Page 28 - Engineered Interfaces in Fiber Reinforced Composites
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Chapter 2. Characterization of interfaces
Fig. 2.3. Capillary rise, showing the contact angle, 0, and height of meniscus, h
where yd represents the contribution due to London dispersion forces, which are
common to all materials, and yp relates to the polar contribution largely consisting
of hydrogen bonding and dipole-dipole interactions. When there is negligible
adsorption of the liquid-vapor phase onto the solid surface (Le. ysv = y,) and a
liquid adsorbs its own (i.e. yLv = yL), the surface tension at the solid/liquid interface
is given by (Owen and Wendt, 1969)
The above equation can be used to determine the total surface tension of a low
energy solid from a single contact angle measurement (Neumann et al., 1974). If the
liquid is chemically inert with respect to the solid
(2.10)
Combining Eq. (2.10) with Eq. (2.2) leads to
from which ysv can be derived for different values of the contact angle obtained for
a liquid of given yLv (Neumann et al., 1980).
