Study Of Carbon Foams From Epoxy-modified Bismaleimide Resin

In order to solve the problems existing in the preparation of carbon foam such as complex technology,high cost,low percentage of open cell,poor mechanical strength and other issues,epoxy(EP)-modified bismaleimide(BMI)resins were used to prepare carbon foams by a range of synthesis process involved casting,curing,and carbonization in this paper.The structure changes of the epoxy-modified bismaleimide resins during heat treatment process were investigated.Furthermore,structures and properties of the carbon foams were studied.Structures and pyrolysis behaviors of epoxy-modified bismaleimide resins were studied by SEM,FT-IR,TG-DTG and XRD.Results show that the copolymer resin has self-foaming characteristics in pyrolysis process.The thermal stability of the resin increases with the increase of epoxy content.When the mass ratio of diallyl bisphenol A(DABPA),BMI and EP is 2:3.6:2,the resin obtained has an initial decomposition temperature of 311 ?,a maximum decomposition rate temperature of 428 ? and the char yield is 26.83%after carbonization at 1000 0C.Furthermore,the crystalline structure is improved with increasing pyrolysis temperature.The effects of the additive amount of epoxy on the structures and properties of the carbon foams from epoxy-modified bismaleimide resin were studied.Results show that with the increase of epoxy content,the bulk density,thermal conductivity,mechanical strength and electrical conductivity increase at the same time,whereas the pore size,porosity and percentage of open cell decrease.When the mass ratios of DABPA,BMI and EP varies from 2:3.6:0 to 2:3.6:6,the thermal conductivity,compressive strength,electrical conductivity and bulk density of the carbon foam increase from 0.287 to 0.419 W/m K,0.98 to 4.01 MPa,3.58 to 12.7 S/cm and 0.22 to 0.32 g/cm3,respectively,but its porosity,percentage of open cell and char yield decrease from 85.35%to 79.96%,77.89%to 51.23%and 33.88%to 23.50%,respectively.The effects of high temperature processing on the structures and properties of carbon foams from epoxy-modified bismaleimide resin were studied by tuning heat treatment temperature.The results show that with the increase of heat treatment temperature,the degree of graphitization of resultant carbon foam is improved.When the heat treatment temperature increase from 1200 ? to 1800?.the electrical conductivity and compressive strength of the carbon foam,prepared with the mass ratio of 2:3.6:6,increase from 24.18 to 64.10 S/cm and 1.32 to 5.65 MPa.