Fabrication and characterization of two-phase syntactic foam using vacuum assisted mould filling technique

Conventional mould casting technique for cell foam production demonstrated trapped air bubbles in the cell foam which are undesirable stress concentration points in the matrix. This study devise a modified process technique of fabricating syntactic foam by eliminating interstitial porosity. Varying epoxy hollow spheres and matrix stoichiometry ratio was involved in the fabrication of syntactic foam. Analysis through characterization of the mechanical properties, macrostructural morphology, cell size distribution, wall thickness and curing conditions was determined. The influence of fabrication techniques on performance of the syntactic foams was also evaluated. From the results the hollow sphere size distribution prevented the interstitial spaces, enhanced density and create foam compactness. The matrix stoichiometry ratios impacts the foam morphology, the optimal formulation was 1:1 because it enhances cross-linking within the matrix and produced a smooth, strong surface microsphere coating with structural rigidity. The relative density, compressive modulus and compressive strength of the syntactic foam are 377.11 kg/m3, 556.39 MPa, 10.40 MPa and 334.61 kg/m3, 37.05 MPa, 4.11 MPa, for vacuum assisted mould filling and conventional mould casting method, respectively. Crack propagation test showed failure started at the center and spread through the edges of the syntactic foam because of good interfacial bonding between sphere and matrixes.