Preparation,Structures And Properties Of Epoxy Resin-based Carbon Foams

In order to solve the problems such as difficult molding,high cost and complex manufacturing process and other issues in the preparation of carbon foam,epoxy(EP)resin was modified by bismaleimide(BMI)in the presence of diaminodiphenyl methane(DDM)to prepare a novel carbon foam by performing a series of procedures including casting,curing,and carbonization of the modified resin in this paper.Pyrolysis behaviors of the modified EP resins were investigated using SEM,XRD,FT-IR and TG-DTG.The results show that the modified resin has self-foaming characteristics during pyrolysis process.Its thermal stability increases with the increase of epoxy content.When the mass ratio of DDM,BMI and EP is 1:2:3,its initial decomposition temperature,maximum decomposition rate temperature and the char yield at 1000 ? are 330 ?,376 ? and 24.6%,respectively.In addition,the increase of pyrolysis temperature leads to an improvement in its crystalline structure.The effects of the additive amount of epoxy were investigated on the structures and properties of the carbon foams.The results show that with the increase of epoxy content,the bulk density,thermal conductivity,electrical conductivity and mechanical strength increase,while the pore size,porosity and percentage of open cell decrease.When the mass ratio of DDM,BMI and EP is changed from 1:2:2 to 1:2:4,the thermal conductivity,electrical conductivity,compressive strength and bulk density of the carbon foam increase from 0.258 to 0.348 W/m-K,4.64 to 1.04 S/cm,3.10 to 5.69 MPa,and 0.21 to 0.30 g/cm3,respectively;however,its porosity,percentage of open cell decrease from 87.2%to 82.7%and 71.2%to 60.7%,respectively.The effects of the additive amount of mesophase pitch were investigated on the structures and properties of the resulting carbon foams.The results show that with the additive amount of mesophase pitch from 2.5%to 10%,its bulk density decreases,but the porosity and percentage of open cell increases.Meanwhile the cells are deformed and the cracks appear.When the additive amount varies from 2.5%to 10%,its bulk density, thermal conductivity,and compressive strength decrease from 0.30 to 0.21 g/cm3,0.426 to 0.357 W/m-K and 4.51 to 3.92 MPa,respectively;however,its porosity,percentage of open cell,electrical conductivity increase from 67.2%to 75.1%,87.0%to 90.1%,20.35 to 37.25 S/cm,respectively.In addition,the degrees of graphitization increases and the foam structure becomes more orderly.The effects of high-temperature treatment were investigated on the structures and properties of the resulting carbon foams.The results show that the microcrystalline structure of the carbon foam is improved with the increase of treatment temperature,and meanwhile its graphitization degree increases.When the heat treatment temperature varies from 1200 ? to 1800 ?,the compressive strength and electrical conductivity of the carbon foam increase from 22.32 to 43.37 S/cm and 3.59 to 6.01 MPa,respectively.