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.
Highlights
Melt blowing is one of industrial approaches for manufacturing nonwoven materials
Because of the fiber diameter produced by melt blowing is commonly in the range from about 1 lm to several micrometers, the melt-blown nonwoven materials have found a variety of advanced applications in areas of filtration, life science, medicine and industry [1, 2]
The air flow field plays a crucial role in fiber formation during melt blowing
Summary
Melt blowing is one of industrial approaches for manufacturing nonwoven materials. Because of the fiber diameter produced by melt blowing is commonly in the range from about 1 lm to several micrometers, the melt-blown nonwoven materials have found a variety of advanced applications in areas of filtration, life science, medicine and industry [1, 2].During melt-blowing process, the microfibers are manufactured by extruding a polymer melt through an orifice (a component of die), and attenuating the extrudate with a jet of high velocity hot air (seeFig. 1). The air flow fields in melt blowing have been researched mostly by methods of computational fluid dynamics (CFD) numerical simulation and experimental measurement. Shambaugh and his co-workers [3,4,5,6,7] have systematically numerical simulated the air flow fields in different kinds of die melt blowing, including slot die, annular die and swirl die. More advanced equipments with higher accuracy, such as hot-wire anemometer and laser Doppler velocimeter were applied to measuring the air flow fields [13,14,15,16], the maximum velocity they measured increased to be about 150 m s-1. It noted that the air flow fields all they have measured were described by average values, namely, the turbulent characteristic of air flow field was not provided
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