Page 700 - Polymer-based Nanocomposites for Energy and Environmental Applications

Carbon nanotube-based nanocomposites for wind turbine applications 643

low concentration of CNTs can significantly affect the properties of nanocomposites.
FRPs are key materials for energy industry because of enhancing toughness, strength,
and other physical properties. To improve material properties, filler-filler and filler-
matrix interaction is critical, besides dispersion and alignment of the filler might be
further optimized for wind blades. The high cost of CNTs confines their application in
FRPs for blades. However, blend of CNTs with other fillers that have low cost such as
clay and carbon black presents alternative nanocomposites [4].

24.2.3 Electrostatic properties
Wind turbine rotor blades and aircraft wings are two examples for the application of
really high cycle of load and higher loads for a long lifetime that is nearly 30 years.
Due to that reason, mechanical properties and fatigue life are very important. In addi-
tion to mechanical properties, health monitoring became essential. B€ oger et al. [23]
studied health monitoring of glass fiber-reinforced composites by using carbon nano-
tube (CNT) and carbon black. First of all, epoxy resin was modified by using CNT to
make the composite electrically conductive. Then, glass fiber was used as a reinforce-
ment material, and resin transfer molding (RTM) technique was used for composite
fabrication. Incremental tensile test, fatigue test, and interlaminar shear strength
(ILSS) were determined. The electric conductivity of test specimens was monitored
during test procedure to determine the composite damage behavior. According to the
results, electric conductive resin presented high-potential usage for structural health
monitoring (SHM) [23].
Wind energy is a promising renewable energy system; however, it should be cost-
effective to compete with traditional energy systems. SHM is a good strategy to
decrease maintenance and operation costs. In addition to this, SHM is a good way
to predict damage before causing failure. Wind turbine blades are exposed to higher
and cycling loads, so health monitoring is really significant to monitor the effect of
loads. Mortensen et al. [24] worked on health monitoring of wind turbine blades
by using thin sensor film that was modified with CNT. Incorporating CNT makes
the thin films electrically conductive. Electric properties of the thin film are changing
under loads; thus, any damage, debonding, or discontinuities due to loading cause a
change in electromechanical properties. Therefore, a number of changes can help in
predicting structure failure [24].
Table 24.2 shows some studies on mechanical, electric, and thermal properties of
CNT-based nanocomposites.

24.3 Alternative nanocomposites for CNT-based
composites

Alternative nanocomposites that can replace CNT-based composites for wind turbine
applications have also presented as part of this book chapter. These nanocomposites
are based on nanoparticles such as nanosilica, nanoclay, and cellulose nanocrystals in
which their role is to control viscosities of resins during manufacturing essentially. In