Polyacrylonitrile

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Polyacrylonitrile
Polyacrylnitril.svg
Names
IUPAC name
poly(1-acrylonitrile)
Other names
Polyvinyl cyanide [1]
Creslan 61
Properties
(C3H3N)n
Molar mass 53.0626 ± 0.0028 g/mol
C 67.91%, H 5.7%, N 26.4%
AppearanceWhite solid
Density 1.184 g/cm3
Melting point 300 °C (572 °F; 573 K)
Boiling point Degrades
Insoluble
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Polyacrylonitrile (PAN) is a synthetic, semicrystalline organic polymer resin, with the linear formula (CH2CHCN)n. [2] Almost all PAN resins are copolymers with acrylonitrile as the main monomer. PAN is used to produce large variety of products including ultra filtration membranes, hollow fibers for reverse osmosis, fibers for textiles, and oxidized PAN fibers. PAN fibers are the chemical precursor of very high-quality carbon fiber. PAN is first thermally oxidized in air at 230 °C to form an oxidized PAN fiber and then carbonized above 1000 °C in inert atmosphere to make carbon fibers found in a variety of both high-tech and common daily applications such as civil and military aircraft primary and secondary structures, missiles, solid propellant rocket motors, pressure vessels, fishing rods, tennis rackets and bicycle frames. It is a component repeat unit in several important copolymers, such as styrene-acrylonitrile (SAN) and acrylonitrile butadiene styrene (ABS) plastic.

Contents

History

Polyacrylonitrile (PAN) was first synthesized in 1930 by Hans Fikentscher and Claus Heuck in the Ludwigshafen works of the German chemical conglomerate IG Farben. [3] However, as PAN is non-fusible, and did not dissolve in any of the industrial solvents being used at the time, further research into the material was halted. [4] In 1931, Herbert Rein, head of polymer fiber chemistry at the Bitterfeld plant of IG Farben, obtained a sample of PAN while visiting the Ludwigshafen works. [5] He found that pyridinium benzylchloride, an ionic liquid, would dissolve PAN. [6] He spun the first fibers based on PAN in 1938, using aqueous solutions of quaternary ammonium sodium thiocyanate and aluminum perchlorate for the production process and considered other solvents including DMF. However, commercial introduction was delayed due to the wartime stresses on infrastructure, inability to melt the polymer without degradation, and solvents to allow solution processing were not known yet. [7] [8] The first mass production run of PAN fiber was in 1946 by American chemical conglomerate DuPont. The German intellectual property had been stolen in Operation Paperclip. The product, branded as Orlon, was based on a patent filed exactly seven days after a nearly identical German claim. [9] [ failed verification ] In the German Democratic Republic (GDR), industrial polyacrylonitrile fibre production was started in 1956 at the VEB Film- und Chemiefaserwerk Agfa Wolfen due to the preliminary work of the "Wolcrylon" collective ( de:Max Duch , Herbert Lehnert et al.). Prior to this, the preconditions for the production of the raw materials had been created at the Buna Werke Schkopau (Polyacrylonitrile) and Leuna works (Dimethylformamide). [10] In the same year, the collective was awarded the GDR's National Prize II Class for Science and Technology for its achievements. [11]

Physical properties

Although it is thermoplastic, polyacrylonitrile does not melt under normal conditions. It degrades before melting. It melts above 300 °C if the heating rates are 50 degrees per minute or above. [12]

Glass transition temperature is around 95 °C and fusion temperature is at 322 °C. PAN is soluble in polar solvents, such as dimethylformamide, dimethylacetamide, ethylene and propylene carbonates, and in aqueous solutions of sodium thiocyanate, zinc chloride or nitric acid. [13] Solubility parameters: 26.09 MPa1/2 (25 °C) are 25.6 to 31.5 J1/2 cm−3/2. Dielectric constants: 5.5 (1 kHz, 25 °C), 4.2 (1 MHz, 25 °C).Can behave as branched as well as linear polymer.

Synthesis

Most commercial methods for the synthesis of PAN are based on free radical polymerization of acrylonitrile. [14] In most of the cases, 10% amounts of other vinyl comonomers are also used (1–10%) along with AN depending on the final application. Comonomers include acrylic acid, acrylamide, allyl compounds, and sulfonated styrene. [2] Anionic polymerization also can be used for synthesizing PAN. For textile applications, molecular weight in the range of 40,000 to 70,000 is used.[ citation needed ] For producing carbon fiber higher molecular weight is desired. [15]

In the production of carbon fibers containing 600 tex (6k) PAN tow, the linear density of filaments is 0.12 tex and the filament diameter is 11.6 μm which produces a carbon fiber that has the filament strength of 417 kgf/mm2 and binder content of 38.6%. This data is demonstrated in the Indexes for Experimental Batches of PAN Precursor and Carbon Fibers Made from It table. [16]

Applications

Homopolymers of polyacrylonitrile have been used as fibers in hot gas filtration systems, outdoor awnings, sails for yachts, and fiber-reinforced concrete. Copolymers containing polyacrylonitrile are often used as fibers to make knitted clothing like socks and sweaters, as well as outdoor products like tents and similar items. If the label of a piece of clothing says "acrylic", then it is made out of some copolymer of polyacrylonitrile. It was made into the spun fiber at DuPont in 1942 and marketed under the name of Orlon. Acrylonitrile is commonly employed as a comonomer with styrene, e.g. acrylonitrile, styrene and acrylate plastics. Labelling of items of clothing with acrylic (see acrylic fiber) means the polymer consists of at least 85% acrylonitrile as the monomer. A typical comonomer is vinyl acetate, which can be solution-spun readily to obtain fibers that soften enough to allow penetration by dyes. The advantages of the use of these acrylics are that they are low-cost compared to natural fiber, they offer better sunlight resistance and have superior resistance to attack by moths. Acrylics modified with halogen-containing comonomers are classified as modacrylics, which by definition contain more than PAN percentages between 35-85%. Incorporation of halogen groups increases the flame resistance of the fiber, which makes modacrylics suitable for the use in sleepwear, tents and blankets. Some mattresses also use them to meet the flame resistance requirements in North America. [17] However, the disadvantage of these products is that they are costly and can shrink after drying.

PAN absorbs many metal ions and aids the application of absorption materials. Polymers containing amidoxime groups can be used for the treatment of metals because of the polymers’ complex-forming capabilities with metal ions. [18]

PAN has properties involving low density, thermal stability, high strength and modulus of elasticity. These unique properties have made PAN an essential polymer in high tech.

Its high tensile strength and tensile modulus are established by fiber sizing, coatings, production processes, and PAN's fiber chemistry. Its mechanical properties derived are important in composite structures for military and commercial aircraft. [19]

Carbon fiber

Polyacrylonitrile is used as the precursor for 90% of carbon fiber production. [20] Approximately 20–25% of Boeing and Airbus wide-body airframes are carbon fibers. However, applications are limited by PAN's high price of around $15/lb. [21]

Glassy carbon

Glassy carbon, a common electrode material in electrochemistry, is created by heat-treating blocks of polyacrylonitrile under pressure at 1000 to 3000 °C over a period of several days. The process removes non-carbon atoms and creates a conjugated double bond structure with excellent conductivity. [22]

Oxidized polyacrylonitrile fiber (OPF)

Oxidized PAN Fiber is used to produce inherently flame resistant (FR) fabrics.[ citation needed ] Commonly when it is used in FR fabrics for protective apparel it is referred to as OPF (oxidized polyacrylonitrile fiber) and is a high-performance, cost-effective flame and heat resistance solution. OPF can be considered one of the most FR fabrics commercially produced since it has an LOI (Limiting Oxygen Index) in the range of 45–55% which is one of the highest LOI ranges available as compared with other common FR fabrics which have lower LOI values (e.g. Nomex @ 28–30%, Kevlar @ 28–30%, Modacrylic @ 32–34%, PBI @ 41%, and FR-Viscose @ 28%);[ citation needed ] and OPF also demonstrates the lowest toxic gas generation upon burning as compared with other common fabrics (e.g. Nomex, FR Polyester, and Cotton).[ citation needed ]

Support polymer

Divinylbenzene-crosslinked polyacrylonitrile is a precursor to ion exchange resins. Hydrolysis converts the nitrile groups to carboxylic acids. Amberlite IRC86 is one commercial product. These weakly acidic resins have high affinities for divalent metal ions like Ca2+ and Mg2+. [23]

Related Research Articles

<span class="mw-page-title-main">Petrochemical</span> Chemical product derived from petroleum

Petrochemicals are the chemical products obtained from petroleum by refining. Some chemical compounds made from petroleum are also obtained from other fossil fuels, such as coal or natural gas, or renewable sources such as maize, palm fruit or sugar cane.

<span class="mw-page-title-main">Polyethylene</span> Most common thermoplastic polymer

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 bottles, etc.). As of 2017, over 100 million tonnes of polyethylene resins are being produced annually, accounting for 34% of the total plastics market.

<span class="mw-page-title-main">Carbon fibers</span> Material fibers about 5–10 μm in diameter composed of carbon

Carbon fibers or carbon fibres are fibers about 5 to 10 micrometers (0.00020–0.00039 in) in diameter and composed mostly of carbon atoms. Carbon fibers have several advantages: high stiffness, high tensile strength, high strength to weight ratio, high chemical resistance, high-temperature tolerance, and low thermal expansion. These properties have made carbon fiber very popular in aerospace, civil engineering, military, motorsports, and other competition sports. However, they are relatively expensive compared to similar fibers, such as glass fiber, basalt fibers, or plastic fibers.

<span class="mw-page-title-main">Acrylonitrile butadiene styrene</span> Thermoset polymer

Acrylonitrile butadiene styrene (ABS) (chemical formula (C8H8)x·​(C4H6)y·​(C3H3N)z ) is a common thermoplastic polymer. Its glass transition temperature is approximately 105 °C (221 °F). ABS is amorphous and therefore has no true melting point.

Acrylonitrile is an organic compound with the formula CH2CHCN and the structure H2C=CH−C≡N. It is a colorless, volatile liquid. It has a pungent odor of garlic or onions. Its molecular structure consists of a vinyl group linked to a nitrile. It is an important monomer for the manufacture of useful plastics such as polyacrylonitrile. It is reactive and toxic at low doses.

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, are not attacked by moths or mildew, and are nonallergenic. Among their uses are in apparel linings, furlike outerwear, paint-roller covers, scatter rugs, carpets, and work clothing and as hair in wigs.

<span class="mw-page-title-main">Acrylic fiber</span> Synthetic fiber made from polymer

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.

<span class="mw-page-title-main">Dynel</span>

Dynel is a trade name for a type of synthetic fiber used in fibre reinforced plastic composite materials, especially for marine applications. As it is easily dyed, it was also used to fabricate wigs. The fashion designer Pierre Cardin used Dynel fabric to make a collection of heat-molded dresses in 1968. A copolymer of acrylonitrile and vinyl chloride, Dynel shares many properties with both polyacrylonitrile and PVC. It is an acrylic resin.

In polymer chemistry, vinyl polymers are a group of polymers derived from substituted vinyl monomers. Their backbone is an extended alkane chain [−CH2−CHR−]. In popular usage, "vinyl" refers only to polyvinyl chloride (PVC).

<span class="mw-page-title-main">Acrylate polymer</span> Group of polymers prepared from acrylate monomers

An acrylate polymer is any of a group of polymers prepared from acrylate monomers. These plastics are noted for their transparency, resistance to breakage, and elasticity.

<span class="mw-page-title-main">Ethyl acrylate</span> Chemical compound

Ethyl acrylate is an organic compound with the formula CH2CHCO2CH2CH3. It is the ethyl ester of acrylic acid. It is a colourless liquid with a characteristic acrid odor. It is mainly produced for paints, textiles, and non-woven fibers. It is also a reagent in the synthesis of various pharmaceutical intermediates.

<span class="mw-page-title-main">Aksa (company)</span> Turkish company

Aksa is a Turkish company manufacturing carbon fiber, natural white and solution dyed acrylic staple fiber, tow and tops for yarn spinning and non-wovens. Established in 1968 in Yalova, Turkey, the company is the world's largest producer under one roof, with an annual production capacity of 308,000 tons.

<span class="mw-page-title-main">Methyl acrylate</span> Chemical compound

Methyl acrylate is an organic compound, more accurately the methyl ester of acrylic acid. It is a colourless liquid with a characteristic acrid odor. It is mainly produced to make acrylate fiber, which is used to weave synthetic carpets. It is also a reagent in the synthesis of various pharmaceutical intermediates. Owing to the tendency of methyl acrylate to polymerize, samples typically contain an inhibitor such as hydroquinone.

<span class="mw-page-title-main">Styrene-acrylonitrile resin</span> Chemical compound

Styrene acrylonitrile resin (SAN) is a copolymer plastic consisting of styrene and acrylonitrile. It is widely used in place of polystyrene owing to its greater thermal resistance. The chains of between 70 and 80% by weight styrene and 20 to 30% acrylonitrile. Larger acrylonitrile content improves mechanical properties and chemical resistance, but also adds a yellow tint to the normally transparent plastic.

In polymer chemistry, a comonomer refers to a polymerizable precursor to a copolymer aside from the principal monomer. In some cases, only small amounts of a comonomer are employed, in other cases substantial amounts of comonomers are used. Furthermore, in some cases, the comonomers are statistically incorporated within the polymer chain, whereas in other cases, they aggregate. The distribution of comonomers is referred to as the "blockiness" of a copolymer.

Spinning is a manufacturing process for creating polymer fibers. It is a specialized form of extrusion that uses a spinneret to form multiple continuous filaments.

<span class="mw-page-title-main">Paper chemicals</span> Chemicals used in paper manufacturing

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<span class="mw-page-title-main">Cyclohexanedimethanol</span> Chemical compound

Cyclohexanedimethanol (CHDM) is a mixture of isomeric organic compounds with formula C6H10(CH2OH)2. It is a colorless low-melting solid used in the production of polyester resins. Commercial samples consist of a mixture of cis and trans isomers. It is a di-substituted derivative of cyclohexane and is classified as a diol, meaning that it has two OH functional groups. Commercial CHDM typically has a cis/trans ratio of 30:70.

<span class="mw-page-title-main">2-Vinylpyridine</span> Chemical compound

2-Vinylpyridine is an organic compound with the formula CH2CHC5H4N. It is a derivative of pyridine with a vinyl group in the 2-position, next to the nitrogen. It is a colorless liquid, although samples are often brown. It is used industrially as a precursor to specialty polymers and as an intermediate in the chemical, pharmaceutical, dye, and photo industries. Vinylpyridine is sensitive to polymerization. It may be stabilized with a polymerisation inhibitor such as tert-butylcatechol. Owing to its tendency to polymerize, samples are typically refrigerated.

<span class="mw-page-title-main">Acrylonitrile styrene acrylate</span> Chemical compound

Acrylonitrile styrene acrylate (ASA), also called acrylic styrene acrylonitrile, is an amorphous thermoplastic developed as an alternative to acrylonitrile butadiene styrene (ABS), that has improved weather resistance. It is an acrylate rubber-modified styrene acrylonitrile copolymer. It is used for general prototyping in 3D printing, where its UV resistance and mechanical properties make it an excellent material for use in fused filament fabrication printers, particularly for outdoor applications. ASA is also widely used in the automotive industry.

References

  1. ↑ J Gordon Cook (1984). Handbook of Textile Fibres: Man-Made Fibres. Woodhead Publishing. p. 393. ISBN   9781855734852.
  2. 1 2 Nogaj, Alfred; Süling, Carlhans; Schweizer, Michael (2011). "Fibers, 8. Polyacrylonitrile Fibers". Ullmann's Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.o10_o04. ISBN   978-3527306732.
  3. ↑ H. Finkentscher, C. Heuck, DE Patent 654989, Verfahren zur Herstellung von Polymerisationprodukten, Anmeldetag 18.2.1930
  4. ↑ Walter Wetzel, Entdeckungsgeschichte der Polyfluorethylene - Zufall oder Ergebnis gezielter Forschung? N.T. M. 13 (2005) 79–91
  5. ↑ "KUNSTFASERN / INDUSTRIE : Das Salz der Mode - DER SPIEGEL 20/1955". www.spiegel.de.
  6. ↑ H. Rein, DE-Patent 631756, Verfahren zur Lösung von polymerem Acrylsäurenitril, Anmeldetag 8 August 1934
  7. ↑ Rein, Herbert (1948). "Polyacrylnitril-Fasern Eine neue Gruppe von synthethischen Fasern". Angewandte Chemie. 60 (6): 159–161. Bibcode:1948AngCh..60..159R. doi:10.1002/ange.19480600607.
  8. ↑ Bunsell, A.R. (18 January 2018). Handbook of properties of textile and technical fibres (2nd ed.). Woodhead Publishing. ISBN   9780081012727.
  9. ↑ C. H. Ray US Patent 2 404 713, Method for Preparing Polymeric Solutions, Filing date: 17.06.1942
  10. ↑ Herbert Bode Geschichte der Chemiefaser-industrie der Deutschen Demokratischen Republik. In: Mitteilungen, Gesellschaft Deutscher Chemiker / Fachgruppe Geschichte der Chemie (Frankfurt/Main), Bd. 14 (1998), S. 162. Retrieves 13 December 2021.
  11. ↑ Lothar Rudolph: Eigenschaften, Verspinnung und Einsatzmöglichkeiten von Wolcrylon. Mitteilung aus dem Zellwolle-Technikum der VEB Filmfabrik Agfa Wolfen. Wolfen 1954.
  12. ↑ Gupta, A. K.; Paliwal, D. K.; Bajaj, P. (1998). "Melting behavior of acrylonitrile polymers". Journal of Applied Polymer Science. 70 (13): 2703–2709. doi:10.1002/(sici)1097-4628(19981226)70:13<2703::aid-app15>3.3.co;2-u.
  13. ↑ Internet, D4W Comunicação - Soluções em. "IGTPAN". www.igtpan.com. Retrieved 2018-05-10.{{cite web}}: CS1 maint: numeric names: authors list (link)
  14. ↑ Guyot, Alain (1986). "16 - Precipitation Polymerization". Comprehensive Polymer Science and Supplements. Vol. 4. Pergamon. p. 261-273. doi:10.1016/B978-0-08-096701-1.00131-2. ISBN   978-0-08-096701-1.
  15. ↑ Kaur, Jasjeet; Millington, Keith; Smith, Shaun (2016-10-10). "Producing high-quality precursor polymer and fibers to achieve theoretical strength in carbon fibers: A review: REVIEW". Journal of Applied Polymer Science. 133 (38). doi:10.1002/app.43963. hdl: 10536/DRO/DU:30102165 .
  16. ↑ Serkov, A; Radishevskii, M (2008). "Status and Prospects For Production Of Carbon Fibres Based on Polyacrylonitrile". Fibre Chemistry. 40 (1): 24–31. doi:10.1007/s10692-008-9012-y. S2CID   137117495.
  17. ↑ Szostech, Michael. "Fiberglass in Mattresses" . Retrieved 11 August 2023.
  18. ↑ Delong, Liu (2011). "Synthesis of Polyacrylonitrile by Single-electron Transfer-living Radical Polymerization Using Fe(0) as Catalyst and Its Absorption Properties After Modification". Journal of Polymer Science Part A: Polymer Chemistry. 49 (13): 2916–2923. Bibcode:2011JPoSA..49.2916L. doi:10.1002/pola.24727.
  19. ↑ "Polyacrylonitrile (PAN) Carbon Fibers Industrial Capability Assessment" (PDF). United States of America Department of Defense. Archived from the original (PDF) on 4 March 2016. Retrieved 4 December 2013.
  20. ↑ "Top 9 Things You Didn't Know about Carbon Fiber | Department of Energy". Energy.gov. 2013-03-29. Retrieved 2013-12-08.
  21. ↑ John McElroy. "Manufacturing advances bring carbon fiber closer to mass production". Autoblog. Retrieved 2013-12-08.
  22. ↑ Handbook of Electrochemistry. Elsevier. 2021-07-02.
  23. ↑ De Dardel, François; Arden, Thomas V. (2008). "Ion Exchangers". Ullmann's Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.a14_393.pub2. ISBN   978-3527306732.
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