Shear flow of molten polymer in melt blowing

Abstract

Besides the air flow field, the flow field of molten polymer plays a key role in fiber formation in the melt‐blowing (MB) process. In this article, the flow field of molten polymer was discussed, and its effects on the fiber microstructures were studied through theory and experiments. First, this field was supposed to be a kind of shear flow field. Two equations were introduced and solved. Then, analyzing the solutions combining with the actual melt‐blown practice, we concluded that the distribution profile of this flow field was a series of inverse parabolic in the course of the polymer stream attenuating. Further inferring from this flow pattern, we could also assume that there could have been a novel cross‐sectional microstructures in the melt‐blown fibers. Finally, the comparison experiments concerning the MB and its fibers were designed and carried out. The results indicated that the shear flow field could be qualitatively described by the equations, and the assumptions about the microstructures are basically in agreement with the experimental results. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers

Physical and thermal characterization of polylactic acid meltblown nonwovens

“…The presence of the peak at 155°C is attributed to crystal transition from a less ordered β form having 3 1 helical conformation to more ordered α form with a 10 3 helical conformation. The presence of the less organized crystal structure in the interior of the fiber can be explained as polymer flow during the processing resulting in radial distribution of crystal perfection . This is reflected in increases of the onset of cold crystallization for microfibers.…”

“…This is reflected in increases of the onset of cold crystallization for microfibers. The polymer flow through the die can effect the internal microstructure of the fiber . Differences in the interior fiber microstructure are more prevalent for the larger microfibers than for the nanofibers.…”

“…The presence of the less organized crystal structure in the interior of the fiber can be explained as polymer flow during the processing resulting in radial distribution of crystal perfection. 20 This is reflected in increases of the onset of cold crystallization for microfibers. The polymer flow through the die can effect the internal microstructure of the fiber.…”

“…The polymer flow through the die can effect the internal microstructure of the fiber. 20 Differences in the interior fiber microstructure are more prevalent for the larger microfibers than for the nanofibers. This is indicated by a higher presence by of b crystals from the DSC thermograms in Figure 6 and quantified in Figure 7.…”

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

“…Visualization of fiber attenuation in post die area during MB process (left) together with particular velocity profiles in cross sections A and B (right) [16][17]. This is the author's peer reviewed, accepted manuscript.…”