Kraton (polymer)

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Kraton is the trade name given to a number of high-performance elastomers manufactured by Kraton Polymers, and used as synthetic replacements for rubber. Kraton polymers offer many of the properties of natural rubber, such as flexibility, high traction, and sealing abilities, but with increased resistance to heat, weathering, and chemicals.

Contents

Company

The origin of Kraton polymers goes back to the synthetic rubber (GR-S) program funded by the U.S. government during World War II to develop and establish a domestic supply capability for synthetic styrene butadiene rubber (SBR) as an alternative to natural rubber. [1]

Shell Oil Company purchased the Torrance, California facility from the U.S. government that was built to make synthetic styrene butadiene rubber. [2] The company formed Elastomers Division that eventually became Kraton Corporation. Shell Oil Company broaden the product portfolio of elastomers in the 1950s, [3] under the technical leadership of Murray Luftglass and Norman R. Legge. [4]

As part of the divestment program that was announced by Shell in December 1998, the Kraton elastomers business was sold to a private equity firm Ripplewood Holdings in 2000. [5] [6] Kraton completed IPO on December 17, 2009 to became a separate publicly traded company. [7] In 2021 Kraton employees won an ASC Innovation Award for "Next Generation of Biobased Tackifiers REvolutionTM". [8] Kraton employees accept an ASC Innovation Award

Properties

Sbs block copolymer in TEM Sbs block copolymer.jpg
Sbs block copolymer in TEM

Kraton polymers are styrenic block copolymer (SBC) consisting of polystyrene blocks and rubber blocks. The rubber blocks consist of polybutadiene, polyisoprene, or their hydrogenated equivalents. The tri-block with polystyrene blocks at both extremities linked together by a rubber block is the most important polymer structure observed in SBC. If the rubber block consists of polybutadiene, the corresponding triblock structure is: poly(styrene-block-butadiene-block-styrene) usually abbreviated as SBS. Kraton D (SBS and SIS) and their selectively hydrogenated versions Kraton G (SEBS and SEPS) are the major Kraton polymer structures. The microstructure of SBS consists of domains of polystyrene arranged regularly in a matrix of polybutadiene, as shown in the TEM micrograph. The picture was obtained on a thin film of polymer cast onto mercury from solution, and then stained with osmium tetroxide.

The glass transition temperature (Tg) of the polybutadiene blocks is typically −90 °C and Tg of the polystyrene blocks is +100 °C. So, at any temperature between about −90 °C and +100 °C Kraton SBS will act as a physically crosslinked elastomer. If Kraton polymers are heated substantially above the Tg of the styrene-derived blocks, that is, above about 100 °C, like 170 °C the physical cross-links change from rigid glassy regions to flowable melt regions and the entire material flows and therefore can be cast, molded, or extruded into any desired form. On cooling, this new form resumes its elastomeric character. This is the reason such a material is called a thermoplastic elastomer (TPE). The polystyrene blocks form domains of nanometre size in the microstructure, and they stabilize the form of the molded material. Depending on the rubber-to-polystyrene ratio in the material, the polystyrene domains can be spherical or form cylinders or lamellae. The hydrogenated Kraton polymers named Kraton G exhibit improved resistance to temperature (processing at 200–230 °C is common), to oxidation, and to UV. SEBS and SEPS due to their polyolefinic rubber nature present excellent compatibility with polyolefins and paraffinic oils.

Applications

Flexible fascia between bumper and body on 1974-1978 AMC Matador sedans and station wagons 1974 AMC Matador sedan in Golden Tan standard interior at Rambler Ranch bumper.jpg
Flexible fascia between bumper and body on 1974-1978 AMC Matador sedans and station wagons
Color matched Kraton wheel opening extensions on 1980-1988 AMC Eagles 1982 AMC Eagle 4-door wagon two-tone 07.jpg
Color matched Kraton wheel opening extensions on 1980–1988 AMC Eagles

Kraton polymers are always used in blends with various other ingredients like paraffinic oils, polyolefins, polystyrene, bitumen, tackifying resins, and fillers to provide a very large range of end-use products ranging from hot melt adhesives to impact-modified transparent polypropylene bins, from medical TPE compounds to modified bitumen roofing felts or from oil gel toys (including sex toys) to elastic attachments in diapers. [9]

It can make asphalt flexible, which is necessary if the asphalt is to be used to coat a surface that is below grade or for highly demanding paving applications like F1 racing tracks. [10]

Kraton-based compounds are also used in non-slip knife handles. [11] [12]

The earliest commercial components using Kraton G (thermoplastic rubber) in the automobile industry were in 1970s. [13] The implementation of U.S. requirements for automobile bumpers to absorb 5 mph (8 km/h) impacts with no damage to the car's safety equipment lead to the first successful commercial automotive application of specialized flexible polymers as fascia for the 1974 AMC Matador. [14]

American Motors Corporation (AMC) also used this polymer plastic on the AMC Eagle for the color matched flexible wheel arch flares that flowed into rocker panel extensions. [15] [16] This was needed because of the Eagle's 2-inch wider track compared to the AMC Concord platform on which the AWD cars were based on. [17] The Eagle's Kraton bodywork was lightweight, flexible, and did not crack in cold weather as is typical of fiberglass automobile body components. [18]

Some grades of Kraton can also be dissolved into hydrocarbon oils to create "shear thinning" grease-type products that are used in the manufacture of telecommunications cables containing optical fibers.

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">Polystyrene</span> Polymer resin widely used in packaging

Polystyrene (PS) is a synthetic polymer made from monomers of the aromatic hydrocarbon styrene. Polystyrene can be solid or foamed. General-purpose polystyrene is clear, hard, and brittle. It is an inexpensive resin per unit weight. It is a poor barrier to oxygen and water vapor and has a relatively low melting point. Polystyrene is one of the most widely used plastics, with the scale of its production being several million tonnes per year. Polystyrene is naturally transparent, but can be colored with colorants. Uses include protective packaging, containers, lids, bottles, trays, tumblers, disposable cutlery, in the making of models, and as an alternative material for phonograph records.

<span class="mw-page-title-main">Thermoplastic</span> Plastic that softens with heat and hardens on cooling

A thermoplastic, or thermosoft plastic, is any plastic polymer material that becomes pliable or moldable at a certain elevated temperature and solidifies upon cooling.

<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.

<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">Copolymer</span> Polymer derived from more than one species of monomer

In polymer chemistry, a copolymer is a polymer derived from more than one species of monomer. The polymerization of monomers into copolymers is called copolymerization. Copolymers obtained from the copolymerization of two monomer species are sometimes called bipolymers. Those obtained from three and four monomers are called terpolymers and quaterpolymers, respectively. Copolymers can be characterized by a variety of techniques such as NMR spectroscopy and size-exclusion chromatography to determine the molecular size, weight, properties, and composition of the material.

<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. Their primary uses are for seals, adhesives and molded flexible parts.

<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.

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. They are more resistant to oxidizing agents, such as oxygen and ozone which can reduce the life of products like tires.

<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. Polybutadiene rubber is a polymer formed from the polymerization of the monomer 1,3-butadiene. Polybutadiene has a high resistance to wear and is used especially in the manufacture of tires, which consumes about 70% of the production. Another 25% is used as an additive to improve the toughness of plastics such as polystyrene and acrylonitrile butadiene styrene (ABS). Polybutadiene rubber accounted for about a quarter of total global consumption of synthetic rubbers in 2012. It is also used to manufacture golf balls, various elastic objects and to coat or encapsulate electronic assemblies, offering high electrical resistivity. 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.

A polyolefin is a type of polymer with the general formula (CH2CHR)n where R is an alkyl group. They are usually derived from a small set of simple olefins (alkenes). Dominant in a commercial sense are polyethylene and polypropylene. More specialized polyolefins include polyisobutylene and polymethylpentene. They are all colorless or white oils or solids. Many copolymers are known, such as polybutene, which derives from a mixture of different butene isomers. The name of each polyolefin indicates the olefin from which it is prepared; for example, polyethylene is derived from ethylene, and polymethylpentene is derived from 4-methyl-1-pentene. Polyolefins are not olefins themselves because the double bond of each olefin monomer is opened in order to form the polymer. Monomers having more than one double bond such as butadiene and isoprene yield polymers that contain double bonds (polybutadiene and polyisoprene) and are usually not considered polyolefins. Polyolefins are the foundations of many chemical industries.

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.

Thermoplastic elastomers (TPE), sometimes referred to as thermoplastic rubbers, are a class of copolymers or a physical mix of polymers that consist of materials with both thermoplastic and elastomeric properties. While most elastomers are thermosets, thermoplastics are in contrast relatively easy to use in manufacturing, for example, by injection moulding. Thermoplastic elastomers show advantages typical of both rubbery materials and plastic materials. The benefit of using thermoplastic elastomers is the ability to stretch to moderate elongations and return to its near original shape creating a longer life and better physical range than other materials. The principal difference between thermoset elastomers and thermoplastic elastomers is the type of cross-linking bond in their structures. In fact, crosslinking is a critical structural factor which imparts high elastic properties.

Thermoplastic olefin, thermoplastic polyolefin (TPO), or olefinic thermoplastic elastomers refer to polymer/filler blends usually consisting of some fraction of a thermoplastic, an elastomer or rubber, and usually a filler.

Membrane roofing is a type of roofing system for buildings, RV's, Ponds and in some cases tanks. It is used to create a watertight covering to protect the interior of a building. Membrane roofs are most commonly made from synthetic rubber, thermoplastic, or modified bitumen. Membrane roofs are most commonly used in commercial application, though they are becoming increasingly common in residential application.

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<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">Kumho Petrochemical</span> South Korean multinational chemical company

Kumho Petrochemical Co., Ltd. is a multinational chemical company based in South Korea, with headquarters in Seoul. It was founded in 1970 when Kumho Group struggled to secure raw materials for its bus and tire businesses. Kumho Petrochemical has a global market leadership in the manufacturing of synthetic rubbers with the world's largest production capacity based on SBR and BR by IISRP 2012. It focuses on synthetic rubbers, synthetic resins, specialty chemicals, electronic chemicals, energy, building materials and advanced materials as its core business.

<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), but with improved weather resistance, and is widely used in the automotive industry. 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 deposition modelling printers.

References

  1. ↑ "History 1940s". kraton.com. Retrieved 13 January 2023.
  2. ↑ "History 1950s". kraton.com. Retrieved 14 January 2023.
  3. ↑ "CEO's message". kraton.com. Archived from the original on 5 November 2012. Retrieved 13 January 2023.
  4. ↑ Hsieh, Henry; Quirk, Rodney (1996). Anionic Polymerization: Principles and Practical Applications. CRC Press. p. 480. ISBN   9780824795238 . Retrieved 19 August 2017.
  5. ↑ Bowden, Drew (7 September 2000). "Royal Dutch/Shell to sell Kraton elastomers to investors". chemicalonline.com. Retrieved 13 January 2023.
  6. ↑ Cousins, Keith (2001). Polymers for Electronic Components. Rapra Technology. p. 101. ISBN   9781847351982 . Retrieved 4 November 2012.
  7. ↑ "History 2010". kraton.com. Retrieved 13 January 2023.
  8. ↑ "Innovation Awards - Adhesive and Sealant Council". www.ascouncil.org. Retrieved 2023-08-09.
  9. ↑ "History 1980s". kraton.com. Retrieved 13 January 2023.
  10. ↑ Beskrovniy, D.; Davletbaeva, I.; Gumerova, O. (2022). Chemistry, Technology and Properties of Synthetic Rubber. Russia: Kazan National Research Technological University Publishing. p. 186. ISBN   9785040191444 . Retrieved 13 January 2023– via Google Books.
  11. ↑ "Commercial News USA: New Products and Trade Information". U.S. Department of Commerce, Industry and Trade Administration. 1985. p. 18. Retrieved 13 January 2023– via Google Books.
  12. ↑ Kertzman, Joe (8 September 2008). "Knives 2009". F+W Media. Retrieved 13 January 2023.
  13. ↑ Thermoplastic elastomers II: Processing for performance: Papers from a one-day seminar, Volume 2. iSmithers Rapra Technology. 1989. ISBN   9780902348417 . Retrieved 29 January 2017.
  14. ↑ "History 1970s". kraton.com. Retrieved 13 January 2023.
  15. ↑ Cranswick, Marc (2012). The Cars of American Motors: An Illustrated History . McFarland. p.  270. ISBN   9780786446728 . Retrieved 29 January 2017. A plastic polymer material bearing the trademark name "Kraton" was used for the wheel well extenders, rocker moldings and lower door panel protectors.
  16. ↑ "1981 American Motors Corporation Eagle (brochure) Eagle Standard Features" (PDF). xr793.com. p. 14. Retrieved 13 January 2023.
  17. ↑ "1986 AMC Eagle Wagon – Ahead Of Its Time, And Behind The Times". Curbside Classic. 25 October 2017. Retrieved 13 January 2023.
  18. ↑ Scott, Jordon (27 March 2020). "Junkyard Tour of the Jeep and Eagle 4WD Vehicles That Saved AMC". Motor Trend. Retrieved 13 January 2023.
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