ory.<br />
<strong>The</strong>n characterizati<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g> foams obtained by supercritical CO 2 process by varying <str<strong>on</strong>g>the</str<strong>on</strong>g> ratios <str<strong>on</strong>g>of</str<strong>on</strong>g><br />
LA/GA c<strong>on</strong>tents were taken into account to correlate solubility <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g> scCO 2 <str<strong>on</strong>g>of</str<strong>on</strong>g> pellets and equivalent pore<br />
size and porosity in scaffolds. A focus <strong>on</strong> pore morphology, structure anisotropy and <str<strong>on</strong>g>the</str<strong>on</strong>g>ir characteristics<br />
will be emphasized as it plays an important role in cell seeding, differentiating and growth in <str<strong>on</strong>g>the</str<strong>on</strong>g> scaffold.<br />
1 Characterizati<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> Biomaterials<br />
1.1 Characterizati<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> Polylactide Powders<br />
All <str<strong>on</strong>g>the</str<strong>on</strong>g> polymers in powder form were used directly by sieving through 500 m mesh to avoid any<br />
foreign particles or agglomerate. O<str<strong>on</strong>g>the</str<strong>on</strong>g>rs in granules and pellet form were ground in knife mill as described<br />
in chapter 4. <strong>The</strong> physical appearance and compositi<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> each polymer is stated as under:<br />
P L,D LA (PABR L 68) is L,D polylactic acid c<strong>on</strong>taining approximately 12% <str<strong>on</strong>g>of</str<strong>on</strong>g> D-lactic acid. <strong>The</strong>y<br />
are available in brownish yellow granules form.<br />
P L,DL LA (LR 704) is a poly (L-lactide-co-D,L-lactide) with a L-lactide : D,L-lactide molar ratio <str<strong>on</strong>g>of</str<strong>on</strong>g><br />
67:33 to 73:27. It is white to <str<strong>on</strong>g>of</str<strong>on</strong>g>f-white granules.<br />
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