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 4.<br />
Experimental Procedures and Protocols for Analyses<br />
3 Protocols for Analysis<br />
3.1 Granulometry<br />
Experiments have been performed at <str<strong>on</strong>g>the</str<strong>on</strong>g> "Laboratoire de Génie Chimique de Toulouse"<br />
<strong>The</strong> s<str<strong>on</strong>g>of</str<strong>on</strong>g>tware proposed by Malvern with <str<strong>on</strong>g>the</str<strong>on</strong>g> granulometer Mastersizer 2000 uses <str<strong>on</strong>g>the</str<strong>on</strong>g> Mie<br />
<str<strong>on</strong>g>the</str<strong>on</strong>g>ory and permits to limit artefacts at small sizes <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g> size distributi<strong>on</strong>s. Experimentally, <str<strong>on</strong>g>the</str<strong>on</strong>g> particles pass<br />
through <str<strong>on</strong>g>the</str<strong>on</strong>g> Scirocco composed <str<strong>on</strong>g>of</str<strong>on</strong>g> a vibrating hopper where particles are placed. A compressed air supply<br />
is out <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g> hopper and creates depressi<strong>on</strong> causing <str<strong>on</strong>g>the</str<strong>on</strong>g> particles to <str<strong>on</strong>g>the</str<strong>on</strong>g> sensor. Vacuum allows <str<strong>on</strong>g>the</str<strong>on</strong>g> recovery<br />
<str<strong>on</strong>g>of</str<strong>on</strong>g> particles at <str<strong>on</strong>g>the</str<strong>on</strong>g> end <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g> circuit. <strong>The</strong> particles diffract light at an angle. A lens Fourier can be reduced<br />
into a single optical diffracting each source. Image result <str<strong>on</strong>g>of</str<strong>on</strong>g> diffracti<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> a light beam is a set <str<strong>on</strong>g>of</str<strong>on</strong>g> c<strong>on</strong>centric<br />
rings. <strong>The</strong> value <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g> deflecti<strong>on</strong> angle and <str<strong>on</strong>g>the</str<strong>on</strong>g> amount <str<strong>on</strong>g>of</str<strong>on</strong>g> light can be accessed respectively to particle size<br />
and quantity. <strong>The</strong> deflecti<strong>on</strong> angle <str<strong>on</strong>g>of</str<strong>on</strong>g> all smaller particles is large. <strong>The</strong> light diffracted by <str<strong>on</strong>g>the</str<strong>on</strong>g> sample is<br />
recorded which can be traced back to <str<strong>on</strong>g>the</str<strong>on</strong>g> size distributi<strong>on</strong>, and <str<strong>on</strong>g>the</str<strong>on</strong>g> percentage volume in each size class. <strong>The</strong><br />
size range available is between 0.05 and 2000 micr<strong>on</strong>s.<br />
Approximately a mass <str<strong>on</strong>g>of</str<strong>on</strong>g> 200 to 300 mg <str<strong>on</strong>g>of</str<strong>on</strong>g> powder material is placed inside <str<strong>on</strong>g>the</str<strong>on</strong>g> inlet pan. It tracks<br />
<str<strong>on</strong>g>the</str<strong>on</strong>g> evoluti<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> total grain size during milling. <strong>The</strong> parameters that affect <str<strong>on</strong>g>the</str<strong>on</strong>g> measure are <str<strong>on</strong>g>the</str<strong>on</strong>g> amplitude <str<strong>on</strong>g>of</str<strong>on</strong>g><br />
vibrati<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> hopper that c<strong>on</strong>trols <str<strong>on</strong>g>the</str<strong>on</strong>g> flow <str<strong>on</strong>g>of</str<strong>on</strong>g> particles introduced into <str<strong>on</strong>g>the</str<strong>on</strong>g> measuring cell and <str<strong>on</strong>g>the</str<strong>on</strong>g> pressure<br />
<str<strong>on</strong>g>of</str<strong>on</strong>g> compressed air that plays <strong>on</strong> <str<strong>on</strong>g>the</str<strong>on</strong>g> velocity <str<strong>on</strong>g>of</str<strong>on</strong>g> passage <str<strong>on</strong>g>of</str<strong>on</strong>g> particles to <str<strong>on</strong>g>the</str<strong>on</strong>g> laser beam. After various trials for<br />
analysis, we found better reproducibility <str<strong>on</strong>g>of</str<strong>on</strong>g> measurements for 70% <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g> maximum amplitude <str<strong>on</strong>g>of</str<strong>on</strong>g> vibrati<strong>on</strong><br />
<str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g> hopper and a pressure <str<strong>on</strong>g>of</str<strong>on</strong>g> 2 bars. Its measure range in dry dispersi<strong>on</strong> is 0.1 to 2 000 micr<strong>on</strong>s. Typical<br />
measurement time is 5 sec<strong>on</strong>ds.<br />
<strong>The</strong> size distributi<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> polymer powders after pre-treatment (just sieving or grinding in <str<strong>on</strong>g>the</str<strong>on</strong>g><br />
knife mill and sieving) are presented in Figure 4.17. Most <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g> particles <str<strong>on</strong>g>of</str<strong>on</strong>g> different materials used have<br />
mean diameter between 100 and 175m. <strong>The</strong> mean diameter (d 50 ) <str<strong>on</strong>g>of</str<strong>on</strong>g> a grinded polymer is 89.54 m.<br />
<strong>The</strong> median diameter (d 50 ) is a very important characteristic <str<strong>on</strong>g>of</str<strong>on</strong>g> this distributi<strong>on</strong> because it<br />
represents a cummulative frequency <str<strong>on</strong>g>of</str<strong>on</strong>g> 50%, which divides <str<strong>on</strong>g>the</str<strong>on</strong>g> size distributi<strong>on</strong> into two parts <str<strong>on</strong>g>of</str<strong>on</strong>g> equal area.<br />
This parameter permits to follow easily <str<strong>on</strong>g>the</str<strong>on</strong>g> evoluti<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> particle size during a treatment <str<strong>on</strong>g>of</str<strong>on</strong>g> a powder. As an<br />
illustrati<strong>on</strong>, Figure 4.18 presents <str<strong>on</strong>g>the</str<strong>on</strong>g> variati<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> median size <str<strong>on</strong>g>of</str<strong>on</strong>g> P L,D LA particles submitted to a grinding<br />
treatment in a tumbling ball mill.<br />
12<br />
10<br />
400<br />
Particle Diameter Variati<strong>on</strong> with Grinding time<br />
Volume (%)<br />
8<br />
6<br />
4<br />
2<br />
Poly (Lactide-co-glycolide) : Granulometry<br />
d 50 (m)<br />
300<br />
200<br />
100<br />
0<br />
0.01 0.1 1 10 100 1000 10000<br />
Particle Size(m)<br />
0<br />
0 1000 2000 3000 4000 5000<br />
Grinding Time (min)<br />
Figure 4.17: Size distributi<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> P L,D LA particle<br />
after 30 minutes <str<strong>on</strong>g>of</str<strong>on</strong>g> grinding.<br />
Figure 4.18: Variati<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> particle diameter with<br />
grinding time for P L,D LA<br />
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