UNRAVELING THE POTENTIALITY OF INTRINSIC SELF-HEALING POLYAMIDE6/CYCLIC OLEFINIC COPOLYMER MATRIX IN CARBON FIBER REINFORCED COMPOSITES
Topic(s) : Multifunctional and smart composites
Co-authors :
Davide PERIN (ITALY), Andrea DORIGATO (ITALY), Alessandro PEGORETTI (ITALY)Abstract :
One of the heaviest limitations of composite materials is failure due to fatigue crack propagation during service. Repairing operations are time-consuming, poorly effective, and labor intensive. For these reasons, researchers and industries have recently shifted their interest toward a new generation of multifunctional composites with self-healing properties. The potentialities of self-healing composites are numerous such as the minimization of costs correlated to maintenance and repair operations, and the enhancement of the service life, thus improving the overall sustainability of these materials [1]. One of the most studied types of self-healing is intrinsic self-healing, in which the polymers can heal micro-damage like cracks under external stimuli.
At this aim, this work is focused on the production of both short and long-carbon fiber reinforced composites in which the self-healing action can be obtained through the use of an optimized self-healing thermoplastic matrix composed of compatibilized cyclic olefinic copolymer (COC) and polyamide 6 (PA6) [2]. The prepared composites will be able, through an external stimulus, to heal micro-damage in the proximity of the damage site thus prolonging the service life.
Short carbon fiber (6 mm) reinforced composites were produced by using a twin-screw extruder and subsequently, through injection molding. Long-carbon fiber (0/90° Carbon fiber 200g/m²) reinforced composites were prepared by film staking and subsequently hot pressing of 10 plies of carbon fiber and 11 thin films of self-healing matrix. To assess the self-healing behavior of the prepared composites, different types of tests were carried out, in particular, fracture toughness and Charpy impact tests. In addition, following a new methodology proposed by Hostettler et al. [3], tensile and 3-point bending fatigue tests were conducted to obtain the Wöhler curve. Following their methodology, it was possible to determine the survival curves for the prepared composites thus enabling the selection of a suitable loading level for introducing a specific amount of damage. By testing the composites at the selected load level and performing a healing cycle, it was possible to assess the beneficial advantage of the self-healing system in comparison to the reference system. Short carbon fiber reinforced composites with self-healing matrix reported limited healing efficiency (HE) considering the fracture toughness (5%), while by comparing the Charpy impact tests HE of approximately 50 % was obtained. By performing the tensile fatigue testing and the subsequent cycles to evaluate the healing performances, self-healing short carbon fiber reinforced composites were characterized by an enhanced fatigue life of approximately 50 %, while the reference was not affected by the same healing cycle. In conclusion, the intrinsic self-healing composite showed promising results and further efforts will be made in the future to improve the overall efficiency.
At this aim, this work is focused on the production of both short and long-carbon fiber reinforced composites in which the self-healing action can be obtained through the use of an optimized self-healing thermoplastic matrix composed of compatibilized cyclic olefinic copolymer (COC) and polyamide 6 (PA6) [2]. The prepared composites will be able, through an external stimulus, to heal micro-damage in the proximity of the damage site thus prolonging the service life.
Short carbon fiber (6 mm) reinforced composites were produced by using a twin-screw extruder and subsequently, through injection molding. Long-carbon fiber (0/90° Carbon fiber 200g/m²) reinforced composites were prepared by film staking and subsequently hot pressing of 10 plies of carbon fiber and 11 thin films of self-healing matrix. To assess the self-healing behavior of the prepared composites, different types of tests were carried out, in particular, fracture toughness and Charpy impact tests. In addition, following a new methodology proposed by Hostettler et al. [3], tensile and 3-point bending fatigue tests were conducted to obtain the Wöhler curve. Following their methodology, it was possible to determine the survival curves for the prepared composites thus enabling the selection of a suitable loading level for introducing a specific amount of damage. By testing the composites at the selected load level and performing a healing cycle, it was possible to assess the beneficial advantage of the self-healing system in comparison to the reference system. Short carbon fiber reinforced composites with self-healing matrix reported limited healing efficiency (HE) considering the fracture toughness (5%), while by comparing the Charpy impact tests HE of approximately 50 % was obtained. By performing the tensile fatigue testing and the subsequent cycles to evaluate the healing performances, self-healing short carbon fiber reinforced composites were characterized by an enhanced fatigue life of approximately 50 %, while the reference was not affected by the same healing cycle. In conclusion, the intrinsic self-healing composite showed promising results and further efforts will be made in the future to improve the overall efficiency.