Tailored interphase for improved strength and energy absorption of composite
There is a great demand for fiber-reinforced polymeric composites in aircraft, automobiles, marine, infrastructure and other consumer applications. In the case of a composite bridge deck, high strength and long term durability is needed. Most of the research to date has focused on tailoring the interphase adhesion and durability by controlling the state and concentration of fiber surface functional groups through sizing to increase the degree of chemical bonding and to create attractive interactions, such as covalent bonds, hydrogen bonds, and intermolecular interactions between fiber and resin. The Interfacial Shear Strength (IFSS) has been increased by as much as 40% through modified chemical bonding. However, it is well known that optimizing the strength of the brittle fiber reinforced polymeric composite material often leads to a reduction in the fracture toughness and vice versa. There is always a tradeoff between achieving high interfacial shear strength and improving energy absorption by chemically modifying the fiber surface. Tailoring of the composite properties to satisfy strength, durability or energy absorption is important and can be done at various length scales starting at the fiber-matrix interphase. This research conducts a systematic study of tailoring fiber-matrix interphase structure through creating textures on the glass fiber surface, inducing the mechanical interlocking between fiber and matrix, investigating the effect of induced mechanical interlocking on composite properties, establishing a foundation for the microstructural design of a high impact-resistant composite and optimizing the composite’s structural and impact performance. Both micromechanical and macromechanical tests demonstrate the significant influence of tailoring the interphase structure on improving the impact performance of the composites.