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Needleless Electrospun Nanofibers for Drug Delivery Systems
Published in K.M. Praveen, Rony Thomas Murickan, Jobin Joy, Hanna J. Maria, Jozef T. Haponiuk, Sabu Thomas, Electrospun Nanofibers from Bioresources for High-Performance Applications, 2023
Jolius Gimbun, Ramprasath Ramakrishnan, Praveen Ramakrishnan, Balu Ranganathan
A rotating roller attached to a high applied voltage supply produces nanofibers. Cylindrical geometry facilitates free flow and circumvents fluid flow resistance, hence making the roller a good choice. The rolling unit served a dual purpose, both as a polymer solution reservoir and a nanofiber generator. The rolling unit was partially dipped and covered by polymer solution in a filled rectangular tank [10]. The applied high voltage generator unit was connected to the roller. The collector was positioned on the top and perpendicular to the rotation of the roller. The collector was a stationary unit which was grounded to create a potential difference. A nonwoven substrate material moved along the grounded collector electrode, thereby facilitating the production of the electrospun nanofibers as a continuous free streamlined process (Figure 6.8). As the applied voltage reaches and exceeds a critical field strength value, as the process is electrospinning and no difference from the conventional needle based electrospinning process in terms of concept, Taylor cones were formed which were ejected into polymer solution jets transforming into nanofibers travelling towards the collector electrode, and being collected in a collector present above the roller [11].
Electrospinning and Electrospraying in Polylactic Acid/Cellulose Composites
Published in Jyotishkumar Parameswaranpillai, Suchart Siengchin, Nisa V. Salim, Jinu Jacob George, Aiswarya Poulose, Polylactic Acid-Based Nanocellulose and Cellulose Composites, 2022
Juliana Botelho Moreira, Suelen Goettems Kuntzler, Ana Gabrielle Pires Alvarenga, Jorge Alberto Vieira Costa, Michele Greque de Morais, Loong-Tak Lim
The electrical potential influences the morphology and the size of the fibers and particles in the electrohydrodynamic processes. Taylor cone is formed when the applied electrical potential exceeds the surface tension of the polymer solution drop at the tip of the capillary (Songsurang et al., 2011). According to Park and Lee (2009), a critical electrical potential (CEp) is influenced by a solvent-polymer system. In general, to form electrosprayed particles, PLA was used with different solvents including chloroform, chloroform/ethanol, acetone, and chloroform/acetone, and the process parameters could be varied in flow rate (2–40 µL m−1), voltage (10–30 kV), distance from capillary to the collector (10–20 cm) and spinneret diameter (20–22 Gauge) (Ibili & Dasdemir, 2019). Values lower than CEp cause the polymeric solution to drip into the collector. For the formation of electrospun fibers, values far above the CEp provide a greater elongation of the solution and reduction in the diameter, as it increases the repulsive forces in the jet (Park & Lee, 2009). The flow rate together with the solution parameters can control the electrospinning behavior (Niu et al., 2020). Increasing flow rate tends to produce non-spherical particles with a high polydispersity (Ibili & Dasdemir, 2019; Niu et al., 2020). Similarly, at high flow rates, irregular fibers are formed, with larger diameters and the presence of residual solvent (Mercante et al., 2017).
Fabrication of Nanomaterials
Published in C. Anandharamakrishnan, S. Parthasarathi, Food Nanotechnology, 2019
R. Preethi, Leena Maria, J.A. Moses, C. Anandharamakrishnan
The electrospinning process is divided into two stages. In the first stage, polarization takes place in the polysaccharide solution under the impact of a high electric field (typically 1 kV/cm), the polymers form Taylor cones and jets. A Taylor cone is an aspect of the deformation of an immobile or pending droplet in an electric field, which brings down the droplet into a pointed shape. This instability of droplets may alter into a series of microscopic beads or a microscopically thin fluid jet at an appropriately high electric field strength. There is a formation of fiber in the second stage, which is collected in the collector phase. In the initial stage, the structure of the solution at the tip of the needle will likely determine the possibility to form a jet. The jet is elongated while traveling to the collector plate, due to the evaporation of the water, and then turns into a fiber (Figure 6.10) (Stijnman et al., 2011).
Electrospinning of cellulose acetate/graphene/nanoclay nanocomposite for textile wastewater filtration
Published in The Journal of The Textile Institute, 2023
Neda Sangani, Niloofar Eslahi, Mehdi Varsei, Hajar Ghanbari
Electrospinning is one of the simplest and most flexible techniques used for fabricating nanofibers by an electrical force. High speed, ease, and economic efficiency for making various nanofiber structures are the main advantages of the electrospinning process, among other fiber production techniques (Ding et al., 2019; Wang & Hsiao, 2016). During electrospinning, high voltage is applied between syringe containing spinning fluid and metallic collector. When the voltage reaches a critical value, the electrically charged fluid initiates a conical droplet (i.e. Taylor cone), from which the liquid jet is formed and elongated. Then, the electrically charged jet encounters a stretching-and-whipping process, during which the jet diameter declines from micrometers to as small as tens of nanometers. Finally, the as-spun nanofibers are accumulated on the surface of the grounded collector (Tiwari et al., 2021; Vaseashta & Bölgen, 2022).
Principles of preparing broad-wave reflective films supported by nanofiber networks
Published in Liquid Crystals, 2022
Miaomiao Jia, Zongcheng Miao, Dong Wang
In the electrospinning process, the jetting device is filled with a charge of polymer solution or molten liquid. Under the action of an applied electric field, the polymeric liquid held at the nozzle by surface tension droplet, induced by the electric field, collects an electric charge on the surface and is subjected to an electric field force in the opposite direction of the surface tension. When the electric field gradually increases, the droplet at the nozzle is elongated from a spherical shape to a cone shape, forming a so-called ‘Taylor cone’. The so-called ‘Taylor cone’ (Taylor cone). And when the electric field strength increases to ~ a critical value, the electric field force will overcome the liquid surface tension and is ejected from the ‘Taylor cone’. The jet is shocked by the high electric field, the jet is oscillated and unstable, resulting in a very high frequency of irregular spiral motion. In a high-speed oscillation; the plane stream is rapidly thinned and the solvent evaporates quickly, resulting in a jet stream of nano-sized fibres in diameter, which are scattered randomly on the collection device, forming a nonwoven fabric, or with a moving or rotating receiving device. Or a moving or rotating receiving device to obtain nanofiber oriented in a specific direction. The nanofiber mats are oriented in a certain direction with a moving or rotating receiving device [30–35].
Antibacterial electrospun nanomat from nigella/PVA system embedded with silver
Published in The Journal of The Textile Institute, 2021
Ayub Ali, Syed Maminul Islam, Md. Mohebbullah, Md. Nur Uddin, Md. Tofazzal Hossain, Sonjit Kumar Saha, Mohammad Salman Ibna Jamal
Nigella sativa is traditionally used in the Indian subcontinent, Arab countries and Europe (Hosseinzadeh et al., 2007) from time immemorial as a means of remedy for various ailments. One of the prominent characteristic of this herb is its wound healing property (Ghonime et al., 2011). In order to utilize the medicinal properties of this herb, it needs to be converted into a suitable form that can facilitate wound healing process. Electrospinning is a technique which can produce a nanomat using the extract of this seed. This method is popular as it is versatile, controllable and cost effective (Chronakis, 2005; Ramakrishna, 2005). This system consists of a polymer solution reservoir, a high voltage power supply and a grounded collector. An electric potential is applied to a polymeric drop coming out of the charged nozzle. The shape of the drop changes to conical shape called “Taylor cone”. The electrostatic forces overcome the surface tension with increasing the voltage and a charged jet ejects toward the collector with opposite charge. Later produced nanomat is collected from a collector usually wrapped with aluminum foil (Mary et al., 2013).