Advanced Materials Research Vol. 843

Abstract: Poly (vinyl alcohol) (PVA), a classical biodegradable polymer, is successfully fabricated into nanofibers via the vibration-electrospinning, and the obtained nanofibers are characterized by the scanning electron microscopy (SEM). The viscosity and electrical conductivity of PVA solution vary dramatically with the ultrasonic radiation time and intensity. The novel strategy can produce finer nanofibers than those obtained without ultrasonic vibration.

Abstract: Weakness of electrospun nanofiber has impeded its industrial applications for a long period. Our studies reveal a promising solution to this problem by applying ultrasonic vibration to the polymer solutions during electrospinning. To well understand and control of this new technology, a mathematical model is much needed. During the vibration, heat and vibration induced by the ultrasonic energy will not only affect the rheological properties of the polymer solution and the energy balance of the electrospinning system, but play an important role on the current generated in the charged jet. Taking consideration of such impacts of ultrasonic vibration, governing equations for current, momentum and energy are derived, and a simplified model is also provided for practical applications.

Abstract: Polyvinyl alcohol (PVA) with a degree of 1750±50 was successfully fabricated into nanofibers via the traditional electrospinning process. Daughter charged jets and combined fibers were observed. A combined fiber might be simple combination of two separate fibers without mass transfer, or it is a daughter cascade caused in hierarchical motion of a charged jet with mass/energy transfer. Minimal fiber reaches as small as 5nm (50 angstroms) in diameter, this might be the smallest artificial fiber, which might have excellent properties due to nanoeffect.

Abstract: Nanofibers with high orientation are of significant applications. This paper demonstrates a method to fabricate high orientation ordered nanofibers by electrospinning. The distribution of the electric field is simulated by using computational fluid dynamics software ANSYS14.0 to illustrate its mechanism.

Abstract: Multi-bubble electrospinning is considered as one of efficient techniques which have potential for large scale production of nanofibers. However, there is a lack of published research to better understand the formation of bubbles and the mutual interference among these bubbles. In this paper, the formation methods of multiple bubbles on the free liquid surface were examined to determine which ones performed relatively well. The influence of solution concentration, applied voltage, gas pressure, liquid length and the shape of electrode on the process and morphology of nanofibers were also investigated. The results showed that multiple gas tubes in the solution was the best choice to produce stable multiple bubbles though the number of bubbles was less than that obtained by the other methods. Some important processing parameters, such as solution concentration, applied voltage and the shape of electrode, had an important influence on the morphologies of nanofibers. Finally, both experimental and theoretical investigations in this process proved that the mutual interference among bubbles existed during multi-bubble electrospinning process.

Abstract: Two dimensional NanoNet is obtained by the bubble electrospinning, its mechanism is elucidated and experimental verification is given. Combined fibers in the NanoNet might be simple combination of two separate fibers, or it is a daughter cascade caused in hierarchical motion of a charged jet. A criterion is given to identify simple combination and daughter cascades by using area conservation, mass conservation and moment conservation. Experiment verification of these criterions is given.

Abstract: Bubble-electrospinning is one of the most straightforward ways to fabricate polymer solution into nanofibers. The key point of the technology is to control bubble size and formation frequency. A modified bubble electrospinning set-up is designed to control the size of polymer bubbles and frequency of bubble formation in the spinning process. A PVA (10wg %) solution is used in the experiment for fabricate polymer solution into nanofibers and superfine nanofibers are obtained with the average diameter of about 200nm.

Abstract: The electrospinning is used to produce environment-friendly and degradable nanoparticles. The edible starch is used as the electrospinning solution and water as solvent, and size of the nanoparticles is controllable by the solution concentration.

Abstract: During electrospinning process, charged web jets solidify with solvent evaporation and form two-dimensional (2D) web-like nanofibers on the collecting plate. In this paper, Poly [(lactic acid)-co-(glycolic acid)] (PLGA) solutions are used to produce different 2D web-like nanofibers, which can mimic the physical features of natural extracellular matrix (ECM) at the nanoscale and improve fibroblast growth. According to mass conservation, the possible mechanisms for the web formation are investigated.