Electrospinning and melt blowing are the most commonly used processes for producing microfibrous nonwoven materials. A whipping motion during electrospinning has been observed by several researchers. However, much less work has been done on the fiber whipping dynamics in the melt blowing process. In this study, a hot-wire anemometer was used to measure the turbulent air flow field below a single-orifice melt-blowing slot die. The characteristics of the mean velocity, mean temperature, and fluctuating velocity were obtained. Then, a high-speed camera was used to record the motion of a fiber below the die. The fiber whipping path was observed, and the amplitude and frequency of the whipping were obtained. It was found that the turbulent fluctuations are related to the fiber motion in the melt-blowing process. This work examines the physics of turbulent melt-blowing jets and the fiber whipping occurring during melt blowing using an experimental approach.

Melt blowing is a major process for producing nanofibrous nonwovens. Compared to studies on the air flow field and the fiber diameter measurement, much less has been done on the observations of whipping in the melt-blowing process. In this study, a high-speed camera was used to capture the fiber path below a single-orifice melt-blowing slot die. The behavior of loops resulted from whipping was revealed. The characteristics of the whipping amplitude, whipping frequency, and fiber velocity were obtained. Fiber attenuation contributed by whipping was calculated by measuring the perimeter of the loops. The study shows the laws of fiber whipping in a slot-die melt-blowing process and indicates that whipping plays a role in fiber attenuation.

Melt blowing is an industrial approach for producing microfibrous nonwoven materials utilizing high-speed air to attenuate polymer melt. The melt-blowing air flow field which is widely believed to be turbulence determines the process of fiber formation. In this study, the turbulent air flow field in slot-die melt blowing was experimental measured by hot-wire anemometer. The fluctuations of air velocity and temperature, the mean velocity and mean temperature were measured and analyzed; moreover, the relationship between turbulent air flow field and fiber formation in melt blowing was discussed and predicted. In the last part of this paper, the coupling effect of air temperature and velocity was studied tentatively, results showed that air temperature not only had an enhanced effect on velocity, but contributed to the fluctuation of velocity. This work shows that the fluctuating characteristics of air velocity and temperature have dominant effect on fiber motion and the evenness of fiber diameter.

Electrospinning and melt blowing are the most commonly used processes for producing microfibrous nonwovens. In this paper, we study mass production of electrospinning with a multineedle system. To achieve uniform fibers at a high production rate, an auxiliary plate electrode has been used to be connected to a three-needle system to obtain a more uniform electric field. The spinnerets with two kinds of needle array, linear three-needle and triangular three-needle, are studied. The results of electrospinning experiments and electric field simulation demonstrate that the multineedle spinneret with an auxiliary plate can produce finer and more uniform nanofibers. And the fibers can be collected in a more concentrated area with the auxiliary plate. We also focus on the effect of the needle length protruded outside the plate. This study shows a possibility that by designing the electric field distribution, we can produce thinner fibers and more concentrated collection mats at a high production rate.

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