Environmental Engineering Reference
In-Depth Information
model of fracture mechanics, where the pull-off force (F) required to remove a rigid
cylindrical stud of radius, a, forms a ilm of thickness, h, is given by
Equation 2.1
:
F = πa
2
(2WK/h)
½
(2.1)
Where: W is the work of adhesion or the energy per unit area required to separate
the interface and K is the bulk modulus of the ilm, which is related to its Young's
modulus, E, by
Equation 2.2
:
K = E/(3(1-2n))
(2.2)
Where, n is Poisson's ratio.
This equation applies only when contact radius is much larger than the thickness of
the ilm. For a contact radius (a) less than the thickness (a < h) of the ilm, the pull-off
force is independent of thickness, and is given by the
Equation 2.3
[53]:
F= (8πa
3
WE/(1-v
2
))
½
(2.3)
Where E is Young's modulus
Studies on hard fouling organisms have shown that the thickness of the coating,
inluences its release [54].
2.4.1.7 Colour
Another important factor that inluences the community development is the colour
of the polymer surface. The difference in colour may impact on the short-term
development of biofouling communities. Dahlem and co-workers [55] found that black
acrylic coated polyvinyl chloride (PVC) panels showed higher settlement of marine
fouling larvae when compared to non-coated PVC panels. Swain and co-workers [56]
