Spinning is a manufacturing process for creating

polymer A polymer () is a chemical substance, substance or material that consists of very large molecules, or macromolecules, that are constituted by many repeat unit, repeating subunits derived from one or more species of monomers. Due to their br ...

fibers Fiber (spelled fibre in British English; from ) is a natural or artificial substance that is significantly longer than it is wide. Fibers are often used in the manufacture of other materials. The strongest engineering materials often inco ...

. It is a specialized form of

extrusion Extrusion is a process used to create objects of a fixed cross section (geometry), cross-sectional profile by pushing material through a Die (manufacturing), die of the desired cross-section. Its two main advantages over other manufacturing pro ...

that uses a

spinneret A spinneret is a silk-spinning organ of a spider or the larva of an insect. Some adult insects also have spinnerets, such as those borne on the forelegs of Embioptera. Spinnerets are usually on the underside of a spider's opisthosoma, and ar ...

to form multiple continuous filaments..

Melt spinning

If the

is a

thermoplastic A thermoplastic, or thermosoftening plastic, is any plastic polymer material that becomes pliable or moldable at a certain elevated temperature and solidifies upon cooling. Most thermoplastics have a high molecular weight. The polymer chains as ...

then it can undergo melt spinning. The

molten Melting, or fusion, is a physical process that results in the phase transition of a substance from a solid to a liquid. This occurs when the internal energy of the solid increases, typically by the application of heat or pressure, which incre ...

polymer is extruded through a spinneret composed of capillaries where the resulting filament is solidified by cooling.

Nylon Nylon is a family of synthetic polymers characterised by amide linkages, typically connecting aliphatic or Polyamide#Classification, semi-aromatic groups. Nylons are generally brownish in color and can possess a soft texture, with some varieti ...

olefin In organic chemistry, an alkene, or olefin, is a hydrocarbon containing a carbon–carbon double bond. The double bond may be internal or at the terminal position. Terminal alkenes are also known as α-olefins. The International Union of Pu ...

polyester Polyester is a category of polymers that contain one or two ester linkages in every repeat unit of their main chain. As a specific material, it most commonly refers to a type called polyethylene terephthalate (PET). Polyesters include some natura ...

, saran, and sulfar are produced via this process.

Extrusion spinning

Pellets or granules of the solid polymer are fed into an

extruder 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 ...

. The pellets are compressed, heated and melted by an extrusion screw, then fed to a spinning pump and into the spinneret.

Direct spinning

The direct spinning process avoids the stage of solid polymer pellets. The polymer melt is produced from the raw materials, and then from the polymer finisher directly pumped to the spinning mill. Direct spinning is mainly applied during production of polyester fibers and filaments and is dedicated to high production capacity (>100 ton/day).

Solution spinning

If the

melting point The melting point (or, rarely, liquefaction point) of a substance is the temperature at which it changes state of matter, state from solid to liquid. At the melting point the solid and liquid phase (matter), phase exist in Thermodynamic equilib ...

of the polymer is higher than its degradation temperature, the polymer must undergo solution spinning techniques for fiber formation. The polymer is first dissolved in a

solvent A solvent (from the Latin language, Latin ''wikt:solvo#Latin, solvō'', "loosen, untie, solve") is a substance that dissolves a solute, resulting in a Solution (chemistry), solution. A solvent is usually a liquid but can also be a solid, a gas ...

, forming a spinning

solution Solution may refer to: * Solution (chemistry), a mixture where one substance is dissolved in another * Solution (equation), in mathematics ** Numerical solution, in numerical analysis, approximate solutions within specified error bounds * Solu ...

(sometimes called a "

dope Dope may refer to: Chemistry Biochemistry * Dope, a slang word for a euphoria-producing drug, particularly: ** Cocaine ** Cannabis (drug) ** Heroin ** Opioid * DOPE, or 1,2-Dioleoyl-''sn''-glycero-3-phosphoethanolamine, a phospholipid * Discret ...

"). The spinning solution then undergoes dry, wet, dry-jet wet, gel, or electrospinning techniques.

Dry spinning

A spinning solution consisting of polymer and a volatile solvent is extruded through a spinneret into an evaporating chamber. A stream of hot air impinges on the jets of spinning solution emerging from the spinneret, evaporating the solvent, and solidifying the filaments. Solution blow spinning is a similar technique where polymer solution is sprayed directly onto a target to produce a

nonwoven Nonwoven fabric or non-woven fabric is a fabric-like material made from staple fibre (short) and long fibres (continuous long), bonded together by chemical, mechanical, heat or solvent treatment. The term is used in the textile manufacturing in ...

fiber mat.

Wet spinning

Wet spinning is the oldest of the five processes. The polymer is dissolved in a spinning solvent where it is extruded out through a spinneret submerged in a coagulation bath composed of nonsolvents. The coagulation bath causes the polymer to

precipitate In an aqueous solution, precipitation is the "sedimentation of a solid material (a precipitate) from a liquid solution". The solid formed is called the precipitate. In case of an inorganic chemical reaction leading to precipitation, the chemic ...

in fiber form.

Acrylic Acrylic may refer to: Chemicals and materials * Acrylic acid, the simplest acrylic compound * Acrylate polymer, a group of polymers (plastics) noted for transparency and elasticity * Acrylic resin, a group of related thermoplastic or thermosettin ...

rayon 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 fiber, cellulose, such as wood and related agricultural products. It has t ...

aramid Aramid fibers, short for aromatic polyamide, are a class of heat-resistant and strong synthetic fibers. They are used in aerospace and military applications, for ballistic-rated bulletproof vest, body armor cloth, fabric and ballistic composites ...

modacrylic A modacrylic is a synthetic copolymer. Modacrylics are soft, strong, resilient and dimensionally stable. They can be easily dyed, show good press and shape retention, and are quick to dry. They have outstanding resistance to chemicals and solvents ...

, and

spandex Spandex, Lycra, or elastane is a synthetic fiber known for its exceptional elasticity. It is a polyether- polyurea copolymer that was invented in 1958 by chemist Joseph Shivers at DuPont. Name The name ''spandex'', which is an anagram of t ...

are produced via this process. A variant of wet spinning is dry-jet wet spinning, where the spinning solution passes through an air-gap prior to being submerged into the coagulation bath. This method is used in

Lyocell Lyocell is a semi-synthetic fibre 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, which is made by the more common viscose processe ...

spinning of dissolved

cellulose Cellulose is an organic compound with the chemical formula, formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of glycosidic bond, β(1→4) linked glucose, D-glucose units. Cellulose is an important s ...

, and can lead to higher polymer orientation due to the higher stretchability of the spinning solution versus the precipitated fiber.

Gel spinning

Gel spinning, also known as semi-melt spinning, is used to obtain high strength or other special properties in the fibers. Instead of wet spinning, which relies on precipitation as the main mechanism for solidification, gel spinning relies on temperature-induced physical

gelation In polymer chemistry, gelation (gel transition) is the formation of a gel from a system with polymers. Branched polymers can form links between the chains, which lead to progressively larger polymers. As the linking continues, larger branched p ...

as the primary method for solidification. The resulting gelled fiber is then swollen with the spinning solvent (similar to

gelatin dessert Gelatin desserts are desserts made with a sweetened and flavoured processed collagen product (gelatin), which makes the dessert "set" from a liquid to a soft elastic solid gel. This kind of dessert was first recorded as "jelly" by Hannah Glas ...

s) which keeps the polymer chains somewhat bound together, resisting relaxation which is prevalent in wet spinning. The high solvent retention allows for ultra-high drawing as with

ultra high molecular weight polyethylene Ultra-high-molecular-weight polyethylene (UHMWPE, UHMW) is a subset of the thermoplastic polyethylene. Also known as high-modulus polyethylene (HMPE), it has extremely long chains, with a molecular mass typically between 2 and 6 million amu. The l ...

(UHMWPE) (e.g., Spectra^®) to produce fibers with a high degree of orientation, which increases fiber strength. The fibers are first cooled either with air or in a liquid bath to induce gelation, then the solvent is removed through ageing in a nonsolvent, or during the drawing stage. Some high strength

polyethylene Polyethylene or polythene (abbreviated PE; IUPAC name polyethene or poly(methylene)) is the most commonly produced plastic. It is a polymer, primarily used for packaging (plastic bags, plastic films, geomembranes and containers including bott ...

and

polyacrylonitrile Polyacrylonitrile (PAN) is a synthetic, semicrystalline organic polymer resin, with the linear formula (CH2CHCN)n. Almost all PAN resins are copolymers with acrylonitrile as the main monomer. PAN is used to produce large variety of products in ...

fibers are produced via this process.

Electrospinning

Electrospinning uses an electrical charge to draw very fine (typically on the micro or nano scale)

fibre Fiber (spelled fibre in British English; from ) is a natural or artificial substance that is significantly longer than it is wide. Fibers are often used in the manufacture of other materials. The strongest engineering materials often incorp ...

s from a liquid - either a polymer solution or a polymer melt. Electrospinning shares characteristics of both

electrospray The name electrospray is used for an apparatus that employs electricity to disperse a liquid or for the fine aerosol resulting from this process. High voltage is applied to a liquid supplied through an emitter (usually a glass or metallic capilla ...

ing and conventional solution dry spinningZiabicki, A. ''Fundamentals of fiber formation'', John Wiley and Sons, London, 1976, . 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.

Melt electrospinning 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 ...

is also practiced; this method ensures that no solvent can be carried over into the final product.Hutmacher DW & Dalton PD (2011) Melt Electrospinning. Chem Asian J, 6, 44-5.

Post-spin processes

Drawing

Finally, the fibers are drawn to increase strength and orientation. This may be done while the polymer is still solidifying or after it has completely cooled.

References

{{Authority control Plastics industry Synthetic fibers Textile engineering