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Solution blowing is one of the most industrially viable processes for mass production of nanofibers without significant change of trade practices. In this work a novel industrially scalable approach to nanofiber production by solution blowing is demonstrated using Biax die. Blends of biopolymer soy protein isolate Clarisoy 100 and poly­(ethylene oxide) (M w = 600 kDa) were solution blown as aqueous solutions using a spinneret with 8 rows with 41 concentric annular nozzles. Nanofiber mats were collected on a drum, and samples with an area of the order of 0.1–1 m2 were formed in about 10 s. Nanofibers were relatively uniform with the diameters of about 500–600 nm. Theoretical aspects of capillary instability, dripping, and fly formation in solution blowing relevant from the experimental point of view are discussed, as well as ways of their prevention are revealed.

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In this study, we investigated the effect of polymer type, composition, and interface on the structural and mechanical properties of core-sheath type bicomponent nonwoven fibers. These fibers were produced using poly(ethylene terephthalate)/polyethylene (PET/PE), polyamide 6/polyethylene (PA6/PE), polyamide 6/polypropylene (PA6/PP), polypropylene/polyethylene (PP/PE) polymer configurations at varying compositions. The crystallinity, crystalline structure, and thermal behavior of each component in bicomponent fibers were studied and compared with their homocomponent counterparts. We found that the fiber structure of the core component was enhanced in PET/PE, PA6/PE, and PA6/PP whereas that of the sheath component was degraded in all polymer combinations compared to corresponding single component fibers. The degrees of these changes were also shown to be composition dependent. These results were attributed to the mutual interaction between two components and its effect on the thermal and stress histories experienced by polymers during bicomponent fiber spinning. For the interface study, the polymer-polymer compatibility and the interfacial adhesion for the laminates of corresponding polymeric films were determined. It was shown that PP/PE was the most compatible polymer pairing with the highest interfacial adhesion value. On the other hand, PET/PE was found to be the most incompatible polymer pairings followed by PA6/PP and PA6/PE. Accordingly, the tensile strength values of the bicomponent fibers deviated from the theoretically estimated values depending on core-sheath compatibility. Thus, while PP/PE yielded a higher tensile strength value than estimated, other polymer combinations showed lower values in accordance with their degree of incompatibility and interfacial adhesion. These results unveiled the direct relation between interface and tensile response of the bicomponent fiber.

Assuming that fibers can be represented as straight cylinders, an algorithm for generating virtual 3D layered fibrous media made up of fibers having identical diameters but different lengths is presented. It is shown that for a given basis weight and computational box (sample size), reducing the fiber length causes the solid volume fraction (SVF) to increase as the fibers pack next to one another more efficiently. The air permeability of these media is numerically simulated and discussed in detail with respect to the available 2D and 3D studies in the literature. Our permeability calculations show an excellent agreement with the predictions of the empirical equation of Davies [1] as well as the analytical model of Spielman and Goren [2]. Such an agreement indicates that, within the range of dimensions considered, the fiber length has no significant influence on the materials' through-plane permeability as long as the SVF remains constant. While this concept has been empirically observed in the past, our work is the first numerical simulation devised to confirm it.

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