Multi-functional self-healing materials for structural application

Abstract

Main objective of this PhD thesis is the development of a new generation of self-healing multifunctional composites able to overcome some of the current limitations of aeronautical materials, such as: absence of auto-repair mechanisms integrated in the composite structure, reduced electrical conductivity and poor impact damage resistance. Structural aeronautical systems experience a broad spectrum of environmental and operational loads and atmospheric hazards (hail, lightning, storms etc.). Severe and/or prolonged load exposures may trigger the damage accumulation process even in recently deployed structures. Modern airframe design is exploiting new exciting developments in materials and structures to construct ever more efficient air vehicle able to enable ‘smart’ maintenance including self-repair capabilities. Relevant challenges for many of the already developed self-repairing systems are to enhance the structural stability, and the resistance to the atmospheric hazards through specific functions integrated in the material. The traditional approach to the development of aeronautic materials is to address the load-carrying and other functional requirements separately, resulting in a suboptimal load-bearing material with the penalty of added weight. The research activity of this PhD thesis is aimed to develop self-healing, load-bearing materials with all functionalities integrated in a single material able to meet many important requirements of this kind of materials. The main concept underpinning this PhD project is the use of the nanotechnology strategy for the production of new, high mechanical performance multifunctional materials. Based on recent developments in the field of nanotechnologies and successful strategies identified in recently papers and patents, the main objectives of this thesis have been achieved. The performed research activities allowed the implementation of a new generation of self-healing composites, which also considers relevant aspects related to the need of developing environmentally-friendly materials for transports. In this project, many different approaches have been considered for each functionality in order to reduce the risk of failure. Alternative concepts with respect to designs already proposed in literature have been explored. Multifunctional resins prepared using chemicals not commercially available yet have been developed and characterized. ... [edited by Author]