Evaluation of an onset of electrospun beadless poly(ethylene oxide) nanofibres

Abstract

To evaluate the lowest polymer concentration within a solvent from which there appears beadless nanofibres during the process of electrospinning, is rather complicated. A widely used method is based on a determination of so called entanglement concentration c e and the onsets of beadless nanofibres are characterized by multipliers of c e subjected to used materials. However, a determination of c e as an intersection point of two linear segments (in log-log coordinates specific viscosity vs. concentration) in a semi-dilute region is not applicable for all materials as for instance a solution of poly(ethylene oxide) (PEO) in water does not exhibit 'classical' three linear segments within the dilute and semi-dilute regions determining overlap and entanglement concentrations. For such cases a new approach for the evaluation of an initial concentration from which beadless nanofibres are produced is proposed. This method does not use the terms overlap and entanglement concentrations. The procedure is demonstrated using four PEO solutions differing in molecular weight. The relationship expressing initial concentration in dependence on PEO molecular weight containing no adjustable parameters is proposed.

Fiber Engineering Trifecta of Spinnability, Morphology, and Properties: Centrifugally Spun versus Electrospun Fibers

“…Centrifugally spun emulate properties of electrospun fibers. (a) Diameter, (b) crystallinity, (c) tensile strength, and (d) elongation-at-break of the centrifugally spun fiber mats (data shown in red for this study was produced under matched processing conditions) contrasted with the literature values for electrospun PEO fiber mats produced under varied spinning conditions, and a range of molecular weights and solvent types. ,,− ,− …”

“…With this underlying motivation, we previously tabulated mechanical properties of PEO fibers made using pure AcN and determined that centrifugally spun PEO fibers rival properties of electrospun PEO fibers typically made from aqueous PEO solutions as a spinning dope . In Figure , we contrast the diameter, Young’s modulus, tensile strength, and extension at break for centrifugally spun PEO fibers (this study) with the literature data for electrospun PEO fibers. ,,− ,− By ascribing distinct symbols for data sets extracted from published studies in Figure , we emphasize that only a few measurements exist, and a more systematic study is warranted for connecting properties to macromolecular properties and processing parameters. Here, we utilize Berry number, c [η] (also called overlap parameter), as a combined variable on the x -axis to capture the effect of polymer molecular weight and concentration, as well as solvent quality.…”

Characterization and Filtration Efficiency of Sustainable PLA Fibers Obtained via a Hybrid 3D-Printed/Electrospinning Technique

“…99%, Chempur, Poland). The solution concentration was optimized to obtain beadless fibers [31]. Alternatively, a PLA filament can be used and preferably dissolved in DCM/DMF (4:1) [14]; however, we report only the filtering medium obtained from PLA pellets in acetone due to the use of acetone as a preferable solvent for its availability and low toxicity.…”

An Estimate of the Onset of Beadless Character of Electrospun Nanofibers Using Rheological Characterization

“…For individual materials the multiplicative coefficients k of entanglement concentration ce (where a semidilute entanglement region starts) are determined in such a way that for concentrations lower than k.ce the electrospun nanofibers exhibit singularities (appearance of beads along the nanofibers), and for concentration higher than k.ce the beads are suppressed and the nanofibers exhibit a relatively smooth surface. Most multiplicative coefficients exceed a value of 1 [ 16 ], Table 1 , as e.g., k = 8 for nylon 6 [ 17 ], k = 1.37 for polyimide [ 18 ], but values lower than 1 for some materials are also reported as, e.g., k = 0.8÷1 for poly(ethylene terephthalate) [ 19 ]. A value of the coefficient k varies dependent on the polymer solutions used, and its determination is based on the experiments carried out for a series of concentrations.…”

“…All these properties predetermine PVDF- co -HFP as a very perspective material in membrane production. PVDF- co -HFP membranes are used especially in two spheres: membrane distillation (e.g., in the desalination process, where the membranes gradually replace reverse osmosis) [ 16 ] and in energy storage devices in the form of separators in lithium-ion batteries. Novel trends also find application in biomedicine, e.g., encapsulation of bacteria in core-shell structures [ 20 ] or in endothelialization [ 21 ].…”