Vulcanization

Vulcanization (vulcanisation in Europe) is the process of cross-linking elastomer molecules to make the bulk material harder, less soluble and more durable. It is also called curing. It is the heart of the art and science of rubber compounding.

Vulcanisation is a chemical process in which individual polymer molecules are linked to other polymer molecules by atomic bridges. The end result is that the springy rubber molecules become locked together to a greater or lesser extent. This makes the bulk material [harder], much more durable and also more resistant to chemical attack. It also transforms the surface of the material from a sticky, yucky feel to a smooth, soft surface which does not adhere to metal or plastic substrates.

Vulcanisation is an irreversible process, like baking a cake, and must be contrasted strongly with thermoplastic processes (the melt-freeze cycle) which characterise the behaviour of the vast majority of modern polymers. This irreversible cure reaction defines cured rubber compounds as thermoset materials, which do not melt on heating, and places them outside the class of thermoplastic materials (like polyethylene and polypropylene). This is a fundamental difference between rubbers and plastics, and sets the conditions for their applications in the real world, their costs, and the economics of their supply and demand.

Usually, the actual chemical cross-linking is done with sulphur (sulfur in the US-speaking world), but there are other technologies, including peroxide-based systems. The combined cure package in a typical [rubber] compound comprises the cure agent itself, (sulphur or peroxide), together with accelerators and retarding agents. More on these later.

Sulphur is an unusual material. Given the right circumstances, it will form chains composed of strings of its own atoms. Carbon and silicon can also form such chains. The curing process makes use of this [phenomenon]. Along the rubber molecule, there are a number of sites which are attractive to sulphur atoms. These are called cure sites. At each cure site on the rubber molecule, a sulphur atom can attach itself, and from there, a sulphur chain can grow, until it eventually reaches a cure site on another rubber molecule. These sulphur bridges are typically between 2 and 10 atoms long. Contrast this with typical polymer molecules in which the carbon backbone is many thousands of atomic units in length.

Overview and history

The history of rubber goes back to prehistoric times, when the Aztecs and Mayans bled natural rubber latex from the Hevea brasiliensis trees in the local forests, formed the gunk into balls, and played the Mesoamerican ball game with the resulting bouncy balls. The losers were sometimes ritually executed. Those balls cannot have lasted much longer than the losing players. Uncured natural rubber turns very smelly within a few days as it starts to rot. The rotting process is partly to do with proteins being broken down much as milk proteins do, but also due to the large rubber molecules breaking up as they oxidise in the air. (Chain scission, for the technically-minded)

The first reference to rubber in Europe appears to be in 1770, when Edward Nairne was selling cubes of natural rubber from his shop at 20 Cornhill in London. The cubes, meant to be erasers, sold for the astonishingly high price of 3 shillings per half-inch cube.

From these early days to the mid-19th century, rubber was a novelty material, but it did not find much application in the industrial world. It was used first as erasers, and then as medical devices for connecting tubes and for inhaling [medicinal] gases. With the discovery that rubber was soluble in ether, it found applications in waterproof coatings, notably for shoes and soon after this, the rubberised Mackintosh coat became very popular.

Nevertheless, most of these applications were in small volumes and the material did not last long. The reason for this lack of serious applications was the fact that the material was not durable, was sticky and often rotted and smelled bad because it remained in its uncured state.

Goodyear's contribution

Most textbooks have it that an American called Charles Goodyear (1800-1860) was first to use sulphur to vulcanise rubber. Depending on who you read, the Goodyear story is either one of pure luck, or one of careful research. Goodyear insists that it was the latter, though there are many contemporaneous accounts which indicate the former.

Goodyear claimed he discovered sulphur-based vulcanisation in 1839, but did not patent the invention until July 5, 1843, and did not write the story of the discovery until 1853 in his autobiographical book, Gum-Elastica. Meanwhile, a Scottish scientist and engineer, Thomas Hancock (1786-1865) patented the process in the UK on November 21, 1843, eight weeks before Goodyear applied for his own UK patent.

Goodyear was a bit of a drifter with no serious scientific or industrial credentials, while Hancock was an accomplished scientist and engineer and developed many of the machines used to process rubber in its early days. The Goodyear Tire and Rubber Company adopted the Goodyear name because of its activities in the rubber industry, but it has no other links to Charles Goodyear and his family.

Here is Goodyear's account of the invention, taken from Gum-Elastica. Although the book is an autobiography, Goodyear chose to write it in the third person, so that 'the inventor' and 'he' referred to in the text are in fact, the author. He describes the scene in a rubber factory where his brother worked.

...The inventor made some experiments to ascertain the effect of heat on the same compound that had decomposed in the mail-bags and other articles. He was surprised to find that the specimen, being carelessly brought into contact with a hot stove, charred like leather.

Goodyear goes on to describe how he attempted to call the attention of his brother and other workers in the plant who were familiar with the behaviour of dissolved rubber, but they dismissed his appeal as unworthy of their attention, believing it to be one of the many appeals he made to them on account of some strange experiment. Goodyear claims he tried to tell them that dissolved rubber usually melted when heated excessively, but they still ignored him.

He directly inferred that if the process of charring could be stopped at the right point, it might divest the gum of its native adhesiveness throughout, which would make it better than the native gum. Upon further trial with heat, he was further convinced of the correctness of this inference, by finding that the India rubber could not be melted in boiling sulphur at any heat ever so great, but always charred.
He made another trial of heating a similar fabric before an open fire. The same effect, that of charring the gum, followed; but there were further and very satisfactory indications of success in producing the desired result, as upon the edge of the charred portion appeared a line or border, that was not charred, but perfectly cured.

Goodyear then goes on to describe how he moved to Woburn, Massachusetts and carried out a series of systematic experiments to discover the right conditions for curing rubber.

...On ascertaining to a certainty that he had found the object of his search and much more, and that the new substance was proof against cold and the solvent of the native gum, he felt himself amply repaid for the past, and quite indifferent to the trials of the future.

Goodyear never made any money out of his invention. He pawned all his family's possessions in an effort to raise money, but on July 1, 1860, he died with debts of over $200,000.

Subsequent developments

Whatever the true history, the discovery of the rubber-sulphur reaction revolutionised the use and applications of rubber, and changed the face of the industrial world.

Up to that time, the only way to seal a small gap on a rotating machine, or ensure that the gas (usually steam) in a cylinder applied its force to the piston with minimal leakage was by using leather soaked in oil. This was acceptable up to moderate pressures, but above a certain point, machine designers had to compromise between the extra friction generated by packing the leather ever more tightly, or face greater leakage of the precious steam.

Vulcanised rubber offered the ideal solution. With vulcanised rubber, engineers had a material which could be shaped and formed to precise shapes and dimensions, and which would accept moderate to large deformations under load, and recover quickly to its original dimensions once the load was removed. These, combined with good durability and lack of stickiness are the critical requirements for an effective sealing material.

Further experiments in the processing and compounding of rubber were carried out, mostly in the UK by Hancock and his colleagues, and these led to a more repeatable and stable process.

In 1905, however, another American, George Oenslager , discovered that a derivative of aniline called thiocarbanilide was able to accelerate the action of sulphur on the rubber, leading to much shorter cure times and reduced energy consumption. This work, though much less well-known, is almost as fundamental to the development of the rubber industry as that of Goodyear in discovering the sulphur cure. Accelerators made the cure process much more reliable and more repeatable. One year after his discovery, Oenslager had found hundreds of potential applications for his additive.

Thus, the science of accelerators and retarders was born. An accelerator speeds up the cure reaction, while a retarder delays it. In the subsequent century, various chemists have developed other accelerators, and so-called ultra-accelerators, that make the reaction very fast, and are used in the compounds used to make most modern rubber goods.

Commercial Usage: Vulcanization

Usage Frequency: Vulcanization

Expression: Vulcanization

Frequency of Internet Keywords: Vulcanization

Modern Translations: Vulcanization

Language		Translations for "vulcanization"; alternative meanings/domain in parentheses.
Arabic		‏الفلكنة تقسية المطاط. (various references)

Bulgarian		вулканизация (metallization). (various references)

Danish		vulkanisering (cure, vulcanisation), brodannelse (and electron bombardment, bridging, bridging of hole, cross-linking, doming, the establishing of chemical links between the molecular chains in polymers.It can be accomplished by chemical reaction). (various references)

Dutch		vulcanisatie (cure, curing, vulcanisation), kruisverbinding (and electron bombardment, cross-linking, distributor, the establishing of chemical links between the molecular chains in polymers.It can be accomplished by chemical reaction). (various references)

Finnish		silloitus (and electron bombardment, cross-linking, tacking of edges, the establishing of chemical links between the molecular chains in polymers.It can be accomplished by chemical reaction), ristiliittyminen (and electron bombardment, cross-linking, the establishing of chemical links between the molecular chains in polymers.It can be accomplished by chemical reaction). (various references)

French		vulcanisation (vulcanisation). (various references)

German		Vulkanisation (cure, curing, vulcanisation). (various references)

Greek		εκθείωση καουτσούκ, αναγόμωση (rebasing, retread), δικτύωση (and electron bombardment, cross-linking, reticulating, reticulation, scorching, the establishing of chemical links between the molecular chains in polymers.It can be accomplished by chemical reaction). (various references)

Hebrew		�'פור (fumigation, sulphurization). (various references)

Hungarian		vulkanizálás (cure, curing), vulkanizáció, vulkánozás (cure). (various references)

Italian		vulcanizzazione (cure, curing, vulcanisation). (various references)

Japanese Kanji		硬化 (hardening, sclerosis). (various references)

Japanese Katakana		かりゅうほう, �"うか (chrysanthemum, coin, depression, descent, effect, effectiveness, efficacy, engineering course, evaluation, fall, furlough, gelatinization, hardening, high price, landing, leave of absence, loud singing, marriage of an Imperial princess to a subject, merits and demerits, mineralize, overhead structure, public imposts, rating, result, school song, sclerosis, taxes, toilet, Yellow Peril). (various references)

Korean		경�" (vulcanisation). (various references)

Manx		vulcaanaghey (vulcanize). (various references)

Pig Latin		ulcanizationvay

Portuguese		vulcanização (cure, curing, setting, vulcanisation). (various references)

Romanian		vulcanizare. (various references)

Serbo-Croatian		vulkanizacija (tire-repair). (various references)

Spanish		vulcanización (cure, curing, vulcanisation). (various references)

Swedish		vulkanisering, tvärbindning (and electron bombardment, cross-linking, the establishing of chemical links between the molecular chains in polymers.It can be accomplished by chemical reaction), förnätning (and electron bombardment, cross-linking, the establishing of chemical links between the molecular chains in polymers.It can be accomplished by chemical reaction). (various references)

Ukranian		вулканізація. (various references)
Source: compiled by the editor from various translation references.

Derivations & Misspellings: Vulcanization

Rhyming with "Vulcanization"

Anagrams: Vulcanization

Alternative Orthography: Vulcanization

Hexadecimal (or equivalents, 770AD-1900s) (references)

56 75 6C 63 61 6E 69 7A 61 74 69 6F 6E

Leonardo da Vinci (1452-1519; backwards) (references)

American Sign Language (origins from 1620-1817 in Italy and, especially, France) (references)

⁼

Semaphore (1791, in France) (references)

Braille (1829, in France) (references)

Morse Code (1836) (references)

...- ..- .-.. -.-. .- -. .. --.. .- - .. --- -.

Dancing Men (Sir Arthur Conan Doyle, 1903) (references)

Binary Code (1918-1938, probably earlier) (references)

01010110 01110101 01101100 01100011 01100001 01101110 01101001 01111010 01100001 01110100 01101001 01101111 01101110

HTML Code (1990) (references)

&#86 &#117 &#108 &#99 &#97 &#110 &#105 &#122 &#97 &#116 &#105 &#111 &#110

ISO 10646 (1991-1993) (references)

0056 0075 006C 0063 0061 006E 0069 007A 0061 0074 0069 006F 006E

British Sign Language (Fingerspelling, BSL; 1992, British Deaf Association Dictionary of British Sign Language) (references)

Encryption (beginner's substitution cypher): (references)

Domain	Title
Books	Vulcanization and vulcanizing agents (reference) Vulcanization of Elastomers: Principles and Practice of Vulcanization of Commercial Rubbers (reference) Vulcanization with urethane reagents (reference) (more book examples)
Source: compiled by the editor from various references; see credits.

Parts of Speech	Percent	Usage per 100 Million Words	Rank in English
Noun (singular)	100%	2	245,945

Expression	Frequency per Day
vulcanization	12
rubber vulcanization	4
cable continuous vulcanization	2
Source: compiled by the editor from various references; see credits.

Derivations
	Words beginning with "vulcanization": vulcanizations. (additional references)
Misspellings
	"Vulcanization" is suggested in spellcheckers for the following: villagization. (additional references)
Source: compiled by the editor, based on several corpora (additional references).

Scrabble® Enable2K-Verified Anagrams
	Words within the letters "a-a-c-i-i-l-n-n-o-t-u-v-z"
	-4 letters: clintonia, continual, incaution, inoculant, nicotiana, valuation, vaticinal, vulcanian.
	-5 letters: actinian, aviation, cantonal, continua, countian, inaction, lavation, lunation, national, nautical, outcavil, univocal, vacation, viatical.
	Words containing the letters "a-a-c-i-i-l-n-n-o-t-u-v-z"
	+1 letter: vulcanizations.
Source: compiled by the editor from various references; see credits. SCRABBLE® is a registered trademark. All intellectual property rights in and to the game are owned in the U.S.A and Canada by Hasbro Inc., and throughout the rest of the world by J.W. Spear & Sons Limited of Maidenhead, Berkshire, England, a subsidiary of Mattel Inc. Mattel and Spear are not affiliated with Hasbro.

Expression using "vulcanization": vulcanization pan. Additional references.
Source: compiled by the editor from various references; see credits.

Vulcanization

Definition: Vulcanization

Vulcanization

Noun

Synonym: Vulcanization

Specialty Definition: Vulcanization

Overview and history

Goodyear's contribution

Subsequent developments

Crosswords: Vulcanization

Commercial Usage: Vulcanization

Books

Usage Frequency: Vulcanization

Expression: Vulcanization

Frequency of Internet Keywords: Vulcanization

vulcanization

rubber vulcanization

cable continuous vulcanization

Modern Translations: Vulcanization

Arabic

Bulgarian

Danish

Dutch

Finnish

French

German

Greek

Hebrew

Hungarian

Italian

Japanese Kanji

Japanese Katakana

Korean

Manx

Pig Latin

Portuguese

Romanian

Serbo-Croatian

Spanish

Swedish

Ukranian

Derivations & Misspellings: Vulcanization

Derivations

Misspellings

Rhyming with "Vulcanization"

Anagrams: Vulcanization

Scrabble® Enable2K-Verified Anagrams

Alternative Orthography: Vulcanization

56 75 6C 63 61 6E 69 7A 61 74 69 6F 6E

...- ..- .-.. -.-. .- -. .. --.. .- - .. --- -.

01010110 01110101 01101100 01100011 01100001 01101110 01101001 01111010 01100001 01110100 01101001 01101111 01101110

&#86 &#117 &#108 &#99 &#97 &#110 &#105 &#122 &#97 &#116 &#105 &#111 &#110

0056 0075 006C 0063 0061 006E 0069 007A 0061 0074 0069 006F 006E

56877869678075926786758180

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