The cyclic-fatigue behaviour of an epoxy polymer modified with micron-rubber and nano-silica particles

Fibre-reinforced plastic (FRP) composites are widely used in ship hull, airframe and wind turbine structural applications where they are subjected to various types of constant and variable amplitude cyclic-fatigue loads. Hence, fatiguedurability is one of the important requirements for such composite materials. These FRPs, generally, contain continuous fibres of carbon or glass reinforced in a thermosetting epoxy-polymer matrix. The epoxy polymers are amorphous and highly cross-linked materials, because of which they have many useful structural properties such as a high modulus and failure strength, good creep resistance, good thermal properties, etc. However, they are relatively brittle and have poor resistance to crack initiation and growth. This, in turn, may adversely affect the overall performance of the FRPs under static and cyclic-fatigue loads. The addition of micron-rubber and nano-silica particles in the epoxy polymer has been shown to impart significant improvements in the mechanical properties of epoxies and FRPs [1–7]. However, investigations related to cyclicfatigue behaviour on particle-modified epoxies are rather limited and, in particular, fatigue studies on ‘hybrid’ epoxies containing both types of these particles are not available. This letter addresses the tensile fatigue behaviour of micron-rubber and nano-silica particle modified epoxy polymers, and describes some very novel and exciting observations.