Electrospinning of clean cloth involves fluid drawing i […]
Electrospinning of clean cloth involves fluid drawing in the form of molten polymer or polymer solution. However, unlike the traditional method that uses external force to push the polymer melt through the mold, electrospinning uses the charge applied to the fluid to generate a stretching force and extends it to a collector with a voltage gradient, as long as the voltage is large enough , Polymer spinning will appear in polymer droplets. The entanglement of polymer chains in the solution will prevent the electrostatic spinning spinnerets in the clean cloth from breaking. The molten polymer used in traditional fiber manufacturing is cooled and solidified in the air, while the polymer solution used in the electrostatic spinning of the dust-free cloth depends on the volatilization of the solvent to achieve the effect of solidifying the polymer to form the polymer fiber.
There are many applications of electrospun materials and fibers in clean cloths, and their applications must also consider the unique properties of various materials. By improving the electrospinning process, electrospun fibers with ideal morphology and properties can be obtained. When used as a composite material, nanofibers can be used alone or as a reinforcing material for the matrix. In the process of preparing ceramic fibers, post-treatment of the electrospun fibers in the dust-free cloth is necessary. Therefore, in order to achieve a specific application, a preliminary understanding of the different types of materials is necessary to obtain the ideal electrospun fiber.
Polymers are long-chain molecules composed of repeating units connected by covalent bonds. For example, polyethylene is composed of seven CH. cH. It is composed of repeating units. This kind of unit is also called a monomer, and the monomer must have an active functional group such as an amino group, or a double bond that can covalently connect the repeating unit under suitable conditions. The backbone of the polymer chain is formed by the connection of such monomers. There are usually weak secondary bonds that can slide between the molecular chains. Polymers have a wide range of uses. Most polymers are relatively easy to synthesize and are relatively inexpensive due to their simple components.
A widely accepted classification of polymers is based on their response to heat. This classification divides polymers into two basic types: thermoplastic and thermoset. When the thermoplastic polymer is heated, the linear polymer will melt, and will solidify when cooled, and such heating and cooling can be repeated many times without affecting the properties of the polymer. Thermoplastic polymers include polyethylene, polystyrene, and polyvinyl chloride. However, when the polymer is heated, its structure is greatly affected by temperature, and the polymer will be distorted and deformed if the temperature exceeds a certain temperature for a period of time. For thermosetting polymers, once heated, crosslinks of polymer chains will be formed, and continued heating can only cause degradation of the polymer. This means that such polymers have a higher upper temperature limit. Thermosetting polymers include phenolic plastics, urea and epoxy resins.
In the polymer matrix, usually both crystalline regions and amorphous regions exist. The ratio of the two zones determines the properties of the polymer. If the arrangement of linear molecules in the polymer is completely disordered, the polymer is considered to be amorphous, while the crystalline polymer chain is an ordered structure. For crystalline polymers, the widely accepted theory is the folded chain theory. The polymer chains are first folded and stacked on top of each other, and then are gathered together by an amorphous tie structure to form crystals. Subsequently, the polymer chains are twisted and form ribbon-shaped supramolecules called spherulites. Polymers with high crystallinity have high yield strength, modulus and hardness. When the crystalline polymer is stretched, the polymer chains are oriented in the direction of the stress and destroy the spherulitic structure, and necking can be observed. Crystalline polymers also have better abrasion resistance and chemical resistance, but crystalline polymers are more brittle.
