Short-Beam Three-Point Bend Tests in Syntactic Foams. Part II: Effect of Microballoons Content on Shear Strength

Epoxy binders containing microballoons ranging from 38.5 to 57.7% by volume were cast in a mold and cured, and the resulting slabs were sectioned to yield short-beam test coupons. The strength changes with microballoons content were noted. These reveal an increase from 3.87 to 5.79 MPa for a decrease in microballoons content from 57.7 to 38.5%. Mechanical data were correlated with fractographic features employing scanning electron microscope. The failure features involving the microballoons and interface regions are highlighted in this article. The works show the existence of a dependence of strength parameters on the inter-microballoon distances. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 680–686, 2005