Co-continuous hollow glass microspheres/epoxy resin syntactic foam prepared by vacuum resin transfer molding

It is generally accepted that matrix pores in the hollow glass microspheres (HGMs)/resin-based composites prepared using stir-casting method (SCM) seriously affect its performance. In this paper, HGMs preforms were prepared using sintering method, and co-continuous HGMs/epoxy resin syntactic foams were prepared using vacuum resin transfer molding (VARTM) method. In order to compare how preparation method affects properties of the composites, the same volume fraction of HGMs filled epoxy resin composites was prepared by SCM. The effects of preparation methods on microstructure, density, compression properties and water absorption of composites were investigated. Compression deformation mechanism of the composites prepared by two methods is discussed. Syntactic foam with the same HGMs volume fraction contained different porosity depending on the preparation method. Porosity of the matrix in the composite prepared using SCM was similar to 10 vol.%, while the densities of composites prepared by VARTM were close to the theoretical density, indicating no matrix pores. Co-continuous HGMs/epoxy resin syntactic foams prepared using VARTM showed properties superior to syntactic foams prepared by SCM: compressive strength increase by 45.31%, compressive modulus increase by 37.63%, and water absorption decrease by 69.91%. All these properties improved mainly because of the elimination of the matrix pores.