Turbulent air flow field in slot-die melt blowing for manufacturing microfibrous nonwoven materials

Abstract

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.

Meltblown technology for production of polymeric microfibers/nanofibers: A review

“…PLEASE CITE THIS ARTICLE AS DOI:10.1063/1.5116336 [14]. Due to heat transfer and mixing with the surrounding air, the air temperature exponentially decreases between die and collector [24], which leads to fiber solidification. Cooling rates are typically in the range 10 3 -10 4 o C/s, as can be deduced from fiber speed and velocity profiles reported in [25,26].…”

“…A model called quasi-one-dimensional model presented by Yarin et al [151] was used for predicting the fiber lay-down patterns on the collector and Battocchio and Sutcliffe [152] also presented a numerical model to describe the fiber dynamics [88]. Xie S. et al discovered connection between the turbulent air flow field and fluctuating velocity and temperature, which contribute significantly to poor evenness of fiber diameters produced by MB process [24]. Chung C. et al [147] observed that annular (rather than 2D) air flows lead to a reduction in fiber distortions and as well as Xie S. et al [153] suggested that melt inertia rather than melt rheology is the more dominant factor in controlling fiber shape.…”

Polypropylene/Polyvinyl Alcohol/Metal-Organic Framework-Based Melt-Blown Electrospun Composite Membranes for Highly Efficient Filtration of PM2.5

“…Melt-blown membranes are the most commonly used in advanced air filters because of its high yield, high strength, and narrow pore size distribution [ 13 ]. Melt-blown fibers with a small diameter are crossed and distributed evenly to obtain a large specific surface area.…”

Particle Image Velocimetry (PIV) Investigation of the Turbulent Airflow in Slot-Die Melt Blowing

“…These two pieces of equipment could measure the airflow with a higher air velocity. Note that the hot-wire anemometer was also used for measuring the melt-blown fluctuating air velocity [14] and the fluctuating air temperature [15]. In addition, the diffusion angle of the airflow in slot-die melt blowing was tentatively measured using a dual-probe hot-wire anemometer, and the results showed that the lateral velocity component was significant for initiating fiber whipping [16].…”