Air Velocity, Air Temperature, Fiber Vibration and Fiber Diameter Measurements on a Practical Melt Blowing Die

Abstract

Numerous measurements were taken during the operation of a practical melt blowing slot die. On-line measurements were taken of the mean velocity and temperature of the air jets. Also, on-line measurements of fiber vibration amplitude were done. Off-line measurements were taken to determine fiber diameter distributions in the nonwoven webs. The light absorbance of these nonwoven mats was measured and related to fiber diameter distribution and mat basis weight. Process conditions were varied across the operating range of the die to produce a variety of finished mats. It was found that the mean air velocity and temperature decayed in a manner similar to that observed in both laboratory-scale melt blowing dies and (more generally) in rectangular jets. Fiber vibrations were found to be strongly dependent on operating temperature and air flow rate. The fiber light absorbance correlated well with the projected area of the fibers present in the mat.

Measurement and Comparison of Melt-Blowing Airflow Fields: Nozzle Modifications to Reduce Turbulence and Fibre Whipping

“…There are two ways to investigate the melt-blowing airflow fields: Experimental and computational fluid dynamics (CFD). The experimental work in the literature mainly focuses on the measurement of mean velocity field and mean temperature field [ 14 , 15 , 16 , 17 , 18 ]. In these researches, the mean velocity was obtained through a Pitot tube, while the mean temperature was measured through a thermocouple.…”

Fabrication of nanofiber meltblown membranes and their filtration properties

“…Several studies [16][17][18][19][20][21][22][23][24][25][26] have focused on characterizing the process-structure-property relationships by using techniques such as laser doppler velocimetry and high speed imaging and computational fluid dynamics. Shambaugh et al [20][21][22][23][24][25][26] studied the effect of the slot die geometry on the air flow field below the MB die and its effect on the fiber size. The effect of the nose-piece shape on the flow field under the MB die was investigated experimentally by Tate and Shambaugh [21] and theoretically by using CFD simulations by Krutka and Shambaugh [24][25][26].…”

Air-Filtering Masks for Respiratory Protection from PM2.5 and Pandemic Pathogens

“…However, the unsatisfactory rheological behaviors, especially the low MFI, of many polymers restrict them from forming a uniform web via meltblown. 55 The average fiber diameter produced by commercial meltblown systems is, at best, in the range of 1-10 mm 56,57 ( Figure 5C), and a typical attenuation ratio between the orifice diameter and the final fiber diameter is 100 (from 0.38 mm to 3.8 mm). 57 Six key processing parameters can affect the fiber diameter.…”

“…55 The average fiber diameter produced by commercial meltblown systems is, at best, in the range of 1-10 mm 56,57 ( Figure 5C), and a typical attenuation ratio between the orifice diameter and the final fiber diameter is 100 (from 0.38 mm to 3.8 mm). 57 Six key processing parameters can affect the fiber diameter. (1) Increasing the air velocity decreases the fiber diameter by increasing the aerodynamic drag force; 58 however, a too high air velocity causes fiber breakage.…”