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Rayon, also called viscose and commercialised in some countries as sabra silk or cactus silk, is a semi-synthetic fiber, made from natural sources of regenerated cellulose, such as wood and related agricultural products. It has the same molecular structure as cellulose. Many types and grades of viscose fibers and films exist. Some imitate the feel and texture of natural fibers such as silk, wool, cotton, and linen. The types that resemble silk are often called artificial silk. It is used to make textiles for clothing and other purposes.
In biochemistry, cellulose acetate refers to any acetate ester of cellulose, usually cellulose diacetate. It was first prepared in 1865. A bioplastic, cellulose acetate is used as a film base in photography, as a component in some coatings, and as a frame material for eyeglasses; it is also used as a synthetic fiber in the manufacture of cigarette filters and playing cards. In photographic film, cellulose acetate film replaced nitrate film in the 1950s, being far less flammable and cheaper to produce.
Lyocell is a semi-synthetic fiber used to make textiles for clothing and other purposes. It is a form of regenerated cellulose made by dissolving pulp and dry jet-wet spinning. Unlike rayon made by some of the more common viscose processes, Lyocell production does not use carbon disulfide, which is toxic to workers and the environment. Lyocell was originally trademarked as Tencel in 1982.
Extrusion is a process used to create objects of a fixed cross-sectional profile by pushing material through a die of the desired cross-section. Its two main advantages over other manufacturing processes are its ability to create very complex cross-sections; and to work materials that are brittle, because the material encounters only compressive and shear stresses. It also creates excellent surface finish and gives considerable freedom of form in the design process.
Although PET is used in several applications,, as of 2022 only bottles are collected at a substantial scale. The main motivations have been either cost reduction or recycle content of retail goods. An increasing amount is recycled back into bottles, the rest goes into fibres, film, thermoformed packaging and strapping. After sorting, cleaning and grinding, 'bottle flake' is obtained, which is then processed by either:
Electrospinning is a fiber production method that uses electric force to draw charged threads of polymer solutions or polymer melts up to fiber diameters in the order of some hundred nanometers. Electrospinning shares characteristics of both electrospraying and conventional solution dry spinning of fibers. The process does not require the use of coagulation chemistry or high temperatures to produce solid threads from solution. This makes the process particularly suited to the production of fibers using large and complex molecules. Electrospinning from molten precursors is also practiced; this method ensures that no solvent can be carried over into the final product.
Polyamide-imides are either thermosetting or thermoplastic, amorphous polymers that have exceptional mechanical, thermal and chemical resistant properties. Polyamide-imides are used extensively as wire coatings in making magnet wire. They are prepared from isocyanates and TMA in N-methyl-2-pyrrolidone (NMP). A prominent distributor of polyamide-imides is Solvay Specialty Polymers, which uses the trademark Torlon.
Acrylic fibers are synthetic fibers made from a polymer (polyacrylonitrile) with an average molecular weight of ~100,000, about 1900 monomer units. For a fiber to be called "acrylic" in the US, the polymer must contain at least 85% acrylonitrile monomer. Typical comonomers are vinyl acetate or methyl acrylate. DuPont created the first acrylic fibers in 1941 and trademarked them under the name Orlon. It was first developed in the mid-1940s but was not produced in large quantities until the 1950s. Strong and warm acrylic fiber is often used for sweaters and tracksuits and as linings for boots and gloves, as well as in furnishing fabrics and carpets. It is manufactured as a filament, then cut into short staple lengths similar to wool hairs, and spun into yarn.
Ultra-high-molecular-weight polyethylene is a subset of the thermoplastic polyethylene. Also known as high-modulus polyethylene (HMPE), it has extremely long chains, with a molecular mass usually between 3.5 and 7.5 million amu. The longer chain serves to transfer load more effectively to the polymer backbone by strengthening intermolecular interactions. This results in a very tough material, with the highest impact strength of any thermoplastic presently made.
Nonwoven fabric is a fabric-like material made from staple fibre (short) and long fibres, bonded together by chemical, mechanical, heat or solvent treatment. The term is used in the textile manufacturing industry to denote fabrics, such as felt, which are neither woven nor knitted. Some non-woven materials lack sufficient strength unless densified or reinforced by a backing. In recent years, non-wovens have become an alternative to polyurethane foam.
Nanofibers are fibers with diameters in the nanometer range. Nanofibers can be generated from different polymers and hence have different physical properties and application potentials. Examples of natural polymers include collagen, cellulose, silk fibroin, keratin, gelatin and polysaccharides such as chitosan and alginate. Examples of synthetic polymers include poly(lactic acid) (PLA), polycaprolactone (PCL), polyurethane (PU), poly(lactic-co-glycolic acid) (PLGA), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), and poly(ethylene-co-vinylacetate) (PEVA). Polymer chains are connected via covalent bonds. The diameters of nanofibers depend on the type of polymer used and the method of production. All polymer nanofibers are unique for their large surface area-to-volume ratio, high porosity, appreciable mechanical strength, and flexibility in functionalization compared to their microfiber counterparts.
Plastics extrusion is a high-volume manufacturing process in which raw plastic is melted and formed into a continuous profile. Extrusion produces items such as pipe/tubing, weatherstripping, fencing, deck railings, window frames, plastic films and sheeting, thermoplastic coatings, and wire insulation.
Olefin fiber is a synthetic fiber made from a polyolefin, such as polypropylene or polyethylene. It is used in wallpaper, carpeting, ropes, and vehicle interiors.
Nanofabrics are textiles engineered with small particles that give ordinary materials advantageous properties such as superhydrophobicity, odor and moisture elimination, increased elasticity and strength, and bacterial resistance. Depending on the desired property, a nanofabric is either constructed from nanoscopic fibers called nanofibers, or is formed by applying a solution containing nanoparticles to a regular fabric. Nanofabrics research is an interdisciplinary effort involving bioengineering, molecular chemistry, physics, electrical engineering, computer science, and systems engineering. Applications of nanofabrics have the potential to revolutionize textile manufacturing and areas of medicine such as drug delivery and tissue engineering.
A spinneret is a device used to extrude a polymer solution or polymer melt to form fibers. Streams of viscous polymer exit via the spinneret into air or liquid leading to a phase inversion which allows the polymer to solidify. The individual polymer chains tend to align in the fiber because of viscous flow. This airstream liquid-to-fiber formation process is similar to the production process for cotton candy. The fiber production process is generally referred to as "spinning". Depending on the type of spinneret used, either solid or hollow fibers can be formed. Spinnerets are also used for electrospinning and electrospraying applications. They are sometimes called coaxial needles, or coaxial emitters.
Melt electrospinning is a processing technique to produce fibrous structures from polymer melts for applications that include tissue engineering, textiles and filtration. In general, electrospinning can be performed using either polymer melts or polymer solutions. However, melt electrospinning is distinct in that the collection of the fiber can very focused; combined with moving collectors, melt electrospinning writing is a way to perform 3D printing. Since volatile solvents are not used, there are benefits for some applications where solvent toxicity and accumulation during manufacturing are a concern.
A die in polymer processing is a metal restrictor or channel capable of providing a constant cross sectional profile to a stream of liquid polymer. This allows for continuous processing of shapes such as sheets, films, pipes, rods, and other more complex profiles. This is a continuous process, allowing for constant production, as opposed to a sequential (non-constant) process such as injection molding.
Hollow fiber membranes (HFMs) are a class of artificial membranes containing a semi-permeable barrier in the form of a hollow fiber. Originally developed in the 1960s for reverse osmosis applications, hollow fiber membranes have since become prevalent in water treatment, desalination, cell culture, medicine, and tissue engineering. Most commercial hollow fiber membranes are packed into cartridges which can be used for a variety of liquid and gaseous separations.
Melt blowing is a conventional fabrication method of micro- and nanofibers where a polymer melt is extruded through small nozzles surrounded by high speed blowing gas. The randomly deposited fibers form a nonwoven sheet product applicable for filtration, sorbents, apparels and drug delivery systems. The substantial benefits of melt blowing are simplicity, high specific productivity and solvent-free operation. Choosing an appropriate combination of polymers with optimized rheological and surface properties, scientists have been able to produce melt-blown fibers with an average diameter as small as 36 nm.
Hydrogel fiber is a hydrogel made into a fibrous state, where its width is significantly smaller than its length. The hydrogel's specific surface area at fibrous form is larger than that of the bulk hydrogel, and its mechanical properties also changed accordingly. As a result of these changes, hydrogel fiber has a faster matter exchange rate and can be woven into different structures.
References
- 1 2 3 4 5 Manufacturing: Synthetic and Cellulosic Fiber Formation Technology, archived from the original on 1998-05-26, retrieved 2008-11-19.
- ↑ Daristotle, John L.; Behrens, Adam M.; Sandler, Anthony D.; Kofinas, Peter (2016-12-28). "A Review of the Fundamental Principles and Applications of Solution Blow Spinning". ACS Applied Materials & Interfaces. 8 (51): 34951–34963. doi:10.1021/acsami.6b12994. ISSN 1944-8252. PMC 5673076 . PMID 27966857.
- ↑ Ziabicki, A. Fundamentals of fiber formation, John Wiley and Sons, London, 1976, ISBN 0-471-98220-2.
- ↑ Nagy,Z.K.; Balogh,A.; et al. (2012). "Solvent-free melt electrospinning for preparation of fast dissolving drug delivery system and comparison with solvent-based electrospun and melt extruded systems". Journal of Pharmaceutical Sciences. 102 (2): 508–517. doi:10.1002/jps.23374. PMID 23161110.
- ↑ Hutmacher DW & Dalton PD (2011) Melt Electrospinning. Chem Asian J, 6, 44-5.
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