Core effect on mechanical properties of one dimensional electrospun core-sheath composite fibers

Mechanical properties are highly important for the applications of electrospun nanofibers. In this work, the core effect on mechanical properties of one dimensional electrospun core-sheath composites was investigated. Coaxial electrospinning was used to prepare polyacrylonitrile (PAN)/thermoplastic polyurethane (TPU) core/shell composite fibers with different core diameters of PAN by controlling the flow rate of core solution. Theoretical calculation and electron microscopy were used to determine the core diameter. Micro tensile tests were applied to characterize the mechanical properties of single pure PAN, pure TPU and PAN/TPU core/shell composite fibers. The results indicated that the theoretically calculated core diameter had a good agreement with the electron microscopy measurement. The tensile tests indicated that as the core diameter increased, the elongation decreased while modulus increased. The tensile strength and toughness exhibited a complicated trend, where the increase and decrease were observed alternately. The strategy of adjusting the core diameter to modify the mechanical properties core/shell composite electrospun fibers could be applied to other core/shell material systems.