No abstract

This study provides a thorough description associated with multijet motion and deviation in electrospinning.

Co-electrospinning is a new branch of nanotechnology for producing composite nanofibers with collective functions and special fiber structures. Helical fibers in nanoscale have been of increasing interest because of their unique characteristics. In this work, we report the fabrication of the helical nanofibers with polyurethane and poly­(m-phenylene isophthalamide) by the co-electrospinning system with an off-centered core–shell spinneret. High-speed photography and three-dimensional (3D) electric field simulation are carried out to help in understanding the formation of the helical structures. The asymmetrical electric field distribution may be a factor affecting helical fiber formation. We also show that a series of factors such as the applied voltage, the conductivity of the system, and the composite ratio have considerable effects on the morphologies of the produced helical nanofibers. This work can provide a promising technique for producing nanofibrous nonwovens with helical fiber morphology.

This study presents a multihole spinneret with a metal flat electrode to obtain uniform electric field and meet a high production requirement. We demonstrate that the multihole spinneret produces finer fiber diameters and more concentrated fiber mat compared to the conventional multineedle electrospinnig system. This study focuses on the effect of the electric field distribution on the spinning process and the resultant nanofibers. The three-dimensional electric field simulation results show that the multihole spinneret creates not only a more uniform electric field, but also a stronger electric field except for the area very close to the spinneret. The measurement of the electric field verifies the simulation results. This study shows that fine fibers, as well as concentrated and thick fiber mat can be obtained by this multihole electrospinning system at a high production rate.

Melt blowing is a technology for producing microfibrous nonwovens. The melt-blowing die is the key component of the melt-blowing device. In this study, a slot die and a swirl die were used to study the effects of die geometry on fiber motion and fiber attenuation in the melt-blowing process. The fiber paths in these two melt-blowing processes were recorded dynamically with a high-speed camera at a shutter speed of 3000 frames per second. The fiber path profiles, especially the whipping behavior, were for the first time obtained and presented. The recorded images were further processed to interpret the law of fiber motion and to determine the fiber velocity. A mathematical method was also constructed to qualify the fiber diameters instantly below the two dies, which are undetectable upon experimental measurement. The results show that fiber whipping in the slot-die melt-blowing process is a two-dimensional motion. In contrast, it appears as a spiral path in three dimensions in the swirl-die melt-blowing process. The swirl die creates more rapid fiber attenuation in the region near the die.