Neoprene

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Neoprene
Diving suit neoprene.jpg
A neck seal, wrist seal, manual vent, inflator, zip and fabric of a neoprene dry suit. The soft seal material at the neck and wrists is made from single backed closed-cell foam neoprene for elasticity. The slick unbacked side seals against the skin. The blue area is double-backed with knit nylon fabric laminated onto closed cell foamed neoprene for toughness. Some insulation is provided by the suit, and the rest by garments worn underneath.
Polychloroprene.png
Chemical structure of the repeating unit of polychloroprene
Identifiers
ECHA InfoCard 100.127.980 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 618-463-8
Properties
Density 1.23 g/cm3 (solid)
0.1-0.3 g/cm3 (foam)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Neoprene (also polychloroprene) is a family of synthetic rubbers that are produced by polymerization of chloroprene. [1] Neoprene exhibits good chemical stability and maintains flexibility over a wide temperature range. Neoprene is sold either as solid rubber or in latex form and is used in a wide variety of commercial applications, such as laptop sleeves, orthopaedic braces (wrist, knee, etc.), electrical insulation, medical gloves, liquid and sheet-applied elastomeric membranes or flashings, and automotive fan belts. [2]

Contents

Production

Neoprene is produced by free-radical polymerization of chloroprene. In commercial production, this polymer is prepared by free radical emulsion polymerization. Polymerization is initiated using potassium persulfate. Bifunctional nucleophiles, metal oxides (e.g. zinc oxide), and thioureas are used to crosslink individual polymer strands. [3]

History

Neoprene was invented by DuPont scientists on April 17, 1930, after Elmer K. Bolton of DuPont attended a lecture by Fr Julius Arthur Nieuwland, a professor of chemistry at the University of Notre Dame. Nieuwland's research was focused on acetylene chemistry and during the course of his work he produced divinyl acetylene, a jelly that firms into an elastic compound similar to rubber when passed over sulfur dichloride. After DuPont purchased the patent rights from the university, Wallace Carothers of DuPont took over commercial development of Nieuwland's discovery in collaboration with Nieuwland himself and DuPont chemists Arnold Collins, Ira Williams and James Kirby. [4] Collins focused on monovinyl acetylene and allowed it to react with hydrogen chloride gas, manufacturing chloroprene. [5]

DuPont first marketed the compound in 1931 under the trade name DuPrene, [6] but its commercial possibilities were limited by the original manufacturing process, which left the product with a foul odor. [7] A new process was developed, which eliminated the odor-causing byproducts and halved production costs, and the company began selling the material to manufacturers of finished end-products. [7] To prevent shoddy manufacturers from harming the product's reputation, the trademark DuPrene was restricted to apply only to the material sold by DuPont. [7] Since the company itself did not manufacture any DuPrene-containing end products, the trademark was dropped in 1937 and replaced with a generic name, neoprene, in an attempt "to signify that the material is an ingredient, not a finished consumer product". [8] DuPont then worked extensively to generate demand for its product, implementing a marketing strategy that included publishing its own technical journal, which extensively publicized neoprene's uses as well as advertising other companies' neoprene-based products. [7] By 1939, sales of neoprene were generating profits over $300,000 for the company (equivalent to $6,600,000in 2023). [7]

Mechanical Properties

The high tensile performance of neoprene is a result of its highly regular backbone structure, which causes neoprene to undergo strain crystallization under tensile loading. [9] A two parameter (strain rate and temperature) hyperelastic model can accurately capture much of the mechanical response of neoprene. [10]

Exposure to acetone and heat have been shown to degrade the tensile strength and ultimate elongation of neoprene, likely due to a loss of plasticizers as well as an increase in crosslinking during heat exposure. [11] The response of neoprene to thermal aging depends not just on the highest temperature it is exposed to, but also on the exact temperature-time profile; this is a result of the competing factors of scission of the main polymer chain and oxidative cross-linking. [12] Chain scission leads to degradation, embrittlement, and a loss of toughness. [13] Oxidation reactions in the presence of heating leads to increased cross-linking, which in turn causes hardening. [12] The interplay of both these factors determines the resulting effect on material mechanical properties; cross-linking is thought to dominate for neoprene. [12] [14]

As neoprene is used to make electric cable jackets in nuclear power plants, the effect of gamma radiation on the mechanical properties of neoprene has also been investigated. Chain scission, possibly triggered by free radicals from irradiated oxygen, is seen to deteriorate the mechanical properties of neoprene. [15] Likewise, the tensile strength, hardness, and ultimate elongation of neoprene can also be degraded upon exposure to microwave radiation, which is of interest in the devulcanization process [16] Finally, ultraviolet radiation is seen to decrease the mechanical properties of neoprene, which is important for outdoors applications of neoprene. [17]

Mechanical Properties of Neoprene
PropertyValue
Ultimate tensile strength4000 PSI [9]
Young's modulus890 PSI [18]
Ultimate elongation600% [9]
Hardness (Durometer)30–95 [9]
Glass transition temperature -43°C [9]
Storage modulus (measured at 1 Hz)7.83 MPa [19]
Loss modulus (measured at 1 Hz)8.23 MPa [19]

Applications

General

Two styles of well-worn Xtratuf boots made with neoprene Xtra tufs.jpg
Two styles of well-worn Xtratuf boots made with neoprene

Neoprene resists degradation more than natural or synthetic rubber. This relative inertness makes neoprene well suited for demanding applications such as gaskets, hoses, and corrosion-resistant coatings. [1] It can be used as a base for adhesives, noise isolation in power transformer installations, and as padding in external metal cases to protect the contents while allowing a snug fit. It resists burning better than exclusively hydrocarbon based rubbers, [20] resulting in its appearance in weather stripping for fire doors and in combat related attire such as gloves and face masks. Because of its tolerance of extreme conditions, neoprene is used to line landfills. Neoprene's burn point is around 260 °C (500 °F). [21]

In its native state, neoprene is a very pliable rubber-like material with insulating properties similar to rubber or other solid plastics.

Neoprene foam is used in many applications and is produced in either closed-cell or open-cell form. The closed-cell form is waterproof, less compressible and more expensive. The open-cell form can be breathable. It is manufactured by foaming the rubber with nitrogen gas, where the tiny enclosed and separated gas bubbles can also serve as insulation. Nitrogen gas is most commonly used for the foaming of neoprene foam due to its inertness, flame resistance, and large range of processing temperatures. [22]

Civil engineering

Neoprene is used as a component of elastomeric bridge bearings, to support heavy loads while permitting small horizontal movements. [23]

Aquatics

Neoprene is a popular material in making protective clothing for aquatic activities. Foamed neoprene is commonly used to make fly fishing waders, wetsuits, and drysuits as it provides excellent insulation against cold. The foam is quite buoyant, and divers compensate for this by wearing weights. [24] Since foam neoprene contains gas pockets, the material compresses under water pressure, getting thinner at greater depths; a 7 mm neoprene wet suit offers much less exposure protection under 100 feet of water than at the surface. A recent advance in neoprene for wet suits is the "super-flex" variety, which uses spandex in the knit liner fabric for greater flexibility and stretch. [25] [26] A drysuit is similar to a wetsuit, but uses thicker and more durable neoprene to create an entirely waterproof suit that is suitable for wear in extremely cold water or polluted water.[ citation needed ]

Home accessories

Recently, neoprene has become a favorite material for lifestyle and other home accessories including laptop sleeves, tablet holders, remote controls, mouse pads, and cycling chamois.

Music

The Rhodes piano used hammer tips made of neoprene in its electric pianos, after changing from felt hammers around 1970. [27]

Neoprene is also used for speaker cones and drum practice pads. [28]

Hydroponic gardening

Hydroponic and aerated gardening systems make use of small neoprene inserts to hold plants in place while propagating cuttings or using net cups. Inserts are relatively small, ranging in size from 1.5 to 5 inches (4 to 13 cm). Neoprene is a good choice for supporting plants because of its flexibility and softness, allowing plants to be held securely in place without the chance of causing damage to the stem. Neoprene root covers also help block out light from entering the rooting chamber of hydroponic systems, allowing for better root growth and helping to deter the growth of algae.[ citation needed ]

Face mask

During the COVID-19 global pandemic, neoprene was identified by some health experts as an effective material to use for home made face masks. [29] Some commercial face mask manufacturers that use Neoprene have claimed 99.9% filtration for particles as small as 0.1 microns. [30] The size of coronavirus is identified to be on average 0.125 microns. [31]

Other

A woman wearing neoprene leggings Neoprene pants.jpg
A woman wearing neoprene leggings

Neoprene is used for Halloween masks and masks used for face protection, to make waterproof automotive seat covers, in liquid and sheet-applied elastomeric roof membranes or flashings, and in a neoprene-spandex mixture for manufacture of wheelchair positioning harnesses.

In tabletop wargames, neoprene mats printed with grassy, sandy, icy, or other natural features have become popular gaming surfaces. They are durable, firm and stable, and attractive in appearance, and also favoured for their ability to roll up in storage but lie flat when unrolled.

Because of its chemical resistance and overall durability, neoprene is sometimes used in the manufacture of dishwashing gloves, especially as an alternative to latex.

In fashion, neoprene has been used by designers such as Gareth Pugh, Balenciaga, Rick Owens, Lanvin, and Vera Wang.

Precautions

Some people are allergic to neoprene while others can get dermatitis from thiourea residues left from its production.[ clarification needed ]

The most common accelerator in the vulcanization of polychloroprene is ethylene thiourea (ETU), which has been classified as a reproductive toxin. From 2010 to 2013, the European rubber industry had a research project titled SafeRubber to develop a safer alternative to the use of ETU. [32]

See also

Related Research Articles

<span class="mw-page-title-main">Polymer</span> Substance composed of macromolecules with repeating structural units

A polymer is a substance or material consisting of very large molecules called macromolecules, composed of many repeating subunits. Due to their broad spectrum of properties, both synthetic and natural polymers play essential and ubiquitous roles in everyday life. Polymers range from familiar synthetic plastics such as polystyrene to natural biopolymers such as DNA and proteins that are fundamental to biological structure and function. Polymers, both natural and synthetic, are created via polymerization of many small molecules, known as monomers. Their consequently large molecular mass, relative to small molecule compounds, produces unique physical properties including toughness, high elasticity, viscoelasticity, and a tendency to form amorphous and semicrystalline structures rather than crystals.

<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">Wallace Carothers</span> Early 20th-century American chemist and inventor

Wallace Hume Carothers was an American chemist, inventor, and the leader of organic chemistry at DuPont, who was credited with the invention of nylon.

<span class="mw-page-title-main">Polymer degradation</span> Alteration in the polymer properties under the influence of environmental factors

Polymer degradation is the reduction in the physical properties of a polymer, such as strength, caused by changes in its chemical composition. Polymers and particularly plastics are subject to degradation at all stages of their product life cycle, including during their initial processing, use, disposal into the environment and recycling. The rate of this degradation varies significantly; biodegradation can take decades, whereas some industrial processes can completely decompose a polymer in hours.

<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">Chloroprene</span> Chemical compound

Chloroprene (IUPAC name 2-chlorobuta-1,3-diene) is a chemical compound with the molecular formula CH2=CCl−CH=CH2. Chloroprene is a colorless volatile liquid, almost exclusively used as a monomer for the production of the polymer polychloroprene, better known as neoprene, a type of synthetic rubber.

Elmer Keiser Bolton was an American chemist and research director for DuPont, notable for his role in developing neoprene and directing the research that led to the discovery of nylon.

<span class="mw-page-title-main">Julius Nieuwland</span> Belgian-born Holy Cross priest and professor of chemistry and botany

Julius Aloysius Arthur Nieuwland, CSC, was a Belgian-born Holy Cross priest and professor of chemistry and botany at the University of Notre Dame, Indiana. He is known for his contributions to acetylene research and its use as the basis for one type of synthetic rubber, which eventually led to the invention of neoprene by DuPont.

<span class="mw-page-title-main">Embrittlement</span> Loss of ductility of a material, making it brittle

Embrittlement is a significant decrease of ductility of a material, which makes the material brittle. Embrittlement is used to describe any phenomena where the environment compromises a stressed material's mechanical performance, such as temperature or environmental composition. This is oftentimes undesirable as brittle fracture occurs quicker and can much more easily propagate than ductile fracture, leading to complete failure of the equipment. Various materials have different mechanisms of embrittlement, therefore it can manifest in a variety of ways, from slow crack growth to a reduction of tensile ductility and toughness.

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

Foam latex or latex foam rubber is a lightweight form of latex containing bubbles known as cells, created from liquid latex. The foam is generally created though the Dunlop or Talalay process in which a liquid latex is foamed and then cured in a mold to extract the foam.

A blowing agent is a substance which is capable of producing a cellular structure via a foaming process in a variety of materials that undergo hardening or phase transition, such as polymers, plastics, and metals. They are typically applied when the blown material is in a liquid stage. The cellular structure in a matrix reduces density, increasing thermal and acoustic insulation, while increasing relative stiffness of the original polymer.

<span class="mw-page-title-main">Filler (materials)</span> Particles added to improve its properties

Filler materials are particles added to resin or binders that can improve specific properties, make the product cheaper, or a mixture of both. The two largest segments for filler material use is elastomers and plastics. Worldwide, more than 53 million tons of fillers are used every year in application areas such as paper, plastics, rubber, paints, coatings, adhesives, and sealants. As such, fillers, produced by more than 700 companies, rank among the world's major raw materials and are contained in a variety of goods for daily consumer needs. The top filler materials used are ground calcium carbonate (GCC), precipitated calcium carbonate (PCC), kaolin, talc, and carbon black. Filler materials can affect the tensile strength, toughness, heat resistance, color, clarity, etc. A good example of this is the addition of talc to polypropylene. Most of the filler materials used in plastics are mineral or glass based filler materials. Particulates and fibers are the main subgroups of filler materials. Particulates are small particles of filler that are mixed in the matrix where size and aspect ratio are important. Fibers are small circular strands that can be very long and have very high aspect ratios.

Polymer engineering is generally an engineering field that designs, analyses, and modifies polymer materials. Polymer engineering covers aspects of the petrochemical industry, polymerization, structure and characterization of polymers, properties of polymers, compounding and processing of polymers and description of major polymers, structure property relations and applications.

Electron-beam processing or electron irradiation (EBI) is a process that involves using electrons, usually of high energy, to treat an object for a variety of purposes. This may take place under elevated temperatures and nitrogen atmosphere. Possible uses for electron irradiation include sterilization, alteration of gemstone colors, and cross-linking of polymers.

<span class="mw-page-title-main">Photo-oxidation of polymers</span>

In polymer chemistry photo-oxidation is the degradation of a polymer surface due to the combined action of light and oxygen. It is the most significant factor in the weathering of plastics. Photo-oxidation causes the polymer chains to break, resulting in the material becoming increasingly brittle. This leads to mechanical failure and, at an advanced stage, the formation of microplastics. In textiles the process is called phototendering.

A thermoset polymer matrix is a synthetic polymer reinforcement where polymers act as binder or matrix to secure in place incorporated particulates, fibres or other reinforcements. They were first developed for structural applications, such as glass-reinforced plastic radar domes on aircraft and graphite-epoxy payload bay doors on the Space Shuttle.

Ira Williams (1894–1977) was an American chemist at DuPont's Jackson Laboratory in New Jersey, who in the summer of 1930, together with Wallace Carothers, Arnold Collins and F. B. Downing, made commercial Neoprene possible by producing a soft, plastic form of chloroprene that could be processed by the rubber industry. Early accounts of the development credited Julius Nieuwland with synthesizing the precursor divinylacetylene. Williams' contribution was the discovery that the rheological behavior of the product could be controlled by quenching the polymerization reaction with alcohol.

Gérard Berchet was a French-American chemist who played a pivotal role in the invention of both nylon and neoprene. Berchet worked under the direction of Wallace Carothers at DuPont Experimental Station and first synthesized nylon 6 on February 28, 1935, from equal parts hexamethylenediamine and adipic acid. Berchet was the first to synthesize neoprene. However, Arthur Collins is credited with its discovery on April 17, 1930, after he accidentally reacted hydrochloric acid with vinylacetylene. Berchet's leaving of his sample unexamined on a laboratory bench until after Collin's discovery prevented him from being credited with its discovery.

Arnold Miller Collins (1899-1982) was a chemist at DuPont who, working under Elmer Bolton and Wallace Carothers with Ira Williams, first isolated polychloroprene and 2-chloro-1, 3-butadiene in 1930.

References

  1. 1 2 Werner Obrecht, Jean-Pierre Lambert, Michael Happ, Christiane Oppenheimer-Stix, John Dunn and Ralf Krüger "Rubber, 4. Emulsion Rubbers" in Ullmann's Encyclopedia of Industrial Chemistry, 2012, Wiley-VCH, Weinheim. doi : 10.1002/14356007.o23_o01
  2. ↑ "Technical information — Neoprene" (PDF). Du Pont Performance Elastomers. October 2003. Archived from the original (PDF) on 2008-08-29. Retrieved 2008-02-06.
  3. ↑ Furman, Glenn E. (14 October 2005). "Chloroprene Polymers". Encyclopedia of Polymer Science and Technology. Wiley Online Library. doi:10.1002/0471440264.pst053. ISBN   0471440264.
  4. ↑ Carothers, Wallace H.; Williams, Ira.; Collins, Arnold M.; Kirby, James E. (November 1931). "Acetylene Polymers and Their Derivatives. Ii. A New Synthetic Rubber: Chloroprene and ITS Polymers". Journal of the American Chemical Society. 53 (11): 4203–4225. doi:10.1021/ja01362a042.
  5. ↑ Smith, John K. (January 1985). "The Ten-Year Invention: Neoprene and Du Pont Research, 1930-1939". Technology and Culture. 26 (1): 34–55. doi:10.2307/3104528. JSTOR   3104528. S2CID   113234844.
  6. ↑ "Neoprene: 1930 - Overview". DuPont Heritage. DuPont. Archived from the original on 9 March 2012. Retrieved 29 March 2011.
  7. 1 2 3 4 5 Hounshell, David A.; Smith, John Kenly (1988). Science and Corporate Strategy: Du Pont R&D, 1902-1980 (Repr. ed.). Cambridge [Cambridgeshire]: Cambridge University Press. pp.  253–257. ISBN   0-521-32767-9.
  8. ↑ "Neoprene: 1930 - In Depth". DuPont Heritage. DuPont. Archived from the original on 10 May 2011. Retrieved 29 March 2011.
  9. 1 2 3 4 5 Harris, Cyril M.; Piersol, Allan G., eds. (2002). Harris' shock and vibration handbook. McGraw-Hill handbooks (5th ed.). New York: McGraw-Hill. pp. Ch. 33. ISBN   978-0-07-137081-3.
  10. ↑ Trivedi, A. R.; Siviour, C. R. (2020-09-01). "A Simple Rate–Temperature Dependent Hyperelastic Model Applied to Neoprene Rubber". Journal of Dynamic Behavior of Materials. 6 (3): 336–347. doi:10.1007/s40870-020-00252-w. ISSN   2199-7454.
  11. ↑ Gao, Pengfei; Tomasovic, Beth (November 2005). "Change in Tensile Properties of Neoprene and Nitrile Gloves After Repeated Exposures to Acetone and Thermal Decontamination". Journal of Occupational and Environmental Hygiene. 2 (11): 543–552. doi:10.1080/15459620500315964. ISSN   1545-9624.
  12. 1 2 3 Alazhary, Sharif; Shaafaey, Mamoon; Bahrololoumi, Amir; Dargazany, Roozbeh (2024-03-18). "Investigating the effects of sequential aging temperature profiles on the response of neoprene rubber". Journal of Polymer Research. 31 (4): 102. doi:10.1007/s10965-024-03910-y. ISSN   1572-8935.
  13. ↑ Fayolle, Bruno; Richaud, Emmanuel; Colin, Xavier; Verdu, Jacques (2008). "Review: degradation-induced embrittlement in semi-crystalline polymers having their amorphous phase in rubbery state". Journal of Materials Science. 43 (22): 6999–7012. doi:10.1007/s10853-008-3005-3. ISSN   0022-2461.
  14. ↑ Ito, Masayuki; Okada, Sohei; Kuriyama, Isamu (1981-01-01). "The deterioration of mechanical properties of chloroprene rubber in various conditions". Journal of Materials Science. 16 (1): 10–16. doi:10.1007/BF00552053. ISSN   1573-4803.
  15. ↑ Ito, Masayuki; Okada, Sohei; Kuriyama, Isamu (1981-01-01). "The deterioration of mechanical properties of chloroprene rubber in various conditions". Journal of Materials Science. 16 (1): 10–16. doi:10.1007/BF00552053. ISSN   1573-4803.
  16. ↑ Scagliusi, Sandra; Araújo, Sumair G.; Landini, Liliane; Lugão, Ademar B. (2009). "STUDY OF PROPERTIES OF CHLOROPRENE RUBBER DEVULCANIZATE BY RADIATION IN MICROWAVE" (PDF). 2009 International Nuclear Atlantic Conference.
  17. ↑ Chou, Hsoung‐Wei; Huang, Jong‐Shin (2008-12-05). "Effects of ultraviolet irradiation on the static and dynamic properties of neoprene rubbers". Journal of Applied Polymer Science. 110 (5): 2907–2913. doi:10.1002/app.28903. ISSN   0021-8995.
  18. ↑ "MatWeb - The Online Materials Information Resource". www.matweb.com. Retrieved 2024-05-13.
  19. 1 2 Luo, Xiangcheng; Chung, D. D. L. (2000-01-01). "Vibration damping using flexible graphite". Carbon. 38: 1510–1512. doi:10.1016/S0008-6223(00)00111-1.
  20. ↑ "Neoprene - polychloroprene". DuPont Elastomers. Archived from the original on 2008-01-11. Retrieved 2008-04-09.
  21. ↑ "3E Protect" (PDF). MSDS.DuPont.com. Retrieved 14 October 2017.
  22. ↑ Maier, Clive; Calafut, Teresa (1998). "Additives". Polypropylene: The Definitive User's Guide and Databook. Plastics Design Library.
  23. ↑ Damon Allen.Stiffness Evaluation of Neoprene Bearing Pads under Long-Term Loads. A Dissertation Presented to the Graduate School of The University Of Florida in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy. University Of Florida 2008
  24. ↑ "Weight Systems".
  25. ↑ "Wetsuit lining". srface.com. Retrieved 28 December 2021.
  26. ↑ "Face Fabrics". PerfectEx.com. 17 April 2020. Retrieved 28 December 2021.
  27. ↑ "Steve's Corner - Hammer Tips". FenderRhodes.com. Retrieved 14 October 2017.
  28. ↑ "4 Great Drum Mutes". Making Music. February 20, 2015. Retrieved December 7, 2018.
  29. ↑ "Coronavirus Face Masks: What You Should Know". Web MD. November 8, 2019. Retrieved June 17, 2020.
  30. ↑ "RZ Mask FAQ". RZ Face Mask. March 11, 2020. Retrieved June 17, 2020.
  31. ↑ Fehr, A. R.; Perlman, S. (February 12, 2015). "Coronaviruses: An Overview of Their Replication and Pathogenesis". Coronaviruses. Methods in Molecular Biology. Vol. 1282. pp. 1–23. doi:10.1007/978-1-4939-2438-7_1. ISBN   978-1-4939-2437-0. PMC   4369385 . PMID   25720466.
  32. ↑ "A Safer Alternative Replacement for Thiourea Based Accelerators in the Production Process of Chloroprene Rubber". cordis.europa.eu. Retrieved 2024-04-25.
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