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

H 3 BO 3 promotes the removing oxygen-containing functional groups of epoxy resin (EP) and forms B-O-C bond with EP. The char yield of EP increases first and then decreases with H 3 BO 3 content increasing, which is 33.4 wt% and 19 wt% for 9 wt% H 3 BO 3 modified EP and EP. The graphitization degree ( g ) and grain stacking thickness ( L c ) of EP carbon foam (CF) first decrease and then increase with H 3 BO 3 increase. The graphitization degree ( g ) of 3, 6, 9 and 12 wt% H 3 BO 3 modified EP CF are 11.6, 0, 0, and 23.2%. 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. For low H 3 BO 3 content (0, 3 wt%), the small bubbles combined easily, and led to bigger bubble size. When the H 3 BO 3 content was high (above 6 wt%), the combination of small bubbles becomes more difficult, and decreases cell size. The cell sizes of 0, 6, 12 wt% H 3 BO 3 modified EP CF are 620 µm, 440 µm, 760 µm, respectively. When the H 3 BO 3 varies from 0 and 3 wt%, the electrical conductivity of modified EP CF increased from 15.56 to 25.94 S/m. The compressive strength of the H 3 BO 3 modified EP CF gradually decreased with increase of H 3 BO 3 from 0 to 12 wt%, which can be influenced by its density. The compressive strength of 12 wt% H 3 BO 3 modified EP CF is only 0.6 Mpa, which is much lower than the EP CF (3.32 MPa).