Interpretation and use of glints from an electrospinning jet of polymer solutions

Optical observations of jets provide information useful for control of electrospinning of polymer solutions. Combinations of videography, stereography, and methods for illumination of the multiple coils of an electrospinning jet path, that depend on bright glints of reflected light from the jet, recorded quantitative information about the location, vector velocity, and rotation of selected segments of the jet. New bending coils were observed to form at rates of 200–1560 turns per second. This bending frequency decreased as the capillary number of the solutions increased. The polarization of light, in glints reflected at Brewsterʹs angle, allows measurement of the index of refraction of the fluid jet, in flight. Asymmetric illumination of an electrospinning jet made both the handedness and changes in handedness of the electrical bending coils apparent to visual observation and in 2-dimensional images. Evidence was found, in the form of polarized ribbon-like glint traces, for the occurrence of undulations on the surface of some jets.