Compressive Properties

Most existing applications of syntactic foams are based on their compressive properties. Hollow particles are load bearing elements in the syntactic foam microstructure under compression, which helps in obtaining a long stress plateau region in the stress–strain graphs that helps in obtaining high energy absorption. The available studies have extensively studied the effect of hollow particle wall thickness and volume fraction on compressive properties of syntactic foams. Similarly, reinforced syntactic foams have been extensively studied for compressive properties. Carbon nanofibers and nanotubes, nanoclay, crumb rubber and glass, and carbon fibers have been used as reinforcements in syntactic foams to tailor the compressive properties. The incorporation of CNFs increases the overall energy absorption capacity of the composite. Orientation of fibers with respect to the loading axis is important in obtaining strengthening effect and randomly dispersed fibers do not provide high level of increase in compressive properties. In some layered reinforced syntactic foams, fibers oriented parallel to loading direction enhanced their compressive strength by 180–220 % compared to that of plain syntactic foams. On the contrary, foams containing fiber orientation perpendicular to the loading direction showed no measurable change in strength. The strength and modulus increase with density for reinforced syntactic foams. The maximum compressive strength and modulus for reinforced syntactic foam were found to be 120 MPa and 2.2 GPa, respectively.