Electrospinning is a fibre spinning technique that produces materials with small fibres from micro- to nanometers fibre diameters, high surface area, and an interconnected fibrous network desirable for a range of applications. Electrospinning is a well-recognized and effective technique to produce fibres from the electrostatically driven jets of polymer solution or melts [15].
1.1. History of electrospinning.
The term “electrospinning”, derived from “electrostatic spinning”, has been used only in 1994 but existence of the process itself can be proven back since XVIII century. However, it started to develop faster in XX century [4].
In 1900 John Francis Cooley filled the first electrospinning patent where he proposed four types of indirectly
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Before reaching the collecting screen, the solution jet evaporates or solidifies, and is collected as an interconnected web of small fibres. One electrode is placed into the spinning solution/melt and the other attached to the collector. In most cases, the collector is simply grounded. The electric field is subjected to the end of the capillary tube that contains the solution fluid held by its surface tension. This induces a charge on the surface of the liquid. Mutual charge repulsion and the contraction of the surface charges to the counter electrode cause a force directly opposite to the surface tension. As the intensity of the electric field is increased, the hemispherical surface of the fluid at the tip of the capillary tube elongates to form a conical shape known as the Taylor cone. Further increasing the electric field, a critical value is attained with which the repulsive electrostatic force overcomes the surface tension and the charged jet of the fluid is ejected from the tip of the Taylor cone. The discharged polymer solution jet undergoes an instability and elongation process, which allows the jet to become very long and thin. Meanwhile, the solvent evaporates, leaving behind a charged polymer fibre. In the case of the melt the discharged jet solidifies when it travels in the air …show more content…
At low voltages, bead free spinning is possible as the jet originates from the Taylor cone itself rather than from the surface of the liquid within the needle tip when voltage exceeds the typical spinning range. These large beaded structures at higher voltages are generated when the Taylor cone recedes at the tip of the needle. Beads formation exceeds according to the increase of the electric field strength. Increased voltages not only produce beaded structures but also lead to the formation of several large diameter jets [4], [11], [12],
Repeat for each trial. Rinse volumetric pipette with vinegar and drain into the waste beaker. Weigh and record the mass of each 200mL beaker. Add 10.00mL of vinegar into each beaker and weigh them and record their again. Add 50mL of de-ionized water to the beakers and place them under the drop counter on top of a stir plate, submerging the pH meter into the solution. Place the stir bar into the beaker and carefully turn on the stir plate so that the stir bar spins without splashing or hitting the sides of the beaker or the pH
An electron gun is present in a Scanning Electron Microscope to generate a beam of electrons in a high vacuum column. With the help of an accelerating voltage of between 1.0 to 30 kV, the emitted electrons are converted into a coherent beam by using a system of electromagnetic coils or lenses. Then the beam passed down through the main electron gun column into the specimen chamber. Here it is focused onto a fine spot. Then the surface of the sample is scanned rapidly.
The motor is turned on, the lower part begins turning its belt. The belt is made of rubber so it attracts more electricity than a regular belt would. The lower part builds to have a negative charge and the belt makes a positive charge. The reason this happens is because in the belt there is a silicon part that is built in the belt making it more negative than rubber, the lower part is taking electrons from the belt as it goes over the roller. Causing the electricity to go up into the sphere and flowing through it.
The first term that I noted during the movie was Conductive Polymers. Conductive polymers are almost always organic meaning a large class of chemical compounds whose molecules contain carbon. These polymers have extended delocalized bonds which are bonds found in a molecule that do not belong to a single atom or covalent bond. They are conjugated systems of double bonds and in a aromatic systems. The conjugated systems are atoms covalently bonded with alternating single and double bonds. When the electrons are removed or added into the valence bands the electrical conductivity increases. The conductive polymer has a low conductivity until the electron is removed from the valence band called (p-doping) or (n-doping) until it becomes more conductive. The movement of the charges is what is responsible for electrical conductivity. These polymers are plastic which are organic polymers and with mechanical properties such as flexibility and elasticity.
How the polymer chains are put together is important, as it improves the properties of the material. The flexibility, strength and stiffness of Kevlar fiber, is dependent on the orientation of the polymer chains. Kevlar fiber is an arrangement of molecules, oriented parallel to each other. This orderly, untangled arrangement of molecules is described as a “Crystalline Structure”. A manufacturing process known as ‘Spinning’ is needed to achieve this crystallinity structure.
Thin solid films were probably first obtained in 1838 by electrolysis. They were systematically prepared by Faraday in 1857.
An electromagnet is a magnet that uses an electric current to attract metal, such as wiring a battery to coils on a ferromagnetic material. Electromagnets are also used in many different ways, some you may not know use electromagnets. Electromagnets are used in places like scrapyards to pick up extremely heavy objects such as cars, etc (Jessa 2009). CAT scanners have electromagnets in them to see the things that they need to see. Electr...
John Kay, an English weaver invented the flying shuttle, a product that could cut cotton twice as fast. When other inventors saw what Kay had made, they wanted to do the same. One problem still remained. Yarn was not being fed fast enough through the weaver, but in 1769, two new inventions solved the problem. The spinning jenny and the water-powered frame, both of which fed yarn through the flying shuttle faster. Cleaning the cotton was a boring and time consuming job, so in 1793, Eli Whitney invented the cotton gin. The gin cleaned cotton up to 50 times faster than a human could.
The electric guitar was first made in the Oklahoma. This electric guitar design that was made in Oklahoma was the first of its kind and changed music for everyone. The simplicity of the electric guitar surprised many people. All electric guitars since then have been based on this simple guitar design. Many famous musicians such as Jimi Hendrix, Eric Clapton and many other have made electric guitar more affordable and widely available.
When the ECU sends a pulse to the injector, which closes the electrical circuit, the injector’s solenoid creates a magnetic field. This magnetic field attracts the needle’s magnet opening the exit orifice and letting flow the fuel.
There are two popular ways of creating nylon for fiber applications. One, ¡°molecules with an acid (COOH) group on each end are reacted with molecules containing amine (NH©ü) groups on each end.¡± The nylon 6,6 is made in this fashion. The other common way of making nylon fibers is by polymerizing a compound containing an amine at one end and an acid at the other, to form a chain with reoccurring groups of (-NH-[CH©ü]n-CO-)x. If the x=5, the fiber is named nylon 6 (Nylon Fiber).
Create wells: put a comb template in the middle of the tray; wait until the mixture becomes solid. After, remove the comb standing straight. 4. Remove rubber ends: transfer the gel tray into the horizontal electrophoresis and fill it with the concentrated electrophoresis buffer. 5. Materials and methods: Experiment: 1st, prepared milk samples should be already done by the teacher.
...o generate an alternating magnetic field. This alternating field is the driving force that causes the cone to repel. The coil receives many different ranges of impulses which can cause the cone to move very violently or not at all.
Edison searched for the proper "filament" or wire, that would give good light when electricity flowed through it. He sent people to the jungles of the Amazon and forests of Japan in his search for a perfect filament material. He tested over 6,000 vegetable growths (baywood, boxwood, hickory, cedar, flax, bamboo) as filament material.
The electrostatic precipitator (ESP) is a machine used in factories, to clean out the waste solid particle, for example ash from the exhaust gas, allowing clean exhaust gas exit through the chimney. The electrostatic precipitator functions by using first allow the exhaust gas with the waste solid particles pass through the Nozzle as shown in the diagram below. Then the exhaust gas passes through inlet gas distribution, which evenly distributes the gas as shown below in a turquoise color, and starts going through the Discharge electrodes and the collector plates, which is shown in the diagram red and blue respectively. The discharge electrodes, which are powered by high voltage direct current, ionize the gas along with the other solid waste particles negatively. The collector plates are also charged with high voltage electricity, but it is positively charged, therefore attracting the negatively charged solid particle, because oppositely charged particles attract. This allows the clean exhaust gas pass through the other end, while the solid waste particles are trapped in the collector plates. Eventually when there are enough solid waste particles collected on the collector plates, the collect plates shakes off the collected waste, where it drops to the bottom of the shaft as shown in the diagram as “Hopper”.