Preparation of carbon foams by thermo-foaming of activated carbon powder dispersions in an aqueous sucrose resin

Abstract

Thermo-foaming of activated carbon (AC) powder dispersions in an aqueous sucrose resin followed by carbonization has been studied to prepare carbon foams. The dispersions were characterized by viscosity measurements and sedimentation studies. The OH to OH condensation reactions, leading to the cross-linking of the sucrose polymer, were retarded by the AC powder. The AC particles adsorbed on the gas–liquid interface stabilized the gas bubbles that resulted in foaming of the poorly cross-linked sucrose polymer resin having low viscosity. The carbon produced by the carbonization of the sucrose polymer binds the AC particles as in reaction bonding. The carbon foams have an interconnected cellular structure. Density (0.138–0.22g/cc), cell size (0.62–3mm) and compressive strength (0.42–3.4MPa) of the carbon foams depends on the AC powder to sucrose weight ratio. Incorporation of the AC powder in the sucrose resin decreases the carbonization shrinkage that enables the preparation of large carbon foam bodies without warping. The carbon foam prepared at an AC powder to sucrose weight ratio of 0.1 shows the highest density and compressive strength and the lowest cell size.