7. Flexural Properties

The flexural behavior has been studied only for a few reinforced syntactic foams. The short glass fiber reinforced epoxy matrix syntactic foams showed fiber pull out and hollow particle/matrix debonding as the main failure mechanisms under flexural loading conditions. Transition in the failure pattern was observed with the increase in the fiber content. Brittle failure was seen in syntactic foams containing less than 2 vol. % fibers, while foams containing 2–4.5 vol. % fibers showed fiber bending rather than complete failure. Silica particle (8–9 μm diameter) filled syntactic foams showed decreases in flexural strength and modulus with increasing silica content in the range 5–15 wt.%. It is found that the syntactic foams with 2 wt% nanoclay show the highest improvement in flexural properties, which include nearly 42 % and 18 % increase in strength and modulus, respectively. The flexural modulus and strength are extracted from the available studies on various reinforced syntactic foams and are plotted with respect to the density. The highest flexural strength and modulus values of any available reinforced syntactic foam are found to be 78 MPa and 3.8 GPa, respectively. Carbon nanofiber reinforced syntactic foams show high compressive and tensile properties but they are not yet tested for flexural properties.