Tensile Properties

Micro- or Nano-scale reinforcements are attractive for enhancing the tensile properties of syntactic foams. Glass and carbon fiber reinforcement was found to increase tensile strength and modulus of syntactic foams when compared to that of plain syntactic foam. The orientation of fibers with respect to the loading axis had a significant impact over the level of increase in the mechanical properties. However, reinforcement of microfibers increases the density of composite, which may be undesired in most applications; therefore, only a small volume fraction of fibers is used in syntactic foams. Carbon nanofiber (CNF) reinforcement increased the tensile strength and modulus of the syntactic foam. More specifically, addition of 0.25 wt% of CNFs increased, tensile modulus and strength of syntactic foams by 10–20 and 20–50 % (depending on the hollow particle wall thickness and volume fraction), respectively, when compared to that of plain syntactic foam. Nanoclay reinforcement was also found to increase the tensile strength and tensile modulus of syntactic foams in most studies. Nanofillers may have an undesired effect of stabilizing matrix porosity in syntactic foams during manufacturing. However, presence of nanoparticles around or across the matrix voids may provide a strengthening effect and the matrix porosity can be used to further decrease the syntactic foam density without a severe penalty on mechanical properties.