Various experimental techniques and finite element modelling (FEM) were employed to assess mechanical and chemical properties of vinyl-ester (VE)/poly(acrylonitrile-butadiene-styrene) (ABS) blends with different ABS particle content. The blends were to be used as a toughening agent for interlayer toughened VE/glass composite material. Firstly, the materials' fracture toughness and tensile properties were examined, the results showing excellent toughening potential of the blends as well as a non-linear trend for fracture toughness as a function of ABS weight content. The tensile testing of the blends served to define the yield point of the materials and to obtain their stress-strain curves, which were then used as input into finite element analysis models. The mechanical testing results suggested that a chemical reaction may have occurred between the constituents of the blends. Based on the Raman spectroscopy results and mechanical testing data, 7% of ABS was believed to be the critical ABS content where significant changes in the materials' chemical composition and consequently in mechanical properties occurred. Finally, FEM was undertaken to further verify the existence of this sudden variation in material's properties.