Synthetic rubber

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A synthetic rubber is an artificial elastomer. They are polymers synthesized from petroleum byproducts. About 32 million metric tons of rubbers are produced annually in the United States, and of that amount two thirds are synthetic. Synthetic rubber, just like natural rubber, has many uses in the automotive industry for tires, door and window profiles, seals such as O-rings and gaskets, hoses, belts, matting, and flooring. They offer a different range of physical and chemical properties which can improve the reliability of a given product or application. Synthetic rubbers are superior to natural rubbers in two major respects: thermal stability, and resistance to oils and related compounds. [1] They are more resistant to oxidizing agents, such as oxygen and ozone which can reduce the life of products like tires.

Contents

History of synthetic rubber

John Boyd Dunlop (c. 1915) John Boyd Dunlop (c1915) (cropped).jpg
John Boyd Dunlop (c. 1915)

The expanded use of bicycles, and particularly their pneumatic tires, starting in the 1890s, created increased demand for rubber. In 1909, a team headed by Fritz Hofmann, working at the Bayer laboratory in Elberfeld, Germany, succeeded in polymerizing isoprene, making the first synthetic rubber. [2] [3]

Studies published in 1930 written independently by the Russian Sergey Lebedev, the American Wallace Carothers and the German scientist Hermann Staudinger led in 1931 to one of the first successful synthetic rubbers, known as neoprene, which was developed at DuPont under the direction of E. K. Bolton. Neoprene is highly resistant to heat and chemicals such as oil and gasoline, and is used in fuel hoses and as an insulating material in machinery. The company Thiokol applied their name to a competing type of rubber based on ethylene dichloride. [4]

In 1935, German chemists synthesized the first of a series of synthetic rubbers known as Buna rubbers. These were copolymers, meaning the polymers were made up from two monomers in alternating sequence. Other brands included Koroseal, which Waldo Semon developed in 1935, and Sovprene, which Soviet researchers created in 1940. [5]

World War II

Sheet of synthetic rubber coming off the rolling mill at the plant of Goodrich (1941) Sheet of synthetic rubber coming off the rolling mill at the plant of Goodrich.jpg
Sheet of synthetic rubber coming off the rolling mill at the plant of Goodrich (1941)
World War II poster about synthetic rubber tires "WATCH FOR THESE MARKS" - NARA - 516054.jpg
World War II poster about synthetic rubber tires

Production of synthetic rubber in the United States expanded greatly during World War II since the Axis powers controlled nearly all the world's limited supplies of natural rubber by mid-1942, following the Japanese conquest of most of Asia, particularly in the Southeast Asian colonies of British Malaya (now Malaysia) and the Dutch East Indies (now Indonesia) from where much of the global supply of natural rubber was sourced. [6]

Operation Pointblank bombing targets of Nazi Germany included the Schkopau (50,000 tons/yr) plant and the Hüls synthetic rubber plant near Recklinghausen (30,000, 17%), [7] and the Kölnische Gummifäden Fabrik tire and tube plant at Deutz on the east bank of the Rhine. [8] The Ferrara, Italy, synthetic rubber factory (near a river bridge) was bombed August 23, 1944. [9] Three other synthetic rubber facilities were at Ludwigshafen/Oppau (15,000), Hanover/Limmer (reclamation, 20,000), and Leverkusen (5,000). A synthetic rubber plant at Oświęcim, in Nazi-occupied Poland, was under construction on March 5, 1944 [10] operated by IG Farben and supplied with slave labor, by the SS, from the associated camp Auschwitz III (Monowitz). [11] [12]

Types

The most prevalent synthetic rubber is styrene-butadiene rubbers (SBR) derived from the copolymerization of styrene and 1,3-butadiene. Other synthetic rubbers include:

Many variations of these can be prepared with mixtures of monomers and with various catalysts that allow for control of stereochemistry. [13]

Polyisobutylene or butyl rubber is commonly used in tyre inner tubes or linings owing to its resistance to diffusion of air through the lining. It is a much less resilient material than cis-polybutadiene which is frequently used in tyre sidewalls to minimize energy losses and heat build-up. It is so resilient that it is used in super balls. An elastomer widely used for external sheet such as roof coverings is Hypalon or chlorosulphonated polyethylene. Synthetic rubbers like EPR can also be used for electrical insulation.

Silicone rubber

Silicone rubber is also a synthetic elastomer composed of silicone polymers. Silicone rubbers are widely used in industry, and there are multiple formulations. Silicone rubbers are often one- or two-part polymers, and may contain fillers to improve properties or reduce cost. Silicone rubber is generally non-reactive, stable, and resistant to extreme environments and temperatures.

Natural vs. synthetic rubber

Chemical structure of cis-polyisoprene, the main constituent of natural rubber. Synthetic cis-polyisoprene and natural cis-polyisoprene are derived from different precursors by different chemical pathways. RubberSyn&Natural.png
Chemical structure of cis-polyisoprene, the main constituent of natural rubber. Synthetic cis-polyisoprene and natural cis-polyisoprene are derived from different precursors by different chemical pathways.

Natural rubber, coming from latex of Hevea brasiliensis , is mainly poly-cis-isoprene.

Synthetic rubber, like other polymers, is made from various petroleum-based monomers.

Some synthetic rubbers are less sensitive to ozone cracking than natural rubber. Natural rubber is sensitive owing to the double bonds in its chain structure, but some synthetic rubbers do not possess these bonds and so are more resistant to ozone cracking. Examples include Viton rubber, EPDM and butyl rubber.

A new class of synthetic rubber is the thermoplastic elastomers which can be moulded easily unlike conventional natural rubber vulcanized rubber. Their structure is stabilized by cross-linking by crystallites in the case of polyurethanes or by amorphous domains in the case of SBS block copolymers.

Related Research Articles

A monomer is a molecule that can react together with other monomer molecules to form a larger polymer chain or three-dimensional network in a process called polymerization.

<span class="mw-page-title-main">Vulcanization</span> Process of hardening rubber

Vulcanization is a range of processes for hardening rubbers. The term originally referred exclusively to the treatment of natural rubber with sulfur, which remains the most common practice. It has also grown to include the hardening of other (synthetic) rubbers via various means. Examples include silicone rubber via room temperature vulcanizing and chloroprene rubber (neoprene) using metal oxides.

<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">Butadiene</span> Chemical compound

1,3-Butadiene is the organic compound with the formula CH2=CH-CH=CH2. It is a colorless gas that is easily condensed to a liquid. It is important industrially as a precursor to synthetic rubber. The molecule can be viewed as the union of two vinyl groups. It is the simplest conjugated diene.

<span class="mw-page-title-main">Styrene-butadiene</span> Synthetic rubber polymer

Styrene-butadiene or styrene-butadiene rubber (SBR) describe families of synthetic rubbers derived from styrene and butadiene. These materials have good abrasion resistance and good aging stability when protected by additives. In 2012, more than 5.4 million tonnes of SBR were processed worldwide. About 50% of car tires are made from various types of SBR. The styrene/butadiene ratio influences the properties of the polymer: with high styrene content, the rubbers are harder and less rubbery. SBR is not to be confused with the thermoplastic elastomer, styrene-butadiene block copolymer, although being derived from the same monomers.

<span class="mw-page-title-main">Elastomer</span> Polymer with rubber-like elastic properties

An elastomer is a polymer with viscoelasticity and with weak intermolecular forces, generally low Young's modulus (E) and high failure strain compared with other materials. The term, a portmanteau of elastic polymer, is often used interchangeably with rubber, although the latter is preferred when referring to vulcanisates. Each of the monomers which link to form the polymer is usually a compound of several elements among carbon, hydrogen, oxygen and silicon. Elastomers are amorphous polymers maintained above their glass transition temperature, so that considerable molecular reconformation is feasible without breaking of covalent bonds. At ambient temperatures, such rubbers are thus relatively compliant and deformable.

<span class="mw-page-title-main">O-ring</span> Mechanical, toroid gasket that seals an interface

An O-ring, also known as a packing or a toric joint, is a mechanical gasket in the shape of a torus; it is a loop of elastomer with a round cross-section, designed to be seated in a groove and compressed during assembly between two or more parts, forming a seal at the interface.

<span class="mw-page-title-main">EPDM rubber</span> Type of synthetic rubber

EPDM rubber is a type of synthetic rubber that is used in many applications.

<span class="mw-page-title-main">Butyl rubber</span> Synthetic rubber; a copolymer of isobutylene with isoprene

Butyl rubber, sometimes just called "butyl", is a synthetic rubber, a copolymer of isobutylene with isoprene. The abbreviation IIR stands for isobutylene isoprene rubber. Polyisobutylene, also known as "PIB" or polyisobutene, (C4H8)n, is the homopolymer of isobutylene, or 2-methyl-1-propene, on which butyl rubber is based. Butyl rubber is produced by polymerization of about 98% of isobutylene with about 2% of isoprene. Structurally, polyisobutylene resembles polypropylene, but has two methyl groups substituted on every other carbon atom, rather than one. Polyisobutylene is a colorless to light yellow viscoelastic material. It is generally odorless and tasteless, though it may exhibit a slight characteristic odor.

<span class="mw-page-title-main">Polybutadiene</span> Type of synthetic rubber formed from the polymerization of butadiene

Polybutadiene [butadiene rubber, BR] is a synthetic rubber. It offers high elasticity, high resistance to wear, good strength even without fillers, and excellent abrasion resistance when filled and vulcanized. "Polybutadiene" is a collective name for homopolymers formed from the polymerization of the monomer 1,3-butadiene. The IUPAC refers to polybutadiene as "poly(buta-1,3-diene)". Historically, an early generation of synthetic polybutadiene rubber produced in Germany by Bayer using sodium as a catalyst was known as "Buna rubber". Polybutadiene is typically crosslinked with sulphur, however, it has also been shown that it can be UV cured when bis-benzophenone additives are incorporated into the formulation.

Nitrile rubber, also known as nitrile butadiene rubber, NBR, Buna-N, and acrylonitrile butadiene rubber, is a synthetic rubber derived from acrylonitrile (ACN) and butadiene. Trade names include Perbunan, Nipol, Krynac and Europrene. This rubber is unusual in being resistant to oil, fuel, and other chemicals.

<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.

Solution polymerization is a method of industrial polymerization. In this procedure, a monomer is dissolved in a non-reactive solvent that contains a catalyst or initiator.

<span class="mw-page-title-main">Ozone cracking</span> Cracks in many different elastomers due to ozone attack

Cracks can be formed in many different elastomers by ozone attack, and the characteristic form of attack of vulnerable rubbers is known as ozone cracking. The problem was formerly very common, especially in tires, but is now rarely seen in those products owing to preventive measures.

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.

<span class="mw-page-title-main">Antiozonant</span> Class of chemical compounds

An antiozonant, also known as anti-ozonant, is an organic compound that prevents or retards damage caused by ozone. The most important antiozonants are those which prevent degradation of elastomers like rubber. A number of research projects study the application of another type of antiozonants to protect plants as well as salmonids that are affected by the chemicals.

<span class="mw-page-title-main">Charles Goodyear Medal</span> Award

The Charles Goodyear Medal is the highest honor conferred by the American Chemical Society, Rubber Division. Established in 1941, the award is named after Charles Goodyear, the discoverer of vulcanization, and consists of a gold medal, a framed certificate and prize money. The medal honors individuals for "outstanding invention, innovation, or development which has resulted in a significant change or contribution to the nature of the rubber industry". Awardees give a lecture at an ACS Rubber Division meeting, and publish a review of their work in the society's scientific journal Rubber Chemistry and Technology.

<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.

Walter Bock was a German chemist who developed styrene-butadiene copolymer by emulsion polymerization as a synthetic rubber (SBR).

<span class="mw-page-title-main">Poly(butyl acrylate)</span> Chemical compound

Poly(butyl acrylate) (PBA) is a family of organic polymers with the formula (CH2CHCO2CH2CH2CH2CH3)n. It is a synthetic acrylate polymer derived from butyl acrylate monomer. The polymers are colorless. This homopolymer is far less important than copolymers derived from methyl acrylate and other monomers. It has a low glass-transition temperature of about -43 °C (20 °C).

References

  1. ↑ Threadingham, Desmond; Obrecht, Werner; Wieder, Wolfgang (2011). Ullmann's Encyclopedia of Industrial Chemistry . Weinheim: Wiley-VCH. doi:10.1002/14356007.a23_239.pub5. ISBN   978-3527306732.
  2. ↑ The Moving Powers of Rubber, Leverkusen, Germany: LANXESS AG: 20
  3. ↑ Michalovic, Mark (2000). "Destination Germany: A Poor Substitute". The Story of Rubber.
  4. ↑ Edwards, Douglas C. (2001). "Chap. 5 – Liquid Rubber". In Bhowmick, Anil K.; Stephens, Howard (eds.). Handbook of Elastomers, Second Edition (First ed.). Marcel Dekker Inc. p. 135. ISBN   0-8247-0383-9 . Retrieved 8 February 2015.
  5. ↑ Current Biography 1940, "SEMON, WALDO LONSBURY" pp. 723–724
  6. ↑ Gropman, Alan L. (1996). Mobilizing U. S. Industry in World War II. Institute for National Strategic Studies. p. 115. ISBN   0788136461.
  7. ↑ Stormont, John W. (March 1946) [summer of 1945], AAFRH-19: The Combined Bomber Offensive; April through December 1943, Dwight D. Eisenhower Presidential Library: Collection of 20th Century Military Records, 1918–1950 Series I: Historical Studies Box 35: AAF Historical Office; Headquarters, Army Air Force, pp. 74–5, 81, SECRET ... Classification Cancelled ... JUN 10 1959{{citation}}: CS1 maint: location (link)
  8. ↑ Gurney, Gene (1962), The War in the Air: a pictorial history of World War II Air Forces in combat, New York: Bonanza Books, p. 215
  9. ↑ "Army Air Forces in World War II". February 11, 2009. Archived from the original on 11 February 2009.
  10. ↑ Williamson, Charles C. (5 March 1944), Plan for Completion of Combined Bomber Offensive (Appendices C & F), Hughes, R. D.; Cabell, C. P.;Nazarro, J. J.; Bender, F. P.; & Crigglesworth, W. J., Dwight D. Eisenhower Presidential Library: SMITH, WALTER BEDELL: Collection of World War II Documents, 1941–1945; Box No.: 48: HQ, U.S.S.T.A.F, DECLASSIFIED ... 4/24/74{{citation}}: CS1 maint: location (link)
  11. ↑ Steinbacher, Sybille (2005). Auschwitz: a history . Translated by Whiteside, Shaun (1st Ecco ed.). New York: Ecco. p. 45. ISBN   978-0060825812.
  12. ↑ Herbert, Vernon; Bisio, Attilio (December 11, 1985). Synthetic Rubber: A Project That Had to Succeed. Contributions in Economics and Economic History. Greenwood Press. p. 32ff. ISBN   978-0313246340.
  13. ↑ Greve, Heinz-Hermann; Threadingham, Desmond (2000). "Rubber, 1. Survey". Ullmann's Encyclopedia of Industrial Chemistry . Weinheim: Wiley-VCH. doi:10.1002/14356007.a23_221. ISBN   3527306730.
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