Abstract
In melt blowing, microfibrous nonwoven material is manufactured by using high-speed air to attenuate polymer melt. The melt-blown air jet determines the process of polymer attenuation and fiber formation. In this work, the importance of lateral velocity on the fiber was first theoretical verified. The lateral diffused characteristic of the air flow field in slot-die melt blowing was researched by measuring the velocity direction using a dual-wire probe hot-wire anemometer. Meanwhile, the fiber path was captured by high-speed photography. Results showed that there existed a critical boundary of the lateral diffusion, however, air jets in the x–z plane are a completely diffused field. This work indicates that the lateral velocity in the y–z plane is one of the crucial factors for initiating fiber whipping and fiber distribution.
Highlights
Melt blowing is an industrial approach for manufacturing nonwoven materials
During the melt blowing process, the raw material of solid particles is melted by the effects of heating and the screw’s shear stress, and subsequently extruded out through the orifice, the microfibers are formed by attenuating the melt with high-velocity hot air
More-advanced measuring equipment like laser Doppler velocimeters and hot-wire anemometers with one-dimensional probes were applied for measuring the melt-blown air flow fields [7,8,9,10,11], the maximum air velocity they measured increased to be about 150 m/s
Summary
Melt blowing is an industrial approach for manufacturing nonwoven materials. Melt-blown nonwoven materials have found a variety of advanced applications in areas of filtration, life science, medicine, and industry [1,2], the fiber diameter is commonly in the range from about 1 μm to several micrometers.During the melt blowing process, the raw material of solid particles is melted by the effects of heating and the screw’s shear stress, and subsequently extruded out through the orifice, the microfibers are formed by attenuating the melt with high-velocity hot air (see Figure 1). By means of the high-frequency signal acquisition principle of the hot-wire anemometer, Xie [11] measured the fluctuation of turbulence in melt blowing and discussed the relationship between turbulence and fiber motion. It noted that, air velocity is a vector and has the characteristics of directivity, these previous experimental measurements provided the velocity along the spinning line, the directional information of velocity was unavailable, especially for positions not along the spinning line, generally, these measured velocities were considered to have a direction parallel to the spinning line. The air flow field was researched with a lack of information along the lateral direction
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