Effect of H3BO3 modification on the char yield of epoxy resin and structure and property of epoxy resin carbon foam

H 3 BO 3 promotes the removing oxygen-containing functional groups of epoxy resin (EP) and forms B-O-C bond with EP during pyrolysis. Char yield of EP is decided by the chemical crosslinking of EP and H 3 BO 3 and H 3 BO 3 dehydration. The char yield of 0 and 9 wt% H 3 BO 3 modified EP are 19 and 33.4 wt%, respectively. The graphitization degree and grain stacking thickness of EP carbon foam (CF) first decrease and then increase with H 3 BO 3 increase. The graphitization degree of 0, 3, 6, 9 and 12 wt% H 3 BO 3 modified EP CF are 0, 11.6, 0, 0, and 23.2 %, respectively. Furthermore, the I D /I G value of 0, 3, 6, 9, 12 wt% H 3 BO 3 modified EP CF are 0.97, 1.05, 1, 1.1, and 0.89, respectively. For 0 and 3 wt% H 3 BO 3 , the bubbles combine easily and form bigger cell size of CF. When the H 3 BO 3 is 6 wt% above, the combination of bubbles become difficult, and decreases cell size of CF. However, the cell size (760 μm) of 12 wt% H 3 BO 3 modified EP CF is the maxim due to H 2 O foaming. The electrical conductivity of 0 and 3 wt% H 3 BO 3 modified EP CF is 15.56 to 25.94 S/m, respectively, which is decided by the CF carbon graphite structure and its density. The compressive strength of H 3 BO 3 modified EP CF gradually decreases with H 3 BO 3 increase, which is influenced by CF density. The compressive strength (0.6 Mpa) of 12 wt% H 3 BO 3 modified EP CF is much lower than pure EP CF (3.32 MPa).