Tensile properties of carbon nanofiber reinforced multiscale syntactic foams

The mechanical behavior of hollow glass microballoon-epoxy matrix syntactic foams reinforced with carbon nanofibers (CNFs) is studied in this work. Glass microballoons of two different wall thicknesses are used in two volume fractions to obtain four types of CNF reinforced syntactic foams. Tensile test results show that the presence of CNFs leads to increased values of strength and modulus in syntactic foams containing 50 vol.% microballoons compared to unreinforced syntactic foams. The specific tensile modulus of all CNF reinforced composites is found to be higher than that of the CNF reinforced epoxy resin used as the matrix. Fracture surfaces of CNF/epoxy and CNF reinforced syntactic foams show extensive deformation marks. Instrumented nanoindentation tests are conducted on CNF/epoxy specimens to further characterize the elastic properties of the reinforced resin matrix. A homogenization technique based on the so-called differential scheme that accounts for particle size and wall thickness polydispersivity along with entrapped matrix voids is used to interpret experimental results. The model predictions are in close agreement with the experimental results. (C) 2012 Elsevier Ltd. All rights reserved.