3D long fiber-reinforced syntactic foam based on hollow polymeric microspheres

Composite syntactic foams comprised of amino microspheres reinforced with chopped fibers were fabricated using a phenolic resin binder. Compressive, shear, and tensile strength and moduli were measured in directions parallel and perpendicular to the preferred fiber orientation. The results showed substantial increases in strength and modulus compared with the unreinforced (neat) foam when measured parallel to the preferred fiber orientation. When loaded perpendicular to the dominant fiber orientation, properties were enhanced 30–40%, but when load was applied parallel to the dominant fiber orientation, the compression strength of the composite foam increased by a factor of up to 2; the tensile strength and modulus increased by a factor of up to 7 and 8, respectively, and the shear strength and modulus increased by a factor of up to 3.3 and 2.3, respectively. The fibers were more effective in enhancing the strength of syntactic foams when loads were applied parallel to the dominant fiber orientation.