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Electrospinning of several polyamides, PA6, PA66, PA612, PA614, PA1012, and PA1014, having different chain compositions and lengths of diacid and diamine segments, was demonstrated. Electrospinnability and fiber production rate of these polyamides were evaluated. Electrospun fibers were characterized with regard to their use in air filtration by measuring fiber diameter and filtration efficiency of fiber coating. Longer nonpolar chain segments of higher polyamides could in theory indicate higher dielectricity compared to PA6 and PA66, which would be an advantage in filtration applications. The solubility in polar formic acid and electrospinnability of higher polyamides, on the other hand, were clearly impaired with increased length of chain segments. Hence, PA66 is our best choice, and PA612 and PA6 our second options for commercial filtration applications if fiber electrospinnability, production rate, fiber diameter, and its distribution are concerned. Filtration efficiency of more than 95% of the particles having a diameter of 0.16 lm and above was achieved with 0.5 g/m 2 coating of PA66 nanofibers. Further increase in coating weight mainly increased the pressure drop to an unusable range without a significant further improvement of filtration efficiency.Like reviewed earlier some simple polyamides, such as PA6 and PA12, and some copolyamides such as PA66 and PA46 are verifiably applicable in electrospinning. Still, we can suppose that the structure of the polyamide FIG. 2. Electrospun PA66 fibers produced from solution having concentrations of (a) 6%, (b) 9%, (c) 12%, and (d) 15%. FIG. 4. Fiber diameters with standard deviation and fiber production rates of different polyamides. FIG. 5. X-ray diffraction spectrums of (a) newly electrospun PA6 sample and (b) after 2 months ageing.

In this study an optical cellulose fiber for water sensoring was prepared by using a sequential preparation strategy. The core of the fiber was prepared from dissolved cellulose, in [EMIM]OAc, which was dry–wet spun into water. The cladding layer on the cellulose core was produced by coating a layer of cellulose acetate, dissolved in acetone, using a filament coater. The chemical and optical properties of both regenerated cellulose and cellulose acetate were studied from cast films using ultraviolet–visible and Fourier-transform infrared spectroscopy measurements. Regenerated cellulose film was observed to absorb UV light, passing the visible light wavelengths. Cellulose acetate film was observed to pass the whole light wavelength range. The mechanical strength and topography of the prepared optical cellulose fiber were investigated through tensile testing and SEM imaging. The mechanical performance of the fiber was similar to previously reported values in the literature (tensile strength of 120 MPa). The prepared optical fiber guided light in the range of 500–1400 nm. The attenuation constant of the cellulose fiber was observed to be 6.3 dB/cm at 1300 nm. The use of prepared optical cellulose fiber in a water sensor application was demonstrated. When the fiber was placed in water, a clear attenuation in the light intensity was observed. The studied optical fiber could be used in sensor applications, in which easy modifiability and high thermal resistance are beneficial characteristics. Graphic abstract Coaxial cellulose acetate-regenerated cellulose fiber for transporting light in sensor optical fiber sensor applications.

Towards internal structuring of electrospun fibers by hierarchical self-assembly of polymeric comb-shaped supramolecules Ruotsalainen, T; Turku, J; Heikkila, P; Ruokolainen, J; Nykanen, A; Laitinen, T; Torkkeli, M; Serimaa, R; ten Brinke, G; Harlin, A Link to publication in University of Groningen/UMCG research database Citation for published version (APA): Ruotsalainen, T., Turku, J., Heikkila, P., Ruokolainen, J., Nykanen, A., Laitinen, T., ... Nykänen, A. (2005). Towards internal structuring of electrospun fibers by hierarchical self-assembly of polymeric comb-shaped supramolecules. Advanced materials, 17(8), 1048-+. https://doi