Roles of interfaces on microstructural and structural integrity of advanced FRP and nano-fillers enhanced multiscales FRP composites

Abstract

The interfaces of composite materials play an important role to sustain the structural integrity of the system. It has only been during the last few decades that applications of FRPs have become so rapidly growing that tailoring the well-bonded and durable interfaces has become a curious concern. An uncontrolled and non-uniform degradation at micro- and macro-levels manifests in the interphase because of different environmental conditions during service life. These may restrain its uses in the short term and also in the long-term reliability of the material. The predicted mechanical behaviour may alter during service life because of changes in the nature of the interface. Any changes in the interface might have substantial implications on its performances. The precise mode of failure is a function of the status of environmentally conditioned interfaces and time of exposure, thus complicating the prediction of its performances and behaviour. The interface is the most highly stressed region of composite materials. The important roles of interface necessitate a critical and comprehensive understanding of environmentally conditioned interfaces in FRP composite systems. It is reasonably assumed, the molecular structure here is dynamic in nature at the interfacial area, which is different from the bulk polymer matrix. The changes occurring at the interface are highly sensitive and susceptible to degradations under different environmental conditionings. Since the interphase is a region of chemical inhomogeneity, thus it provides an easy path of the system for becoming more susceptible to thermal, chemical, thermochemical and mechano-chemical degradations. Interfacial durability is a primary factor because environments to which the FRP composite is exposed can degrade interfacial adhesion as well as properties of the materials as a whole. The development of glass, carbon and aramid organic fibre reinforced polymeric composites is the beginning of an era of new light weight and durable structural composite materials. Advancements in reinforced polymer composites have gained preferential attention in recent days for high performance and high precision functional and structural applications including aerospace, automobile, marine, sports equipment, bridges, buildings and so on. The most attractive attribute of these polymer composite materials lies in its superior specific properties (e.g. strength to weight ratio and modulus to weight ratio) in conjunction with good impact strength, corrosion resistance, fatigue durability and damping characteristics which motivates engineers to use these materials in a wide spectrum of diversified applications. The key target in designing a polymer composite with CNTs is to replicate the extra-ordinary properties of the CNTs in the composite materials.