Neoprene

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

* 1 Production
* 2 History
* 3 Mechanical properties
* 4 Applications
* 4.1 General
* 4.2 Civil engineering
* 4.3 Aquatics
* 4.4 Home accessories
* 4.5 Music
* 4.6 Hydroponic gardening
* 4.7 Face mask
* 4.8 Other
* 5 Precautions
* 6 See also
* 7 References
* 8 External links

## 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. During his work on acetylene, Nieuwland 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] The demand for the material rose very rapidly: in 1932, approximately 8,000 pounds of neoprene were produced, in 1933 approximately 52,000 pounds were produced, and this amount doubled annually for the following five years.[8]

For quality control, 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".[9] 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 $6,800,000 in 2024).[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.[10] A two parameter (strain rate and temperature) hyperelastic model can accurately capture much of the mechanical response of neoprene.[11]

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.[12] 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.[13] Chain scission leads to degradation, embrittlement, and a loss of toughness.[14] Oxidation reactions in the presence of heating leads to increased cross-linking, which in turn causes hardening.[13] The interplay of both these factors determines the resulting effect on material mechanical properties; cross-linking is thought to dominate for neoprene.[13][15]

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, deteriorates its mechanical properties.[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  Property  | Value

|

Ultimate tensile strength  | 27.579 MPa (4000 psi)[10]
Young's modulus  | 6.136 MPa (890 psi)[18]
Ultimate elongation  | 600%[10]
Hardness (Durometer)  | 30–95[10]
Glass transition temperature  | -43°C[10]
Storage modulus (measured at 1 Hz)  | 7.83 MPa (1135.646 psi)[19]
Loss modulus (measured at 1 Hz)  | 8.23 MPa (1193.661 psi) [19]

## Applications

### General

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]

Polychloroprene is used in medical gloves and is often marketed for its superior elasticity, comfort and durability when compared to nitrile, while still being safe for those allergic to natural latex.

### 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 thermal insulation. The foam is quite buoyant, and divers compensate for this by wearing weights.[24] Foam neoprene compresses under pressure.[25]

Some wetsuits are of the "super-flex" variety, which uses spandex in the knit liner fabric.[26][27] 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.

### Home accessories

Neoprene is used 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.[28]

Neoprene is also used for speaker cones and drum practice pads.[29]

### 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.

### 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.[30] Some commercial face mask manufacturers that use neoprene have claimed 99.9% filtration for particles as small as 0.1 microns.[31] The size of coronavirus is identified to be on average 0.125 microns.[32]

### Other

Template:Cite section

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,[33] Balenciaga,[34] 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.[35]

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.[36]

## See also

* Isoprene

## References

1. ↑ 1.0 1.1 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". Du Pont Performance Elastomers. October 2003. http://www.dupontelastomers.com/literature/neoprene/585E7A59DA93810F6B1A7900D3712585.pdf.
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. Bibcode: 1931JAChS..53.4203C.
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.
6. ↑ "Neoprene: 1930 - Overview". DuPont Heritage. DuPont. http://www2.dupont.com/Heritage/en_US/1930_dupont/1930_neoprene_overview.html.
7. ↑ 7.0 7.1 7.2 7.3 7.4 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. https://archive.org/details/sciencecorporate0008houn/page/253.
8. ↑ Smith, John K. (1985). "The Ten-Year Invention: Neoprene and Du Pont Research, 1930-1939". Technology and Culture 26 (1): 34–55. doi:10.2307/3104528. ISSN 0040-165X. https://www.jstor.org/stable/3104528.
9. ↑ "Neoprene: 1930 - In Depth". DuPont Heritage. DuPont. http://www2.dupont.com/Heritage/en_US/1930_dupont/1930_neoprene_indepth.html.
10. ↑ 10.0 10.1 10.2 10.3 10.4 Harris, Cyril M., ed (2002). Harris' shock and vibration handbook. McGraw-Hill handbooks (5th ed.). New York: McGraw-Hill. pp. Ch. 33. ISBN 978-0-07-137081-3.
11. ↑ Trivedi, A. R.; Siviour, C. R. (2020-09-01). "A Simple Rate–Temperature Dependent Hyperelastic Model Applied to Neoprene Rubber" (in en). Journal of Dynamic Behavior of Materials 6 (3): 336–347. doi:10.1007/s40870-020-00252-w. ISSN 2199-7454. Bibcode: 2020JDBM....6..336T. https://ora.ox.ac.uk/objects/uuid:25a50866-cedb-4da6-aff5-7980300c3d3c.
12. ↑ Gao, Pengfei; Tomasovic, Beth (November 2005). "Change in Tensile Properties of Neoprene and Nitrile Gloves After Repeated Exposures to Acetone and Thermal Decontamination" (in en). Journal of Occupational and Environmental Hygiene 2 (11): 543–552. doi:10.1080/15459620500315964. ISSN 1545-9624. PMID 16276643. Bibcode: 2005JOEH....2..543G. http://www.tandfonline.com/doi/abs/10.1080/15459620500315964. Retrieved 2024-05-13.
13. ↑ 13.0 13.1 13.2 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" (in en). Journal of Polymer Research 31 (4): 102. doi:10.1007/s10965-024-03910-y. ISSN 1572-8935. https://doi.org/10.1007/s10965-024-03910-y.
14. ↑ Fayolle, Bruno; Richaud, Emmanuel; Colin, Xavier; Verdu, Jacques (2008). "Review: degradation-induced embrittlement in semi-crystalline polymers having their amorphous phase in rubbery state" (in en). Journal of Materials Science 43 (22): 6999–7012. doi:10.1007/s10853-008-3005-3. ISSN 0022-2461. Bibcode: 2008JMatS..43.6999F. https://link.springer.com/10.1007/s10853-008-3005-3. Retrieved 2024-05-13.
15. ↑ 15.0 15.1 Ito, Masayuki; Okada, Sohei; Kuriyama, Isamu (1981-01-01). "The deterioration of mechanical properties of chloroprene rubber in various conditions" (in en). Journal of Materials Science 16 (1): 10–16. doi:10.1007/BF00552053. ISSN 1573-4803. Bibcode: 1981JMatS..16...10I. https://doi.org/10.1007/BF00552053. Retrieved 2024-05-13.
16. ↑ Scagliusi, Sandra; Araújo, Sumair G.; Landini, Liliane; Lugão, Ademar B. (2009). "STUDY OF PROPERTIES OF CHLOROPRENE RUBBER DEVULCANIZATE BY RADIATION IN MICROWAVE". 2009 International Nuclear Atlantic Conference. https://inis.iaea.org/collection/NCLCollectionStore/_Public/41/097/41097057.pdf. Retrieved 2024-05-13.
17. ↑ Chou, Hsoung-Wei; Huang, Jong-Shin (2008-12-05). "Effects of ultraviolet irradiation on the static and dynamic properties of neoprene rubbers" (in en). Journal of Applied Polymer Science 110 (5): 2907–2913. doi:10.1002/app.28903. ISSN 0021-8995. Bibcode: 2008JAPS..110.2907C. https://onlinelibrary.wiley.com/doi/10.1002/app.28903. Retrieved 2024-05-13.
18. ↑ "MatWeb - The Online Materials Information Resource". https://www.matweb.com/errorUser.aspx?msgid=2&ckck=nocheck.
19. ↑ 19.0 19.1 Luo, Xiangcheng; Chung, D. D. L. (2000-01-01). "Vibration damping using flexible graphite". Carbon 38 (10): 1510–1512. doi:10.1016/S0008-6223(00)00111-1. Bibcode: 2000Carbo..38.1510L. https://ui.adsabs.harvard.edu/abs/2000Carbo..38.1510L. Retrieved 2024-05-13.
20. ↑ "Neoprene - polychloroprene". DuPont Elastomers. http://www.dupontelastomers.com/Products/neoprene/neoprene.asp?id=wikineo.
21. ↑ "3E Protect". http://msds.dupont.com/msds/pdfs/EN/PEN_09004a35803d9eb8.pdf.
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". https://www.ndiver.com/diving-equipment/weights.
25. ↑ "Neoprene foam types for all applications-What foam is right for you?" (in en-US). 2017-03-04. https://www.macrointlco.com/neoprene/neoprene-foam-types.
26. ↑ "Wetsuit lining". https://srface.com/knowledge-base/wetsuit-lining/.
27. ↑ "Face Fabrics". 17 April 2020. https://www.perfectex.com/neoprene-laminated-fabrics/.
28. ↑ "Steve's Corner - Hammer Tips". https://www.fenderrhodes.com/service/hammer-tips.html.
29. ↑ "4 Great Drum Mutes". February 20, 2015. https://makingmusicmag.com/4-great-drum-mutes/.
30. ↑ "Coronavirus Face Masks: What You Should Know". November 8, 2019. https://www.webmd.com/covid/coronavirus-face-masks.
31. ↑ "RZ Mask FAQ". March 11, 2020. https://rzmask.com/pages/faq.
32. ↑ Fehr, A. R.; Perlman, S. (February 12, 2015). "Coronaviruses: An Overview of Their Replication and Pathogenesis". Coronaviruses. Methods in Molecular Biology. 1282. pp. 1–23. doi:10.1007/978-1-4939-2438-7_1. ISBN 978-1-4939-2437-0.
33. ↑ "Dress | Gareth Pugh". December 2, 2011. https://collections.vam.ac.uk/item/O1242051/dress-gareth-pugh/.
34. ↑ "Dress | Nicolas Ghesquière". December 2, 2011. https://collections.vam.ac.uk/item/O1242046/dress-nicolas-ghesquière/.
35. ↑ Stern, E. B.; Callinan, N.; Hank, M.; Lewis, E. J.; Schousboe, J. T.; Ytterberg, S. R. (1998). "Neoprene splinting: dermatological issues". The American Journal of Occupational Therapy 52 (7): 573–578. doi:10.5014/ajot.52.7.573. ISSN 0272-9490. PMID 9693703.
36. ↑ "A Safer Alternative Replacement for Thiourea Based Accelerators in the Production Process of Chloroprene Rubber". https://cordis.europa.eu/project/id/243756.

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* DuPont Performance Elastomers, L.L.C. historical files on Neoprene, at Hagley Museum and Library

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