The Preparation and Properties of Isotropic Pitch-Based Carbon Felt Prepared by Solvent-Supported Dual Concentric Electrospinning

An isotropic pitch was electrospun in the form of a felt, by adopting a specially-designed dual concentric nozzle system. In the dual nozzle system, the solvent of tetrahydrofuran (THF) flowed independently through the outer nozzle, and relieved the problem of the too rapid coagulation of pitch fibers in the inner nozzle. Unlike the non-woven pitch fabric prepared by conventional electrospinning, the pitch felt had a characteristic morphology of fiber bundles, highly isolated from each other with few fusion points between fibers. The felt morphology was retained, during carbonization of the pitch felt. In consequence, the carbon felt took a sponge-like form, and showed extremely low bulk density of ca. 4.2×10⁻² g/cm³, almost one tenth of that of the polyacrylonitrile-based carbon fibers in the form of non-woven fabric. The cross-section of the felt fibers exhibited the shape of a dog bone, due to asymmetric shrinkage of fibers during electrospinning. Physical properties of the felt were affected by pitch concentration, flow rate, and carbonization temperature. [Figure not available: see fulltext.].