Processing-Mechanical Property Relationship of Hollow and Porous Carbon Fibers Fabricated by Coaxial Electrospinning

High strength hollow carbon fibers with both porous and solid shell were fabricated by a combination of coaxial electrospinning and emulsion electrospinning. In the coaxial electrospinning, a Polyacrylonitrile (PAN)/ Poly(methyl methacrylate) (PMMA)/Dimethylformamide (DMF) emulsion was used to form the porous shell and a PAN/DMF solution was used to form the solid shell. Fiber surface and cross-section morphology was studied by scanning electron microscope (SEM). Mechanical property of the hollow fibers was characterized by single fiber tensile test using microelectromechanical system devices (MEMS). The effect of pores on mechanical performance of the hollow fibers was studied. Hollow carbon fibers with porous and solid shell both showed a brittle fracture behavior. The modulus and strength of the hollow carbon fibers with solid shell was ∼ 76.1 GPa and 2.04 GPa, respectively. For the hollow carbon fibers with porous shell, the porosity led to ∼ 35 % reduction in strength. The porous fibers with the mediocre strength measured here open new horizons for combining structural functionality with energy storage, in so-called structural batteries.