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

Abstract

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 106 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.

Study on the foaming behavior of density‐controllable epoxy resin composite foam under negative pressure environment

“…[4][5][6] At present, the preparation methods of thermosetting ERCF are mainly focused on the chemical foaming method, physical foaming way, and hollow microspherefilled foaming strategy. [7][8][9][10][11] For example, Ma et al 12 prepared a new composite foaming agent by filling the cells of microporous silica with the chemical foaming agent 4,4 0oxobenzenesulfonyl hydrazide (OBSH), which can be used as both filler and foaming agent, and the ERCF can be easily produced by the decomposition of the foaming agent. The advantage of this method is that good-performance foam can be produced by simple process operations, 13,14 but the disadvantage is obvious, for example, lots of organic chemical foaming agents or their by-products are toxic, and the incomplete decomposition of foaming agent as well as its decomposition residues make negative effect on mechanical properties of the material, so the use of chemical foaming agent has become one of the main problems affecting the performance of ERCF.…”