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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
Electrohydrodynamic processes, such as electrospraying and electrospinning, are methods used for the production of particles and fibers, respectively (Garavand et al., 2019; Katouzian & Jafari, 2016; Mendes et al., 2017). These processes allow the production of materials at micron, submicron, and nano scales of various morphology by manipulating the properties of the polymeric solution and the processing parameters. Moreover, these nonthermal processes do not require the application of heat and are hence advantageous for many heat-labile materials (Mendes et al., 2017). The electrohydrodynamic processes are adaptable for different materials, such as natural/synthetic polymers, ceramics, and composites. Typical equipment for electrohydrodynamic processes consists of elements of a high voltage supply, a positive displacement pump for the injection of the polymeric solution, and an electrically grounded collector for the deposition of electrospun fibers/electrosprayed particles (Figure 14.1).
Macroscopic models for electrospinning
Published in A. K. Haghi, Lionello Pogliani, Francisco Torrens, Devrim Balköse, Omari V. Mukbaniani, Andrew G. Mercader, Applied Chemistry and Chemical Engineering, 2017
Shima. Maghsoodlou, S. Poreskandar
Electrospinning is an example of an electrohydrodynamic phenomenon. In electrohydrodynamics (EHD), charges induce fluid motion within an electric field. During the process, the transport and distribution of these charges generate stresses that result in the movement of the fluid. The leaky dielectric EHD model is an appropriate model to use because the model of the fluid’s electrical properties as a poorly conducting liquid is comparable to the behavior of most polymer solutions, the most commonly used type of fluid in electrospinning.7, 8 Hohman et al.2 built an electrohydrodynamic instability theory and predicted that under favorable conditions, a nonaxisymmetric instability prevails over the familiar Rayleigh instability and a varicose instability due to electric charges. In theoretical work to date, the rheology ofthe polymer jet has been represented by a Newtonian viscosity,2, 3 a power-law viscosity,1 and the linear Maxwell equation.4, 5
Introduction
Published in Mohamed Gad-el-Hak, MEMS, 2005
electric potential from a pressure-driven flow in a charged microchannel [Hunter, 1981; Scales et al., 1992]. Sedimentation potential is the generation of an electric potential that results from the sedimentation (e.g., due to gravity) of a charged particle [Russel et al., 1999]. All of the phenomena classified under the term electrokinetics are manifestations of the electrostatic component of the Lorentz force (on ions and surface charges) and Newton's second law of motion. These interactions between charged particles and electric fields often involve electric double layers formed at liquid/solid interfaces, and an introduction to this phenomenon is presented below. Electrokinetic flows are in general a subclass of electrohydrodynamic flows [Melcher, 1981; Saville, 1997 ], which describe the general coupling between electric fields and fluid flow. Electrokinetic systems are distinguishable in that they involve liquid electrolyte solutions and the presence of electrical double layers (i.e., involve electrophoresis and electroosmosis).
Recent advances in micro-sized oxygen carriers inspired by red blood cells
Published in Science and Technology of Advanced Materials, 2023
Qiming Zhang, Natsuko F. Inagaki, Taichi Ito
Electrospinning and electrospraying are electrohydrodynamic processes in which single or multiple electrically charged polymer solution jets are sprayed or spun for the formation of nano-sized to micro-sized fibers and particles, respectively [64]. Usually, the particles or fibers form and solidify and are collected in an ultrasonic aqueous bath before solvent evaporation. This technique has been extensively used in the last decade to prepare AOCs. Single axial electrospinning or electrospraying is used to generate microfibers or microparticles with single phases. For instance, Erlane et al. [65] produced a polycaprolactone (PCL) microparticle loaded with nano-sized calcium PO (CPO) oxygen-generating microparticles by electrospraying at a positive voltage of 12 kV. Those microparticles ranged in size from 5 to 15 μm and were later encapsulated together with cells in the hydrogel for enhanced cell expansion. Similarly, Sajedeh et al. [66] fabricated polylactic-co-glycolic acid (PLGA) microparticles loaded with nano-CPO with average diameter of 5.3 μm by electrospraying at a constant voltage of 15 kV. Notably, the electrosprayed PLGA/CPO microparticles presented a biconcave disk-like morphology in spite of a wide size distribution. Morais et al. [67] prepared mono-dispersed PCL/CPO microparticles with diameters of 17.0 ± 0.3 μm at a positive voltage of 12kV.
Wound healing and antibacterial capability of electrospun polyurethane nanofibers incorporating Calendula officinalis and Propolis extracts
Published in Journal of Biomaterials Science, Polymer Edition, 2023
Masoud Davoudabadi, Shoreh Fahimirad, Ali Ganji, Hamid Abtahi
When the size of a material is reduced from micrometers to nanometers, the resulting properties can change dramatically. These properties include huge surface-to-volume ratios, flexibility in surface functionalities, and superior mechanical performance (such as stiffness and tensile strength). These exceptional properties make polymer nanofibers ideal candidates for many critical applications in fields such as air and water purification, drug delivery, tissue engineering, and regenerative medicine [11]. Electrospinning involves an electrohydrodynamic process. A liquid droplet is electrified to produce a jet. It is followed by stretching and elongation to make fiber(s) [12–17].
Electrohydrodynamic drying: Effects on food quality
Published in Drying Technology, 2021
Electrohydrodynamics is a branch of fluid mechanics, dealing with the movement of fluids under the influence of an electric field. Electrohydrodynamic drying exploits the properties of a high voltage corona discharge, resulting in ionization of air and “corona” or “ionic” wind. The electric field drives the ions from the discharge electrode to the collecting electrode (primary airflow). The secondary airflow is produced by the transfer of momentum from these high-speed ions to the surrounding air molecules. The combined effect of the electric field-induced airflow and secondary airflow is crucial in EHD drying.[8,9] According to Singh et al.,[6] the ionic wind continuously interrupts the saturated boundary layer on the surface of food materials, accelerating water evaporation. The force required for this moisture migration is contributed by the electric field and charge density. The cell membrane itself acts as a dielectric material that maintains a potential difference under normal conditions. Under the influence of an external electric field, the charges are accumulated on the inner and outer sides of the membrane to create an internal electric field.[10] In a nonuniform electric field water molecules are dragged from weaker to stronger fields.[11] Furthermore, the water dipoles orient in the direction of the electric field, lowering the entropy. These entropy changes and evaporative cooling are responsible for the low temperature of EHD dried materials.[12] EHD drying depends on various factors like the voltage, current, electric field strength, material, and geometrical properties of electrode system.[13] The effect of these factors on the EHD drying of plant-based foods has been reviewed in detail by Bashkir et al.[8]