Influence of the Processes Parameters on the Properties of The ...

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2.3 PLGA 85:15 Foams Processed by Wet and Dry Methods: Initial Taguchi’ Plan .................................................... 166 2.3.1 Effect <strong>of</strong> Process <strong>Parameters</strong> on Equivalent Pore Diameter (d e ) ............................................................... 167 2.3.2 Effect <strong>of</strong> Process <strong>Parameters</strong> on Geometric Porosity ................................................................................ 168 2.4 PLGA 85:15 Foams by Wet and Dry Methods by Complementary Taguchi Plan .................................................. 169 2.4.1 Effect <strong>of</strong> Process <strong>Parameters</strong> on Equivalent Pore Diameter (d e ) ............................................................... 170 2.4.2 Effect <strong>of</strong> Process <strong>Parameters</strong> on Geometric Porosity ................................................................................ 171 2.5 Comparison Between Both PLGAs ..................................................................................................................... 171 2.6 Pore Morphology and Anisotropy <strong>of</strong> Foams by Both Methods ........................................................................... 173 2.7 Interconnectivity <strong>of</strong> Pores in Foams by Both Methods ........................................................................................ 176 2.8 Mechanical Properties <strong>of</strong> <strong>the</strong> Foams by Wet and Dry Methods .......................................................................... 178 2.9 General Discussion .............................................................................................................................................. 178 3 Modification <strong>of</strong> <strong>the</strong> Surface by Adding Hyaluronic Acid .......................................................................... 179 3.1 Granulometry Analysis <strong>of</strong> PLGA and HA Before and After Co-grinding ........................................................... 179 3.2 Contact Angle Measurement and Surface Energy on Pellets ............................................................................... 181 3.2.1 Results ....................................................................................................................................................... 181 3.2.1.1 Contact Angles with Water and Pellets <strong>of</strong> PLGA, HA and PLGA/HA Blends .............................. 181 3.2.1.2 Surface Energy <strong>of</strong> PLGA, HA and PLGA/HA blends ................................................................... 182 3.2.2 Origin <strong>of</strong> <strong>the</strong> Increase <strong>of</strong> Surface Energy .................................................................................................. 183 4 Foams <strong>of</strong> PLGA 85:15 /HA Blends ................................................................................................................. 185 4.1 Preparation <strong>of</strong> Pellets ........................................................................................................................................... 185 4.2 Effect <strong>of</strong> scCO 2 <strong>Parameters</strong> on <strong>the</strong> Microstucture <strong>of</strong> Foams ............................................................................... 185 4.2.1 Effect <strong>of</strong> Depressurization Rate on <strong>the</strong> Microstucture <strong>of</strong> Foams .............................................................. 185 4.2.2 Effect <strong>of</strong> Saturation Temperature on <strong>the</strong> Microstucture <strong>of</strong> Foams ............................................................ 187 5 General Discussion ..................................................................................................................................... 188 6 Conclusion .................................................................................................................................................. 189 Chapter 7 ...................................................................................................................................................... 190 1 Characterization <strong>of</strong> Composites ................................................................................................................. 190 1.1 Fillers and Adjuvant ............................................................................................................................................ 190 1.1.1 Sr Calcium Phosphate ............................................................................................................................... 191 1.1.1.1 Syn<strong>the</strong>sis and Characterization <strong>of</strong> Calcium Phophates .................................................................. 191 1.1.1.2 Calcium Phosphate Characterization .............................................................................................. 191 1.1.1.3 Calcium Phosphate Granulometry .................................................................................................. 193 1.2 Adjuvant: Porogen Agent .................................................................................................................................... 194 1.2.1 Industrial Waxes ....................................................................................................................................... 194 1.2.2 Thermal Degradation ................................................................................................................................ 195 2 Experiments on Polylactides/Tri-calcium Phosphate Scaffolds ................................................................. 195 2.2 Experiments on Polylactides/Tri-calcium Phosphate ........................................................................................... 195 2.3 Analysis <strong>of</strong> Experiments on Polylactides/Tri-calcium Phosphate ....................................................................... 197 3 Foams <strong>of</strong> Polylactides/Calcium Phosphates Blends and Composites ........................................................ 198 - xvii -
3.2 Experiments on PLA/Waxes Scaffolds ............................................................................................................... 198 3.2.1 Preliminary Experimentation with Wax as Porogen Agent ...................................................................... 198 3.2.2 SEM Analysis <strong>of</strong> Foams ........................................................................................................................... 199 3.2.3 Effect <strong>of</strong> Wax on <strong>the</strong> Equivalent Pore Size and Geometric Porosity ........................................................ 201 3.3 Experiments on Polylactides/Tri-Calcium Phosphate/Wax Scaffolds ................................................................. 203 3.3.1 Effect <strong>of</strong> <strong>the</strong> Ratio <strong>of</strong> Wax on <strong>the</strong> Geometric Porosity and Equivalent Pore Size .................................... 203 3.3.2 Effect <strong>of</strong> Co-grinding Filler and PLGA on <strong>the</strong> Pore Morphology ............................................................ 205 3.4 Complementary Experiments on PLGA 85:15 /Tri-calcium Phosphate/Wax Scaffolds .......................................... 206 4 Conclusion .................................................................................................................................................. 209 Chapter 8 ...................................................................................................................................................... 210 1 Semi-industrial Production <strong>of</strong> Bone Scaffolds ........................................................................................... 210 1.1 Matrix: Polylactides............................................................................................................................................. 211 1.1.1 Experiments with Different Polylactides .................................................................................................. 211 1.1.2 Polylactide with Higher D,L Contents ...................................................................................................... 212 1.2 Effect <strong>of</strong> Polymer Particle Size on Foaming ....................................................................................................... 213 1.2.1 Foaming <strong>of</strong> PLGA 85:15 with Different Particle Size .................................................................................. 214 2 Filler: Tri-calcium phosphate Doped by Sr ................................................................................................ 215 2.1 Experimentation on Blends and Composite Foams ............................................................................................. 215 2.1.1 Experimentation on Composite Foaming with Different Co-grinding Times .......................................... 216 2.1.2 Foaming <strong>of</strong> Fine Powder and Filler Blend by Simple Mixing .................................................................. 217 2.1.3 Mixing Experimentation on Composite Foaming with Different Polymer Particle Size .......................... 218 3 Process Control for Composite Foaming .................................................................................................... 220 3.1 Semi-Industrial Foaming ..................................................................................................................................... 220 3.1.1 Pellet Positions in scCO 2 Chamber ........................................................................................................... 220 3.2 Final Experiments ................................................................................................................................................ 222 3.2.1 Multi Pellet Formation in a Batch and Effect on Foaming ....................................................................... 222 3.2.2 Preparation <strong>of</strong> Foams ................................................................................................................................ 224 3.2.2.1 Filling, Soaking and Depressurization Time <strong>of</strong> CO 2 in Chamber .................................................. 224 3.2.2.2 Temperature Variation During Soaking <strong>of</strong> CO 2 ............................................................................. 224 3.2.2.3 Dual Depressurization Rate............................................................................................................ 225 3.2.2.4 Temperature Variation During Depressurization <strong>of</strong> CO 2 ............................................................... 225 3.2.2.5 Retention Time after <strong>the</strong> Depressurization Step ............................................................................. 225 3.2.3 Final foam experiments ............................................................................................................................ 225 3.2.4 Discussion on <strong>the</strong> Rugdness <strong>of</strong> <strong>the</strong> Process .............................................................................................. 226 4 Mechanical Properties <strong>of</strong> Scaffolds ............................................................................................................ 229 4.1 Mechanical Characteristics <strong>of</strong> PLGA 85:15 Foam .................................................................................................. 229 4.2 Compressive Properties <strong>of</strong> Optimized PLGA 85:15 Composite Foams .................................................................. 231 4.3 Co-grinding time Effect on Compressive Properties <strong>of</strong> Composite Foams ......................................................... 231 4.4 Effect <strong>of</strong> Different Fillers and Wax-A Ratio on Compressive Properties <strong>of</strong> PLGA 85:15 Composite Foam .......... 232 5 Interconnectivity <strong>of</strong> Pores by CT ............................................................................................................ 233 5.1 PLGA 85:15 Scaffold .............................................................................................................................................. 233 5.2 PLGA 85:15 Composite Scaffold ............................................................................................................................ 235 - xviii -
Page 1 and 2: Institut National Polytechnique de
Page 4: iii Dedicated to My Fathe</
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Chapter 2. Processes</stron
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