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 3.<br />
Analytical Methods and Designs <str<strong>on</strong>g>of</str<strong>on</strong>g> Experiments<br />
Andrade, 1985]. <strong>The</strong> Liquid-Vapour tensi<strong>on</strong> and <str<strong>on</strong>g>the</str<strong>on</strong>g> Solid-Vapour energy are generally approximated by <str<strong>on</strong>g>the</str<strong>on</strong>g><br />
liquid tensi<strong>on</strong> and <str<strong>on</strong>g>the</str<strong>on</strong>g> surface energy.<br />
Selected liquids need to have suitable properties in order to interact in <str<strong>on</strong>g>the</str<strong>on</strong>g> best possible way to<br />
determine <str<strong>on</strong>g>the</str<strong>on</strong>g> surface energy. Firstly, <str<strong>on</strong>g>the</str<strong>on</strong>g> liquids have to carry a wide range <str<strong>on</strong>g>of</str<strong>on</strong>g> intermolecular interacti<strong>on</strong>s<br />
from polar to apolar. In additi<strong>on</strong>, <str<strong>on</strong>g>the</str<strong>on</strong>g> liquid surface tensi<strong>on</strong> has to be higher than <str<strong>on</strong>g>the</str<strong>on</strong>g> solid surface energy: <str<strong>on</strong>g>the</str<strong>on</strong>g><br />
working forces <strong>on</strong> <str<strong>on</strong>g>the</str<strong>on</strong>g> surface <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g> solid sample are superior to <str<strong>on</strong>g>the</str<strong>on</strong>g> forces needed to create <str<strong>on</strong>g>the</str<strong>on</strong>g> drop,<br />
resulting in a high wettability. <strong>The</strong> latter makes it impossible to determine a c<strong>on</strong>tact angle [Mykhaylyk et al.,<br />
2003]. By drawing L (1+ cos)/( L d ) 1/2 versus ( L nd ) 1/2 /( L d ) 1/2 , <str<strong>on</strong>g>the</str<strong>on</strong>g> slope will be ( S nd ) 1/2 and <str<strong>on</strong>g>the</str<strong>on</strong>g> origin intercept<br />
will be ( S d ) 1/2 (cf. Figure 3.25).<br />
L<br />
(1+cos)/2.( L<br />
d ) 1/2<br />
12<br />
11<br />
10<br />
9<br />
8<br />
7<br />
6<br />
y = 3.0332 x + 5.8084<br />
R 2 = 0.8369<br />
Water<br />
Ethylene Glycol<br />
rom<strong>on</strong>aphtalene<br />
5<br />
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8<br />
( nd / d ) 1/2<br />
L L<br />
Figure 3.25: Example <str<strong>on</strong>g>of</str<strong>on</strong>g> determinati<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> surface energy comp<strong>on</strong>ents <str<strong>on</strong>g>of</str<strong>on</strong>g> a blend PLGA + 5 % HA<br />
with <str<strong>on</strong>g>the</str<strong>on</strong>g> Owens-Wendt’ method.<br />
In this model, <str<strong>on</strong>g>the</str<strong>on</strong>g> measure <str<strong>on</strong>g>of</str<strong>on</strong>g> c<strong>on</strong>tact angle between two different liquids and <str<strong>on</strong>g>the</str<strong>on</strong>g> solid is<br />
necessary to calculate <str<strong>on</strong>g>the</str<strong>on</strong>g> surface energy. However, it is an approximati<strong>on</strong> to c<strong>on</strong>sider that <str<strong>on</strong>g>the</str<strong>on</strong>g> solid surface<br />
energy is <str<strong>on</strong>g>the</str<strong>on</strong>g> simple geometrical mean <str<strong>on</strong>g>of</str<strong>on</strong>g> p S and d S (equati<strong>on</strong> 3.15). This approximati<strong>on</strong> can not predict <str<strong>on</strong>g>the</str<strong>on</strong>g><br />
behaviour <str<strong>on</strong>g>of</str<strong>on</strong>g> polar polymer in aqueous envir<strong>on</strong>ment.<br />
6.2.2.3 Model <str<strong>on</strong>g>of</str<strong>on</strong>g> Good-Van Oss : Three Comp<strong>on</strong>ents <strong>The</strong>ory<br />
In <str<strong>on</strong>g>the</str<strong>on</strong>g> model <str<strong>on</strong>g>of</str<strong>on</strong>g> Good-Van Oss [Owens and Wendt, 1969], surface energy is written:<br />
d <br />
S <br />
S<br />
2 ( <br />
S<br />
. S )<br />
(3.24)<br />
where γ S d is <str<strong>on</strong>g>the</str<strong>on</strong>g> dispersive comp<strong>on</strong>ent and γ S<br />
+<br />
and γ S - are <str<strong>on</strong>g>the</str<strong>on</strong>g> acid-base comp<strong>on</strong>ents respectively.<br />
Van Oss et al. [1988] proposed <str<strong>on</strong>g>the</str<strong>on</strong>g> so-called Lifshitz–Van der Waals approach in which <str<strong>on</strong>g>the</str<strong>on</strong>g> total<br />
surface tensi<strong>on</strong> is divided in Lifshitz–Van der Waals ( LW ) and acid-base ( AB ) comp<strong>on</strong>ents. <strong>The</strong> last <strong>on</strong>e is<br />
decomposed in acid ( + ) and basic ( - ) comp<strong>on</strong>ents. Young-Dupré equati<strong>on</strong> can be expressed as:<br />
( 1 cos ) G<br />
G<br />
(3.25)<br />
L<br />
LW<br />
SL<br />
AB<br />
SL<br />
where<br />
LW<br />
LW LW 1 / 2<br />
G<br />
SL<br />
2 ( <br />
S<br />
. <br />
L<br />
)<br />
(3.26)<br />
We may define <str<strong>on</strong>g>the</str<strong>on</strong>g> AcidBase free energy <str<strong>on</strong>g>of</str<strong>on</strong>g> interacti<strong>on</strong> between two substances in <str<strong>on</strong>g>the</str<strong>on</strong>g> c<strong>on</strong>densed<br />
state [van Oss et al., 1987].<br />
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