Multifunctional materials Self-healing/self-sensing capabilities for wind blade turbines

Multifunctional materials Self-healing/self-sensing capabilities for wind blade turbines

The use of wind as a source of energy has increased extremely quick in the last decades, thus a 30% of growth worldwide has been reported. Since 2016, wind generators are the second source of power generation when it overtook coal industry which is well developed in European countries. Moreover, wind power installed in 2017 was greater than any other source of energy and the tendency is that the installation of this type of energy will grow during the next decade.

This growth will require the installation of wind turbines in more aggressive ambient, mainly sea and high erosive ambient because of the development of off-shore wind energy and the installation of wind turbines in high altitude and dessert areas, respectively. The erosion and wear of blade coatings in these environments will be much quicker and the maintenance operations will be even more difficult. Taking these aspects into account, the development of coatings and composite materials with improved mechanical resistance to increase the time between maintenance operations will be a key issue for these applications. The development of polymers with self-healing capabilities has attracted great interest during the last decades. Previous knowledge about thermosetting/thermoplastic blends has allowed developing materials with self-healing capabilities based on the flow of the thermoplastic component when the material is heated . All blends are not suitable as the thermoplastic must have enough flow capability at temperatures below the glass transition temperature of the thermosetting component to avoid damage of the structure or coating and good compatibility between them. Its flow will allow filling the cracks generated thus, allowing the materials being in service longer time without the need of costly maintenance operations.

Nevertheless, the installation of these materials present three main drawbacks to be overcame: heating source requirement, detection of damage to activate the external source and modification of the mechanical performance of the thermosetting matrix. The addition of carbon nanostructures in the polymer matrix is proposed as a way to overcome the three main challenges mentioned above by the development of ternary states based on thermosetting/thermoplastic/nanoreinforcement materials. The experience in the addition of carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs) has allowed developing multifunctional materials with self-sensing and self-heating capabilities and, consequently, their addition may help detecting the damage and generating the heat required for the healing of the crack. In addition, the mechanical performance is also improved with better interlaminar properties and wear/erosion resistance, among others. Proposed materials need special research in the manufacturing stage as the addition of the nanoreinforcement may cause different effects when added in the thermosetting, the thermoplastic or both blend components. When developed, the nanoreinforced matrices will be applied as self-healing/self-sensing coatings with improved erosion and wear resistance due to the presence of the carbon nanoparticles and, as nanoreinforced matrices, in multiscale reinforced composites containing glass fibers for the blade itself. The interest in this last application is very important as detection and healing of small cracks/delaminations of the composite materials is a key aspect of wind blades.