Self-healable epoxy coatings reinforced with recycled carbon fibres
Topic(s) : Multifunctional and smart composites
Co-authors :
Pablo VAZQUEZ SANCHEZ (SPAIN)Abstract :
The aim is to develop organic coatings on polymer matrix composite material based on thermostable/thermoplastic blends (TS/TP) that allow self-healing by fusion of the thermoplastic dispersed phase. The development of these thermostable/thermoplastic blends is based on three fundamental axes: the recycling of Carbon Fiber reinforced polymer, self-healable coatings, and the development of heating techniques avoiding the traditional convection technologies such as autoclave or oven.
The self-healable epoxy coatings have been developed using polycaprolactone (PCL) as a thermoplastic repair agent. PCL/epoxy blend is obtained by Reaction Induced Phase Separation (RIPS) as an epoxy matrix with a well-dispersed spheric PCL phase, whose micro-scaled size depends on the PCL content, varying from 10 to 20 wt %.
The self-healing mechanism is triggered by thermal treatment above 110 ºC, where the PCL melts, flows, and can fill the crack. This thermal activation is induced electrically by the Joule effect. To generate the Joule effect heating, mechanically recycled carbon fibers (r-CF) are added to increase the electrical conductivity of the coating. The r-CF content varies from 10 to 30 wt % to reach the electrical percolation.
Additionally, several thermal and electrical treatments of the recycled carbon fiber are explored in order to improve the electrical behavior of the epoxy blend and allow a reduction of the carbon fiber weight percentage to only 3% to obtain similar conductivity and healing results.
Finally, the optimization of the mechanical recycling treatment of Carbon Fibre Reinforced Polymers (CFRP) has been made using two different types of materials, a SoA CFRP and a next-generation CFRP under development. Milling time and steps, and the consecutive sieved have been optimized to obtain different r-CF fractions with different average lengths and distributions.
The r-CF obtained will be analyzed by Optical Microscopy (OM) and subsequent image analysis, to know the average length and size distribution of the r-CF; BET to know its specific surface; X-ray Diffraction (XRD) and Raman Spectroscopy to evaluate the possible surface defects generated, Thermogravimetry (TGA), to determine the residual resin content and Scanning Electron Microscopy (SEM), to observe the state and morphology of the recycled product
All process and material variables have been characterized at the lab level to determine the right balance to get the highest self-healing capability in order to be developed for industrial applications in the aerospace industry.
The self-healable epoxy coatings have been developed using polycaprolactone (PCL) as a thermoplastic repair agent. PCL/epoxy blend is obtained by Reaction Induced Phase Separation (RIPS) as an epoxy matrix with a well-dispersed spheric PCL phase, whose micro-scaled size depends on the PCL content, varying from 10 to 20 wt %.
The self-healing mechanism is triggered by thermal treatment above 110 ºC, where the PCL melts, flows, and can fill the crack. This thermal activation is induced electrically by the Joule effect. To generate the Joule effect heating, mechanically recycled carbon fibers (r-CF) are added to increase the electrical conductivity of the coating. The r-CF content varies from 10 to 30 wt % to reach the electrical percolation.
Additionally, several thermal and electrical treatments of the recycled carbon fiber are explored in order to improve the electrical behavior of the epoxy blend and allow a reduction of the carbon fiber weight percentage to only 3% to obtain similar conductivity and healing results.
Finally, the optimization of the mechanical recycling treatment of Carbon Fibre Reinforced Polymers (CFRP) has been made using two different types of materials, a SoA CFRP and a next-generation CFRP under development. Milling time and steps, and the consecutive sieved have been optimized to obtain different r-CF fractions with different average lengths and distributions.
The r-CF obtained will be analyzed by Optical Microscopy (OM) and subsequent image analysis, to know the average length and size distribution of the r-CF; BET to know its specific surface; X-ray Diffraction (XRD) and Raman Spectroscopy to evaluate the possible surface defects generated, Thermogravimetry (TGA), to determine the residual resin content and Scanning Electron Microscopy (SEM), to observe the state and morphology of the recycled product
All process and material variables have been characterized at the lab level to determine the right balance to get the highest self-healing capability in order to be developed for industrial applications in the aerospace industry.