Preparation of epoxy resin foam by composite foaming agent prepared from microporous silica and 4,4′-bisoxybenzenesulfonyl hydrazide

Generally, foamed epoxy resin prepared by chemical method has relatively large average cell size and low cell density, resulting in low mechanical properties and poor heat resistance. In this work, a new type of composite foaming agent (CFA) was prepared by filling the chemical foaming agent 4,4′-bisoxybenzenesulfonyl hydrazide (OBSH) into microporous silica microspheres (MSMs), and then used for epoxy resin foaming research. The effects of curing agent diethylenetriamine (DETA) and CFA contents on cell density and size were also discussed. The best epoxy resin foaming sample has a cell density of 10 6 cells cm −3 with an average cell diameter of 65 μm, and a high compressive strength of 34 MPa as well as a good heat resistance. These results indicate the potential application of CFA in epoxy resin foaming area.