Morphology and mechanical properties of PVA nanofibers spun by free surface electrospinning

Electrospinning has been recognized as a simple and straightforward technique for the production of nanometer and micron-scaled polymer fibers. The technique utilizes electrical forces to stretch and thin fine polymer solution jet drawn from the orifice of a nozzle. Due to the electrical nature of the spinning process, the electrical and ionic conductivity of the polymer solution was proposed to play an important influence on both the process and fiber morphology. This study aims to increase mechanical properties and control nanofiber morphology using a mass production electrospinning technique known as free surface electrospinning. It is found that development of ribbon-shaped fibers was due to thick polymer jets ejected from Taylor cones on the electrode of free surface electrospinning and fast solvent evaporation rate caused by high solution conductivity. Tensile testing of the nanofiber mats indicated higher tensile strength for nanofiber mat spun with solution of enhanced solvent conductivity. Correlating with internal structure characterized in terms of thermally properties and d -spacing, the increased mechanical properties of nanofibers from high conductivity solution were proposed to be attributed to the presence of ribbon-shaped fibers.