Synthesis Of Carbon Foam And Control Of Their Structure

Carbon foams are a new class of lightweight porous carbon materials which consist of an interconnected ligament network. Because of their high open-cell ratio, low bulk density and large specific surface area, carbon foams are being developed for use as thermal management materials, electrode materials, supercapacitor, catalyst supports and so on.This thesis synthesized carbon foam at ambient pressure. The research used phenolic resin which is obtained by letting a resinous mixture comprising m-phenol diamine, formaldehyde as precursor, and then dispersing blowing agent in it with agitating or ultrasonic oscillations, via physical blowing technique and non-supercritical drying technique, we obtained phenolic resin foams. The resin foams were carbonized under argon atmosphere at 1000℃, and then slowly cooling down to room temperature to produce carbon foams. Their structural features were characterized by SEM, BET and XRD technique. The carbon foams obtained by this method are lightweight solid carbon materials which are made of carbon frameworks with ligaments and junctions, the average diameters of cell sizes are from 50μm to 300μm, the apparent density is about 0.32 g/cm~3, while the surface areas ranging from 500 to 600m~2/g with very high open cell radio. After graphitized at 2000℃, the simple will change from amorphous carbon foam to Graphitic carbon foam. Various structural carbon foams with the apparent open cell diameters of 150-250μm can be synthesized by controlling the viscosity of phenolic resin prepolymer, proportion of blowing agent and the foaming condition(i.e. blowing temperature, blowing volume).On addition, another kind of carbon foams which have the different structure have been synthesized via emulsion polymerizations. And their structure is related with the kind of solidifying agent. With sodium hydroxide as solidifying agent, the carbon foams will have obvious pores; with ammonia water as solidifying agent, the structure of foam is the faviform, which is made up of uniform carbon sphere with diameters of about 1μm. Carbon foam's structure is also affected by forming...