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 (Palaquium) is a genus of tropical trees native to Southeast Asia and

northern  Australasia, from Taiwan south to the Malay Peninsula and east to the Solomon

Islands. The same term is used to refer to an inelastic natural latex produced from the sap of 

these trees, particularly from the species Palaquium gutta. Chemically, gutta-percha is

a polyterpene, a polymer  of  isoprene, or  polyisoprene, specifically (trans-1,4-polyisoprene).

Heavy use of gutta-percha during the second half of the nineteenth century, particularly as

insulation for underwater telegraph cables, led to unsustainable harvesting and a collapse of 

the supply.

The word 'gutta-percha' comes from the plant's name in Malay, getah perca, which

translates as "percha sap".

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Gutta-percha was obtained from a variety of guttiferous trees throughout the Pacific

Rim although different varieties produce materials of differing quality. The differencesgenerally reflect the quantity of resin in the product with that from Pahang having the

lowest resin content. Balata has one of the highest resin contents and was obtained

from trees in the tropical regions of South America.

There is much confusion in the literature, and amongst collectors, as to “what gutta-

percha is”. In practical terms, and when addressing collectors’ items, the material is

probably the whole residue from the latex, dried after collection from whichever tree

was its source. This material tends to range from dark yellow through red to black. It

is possible that it has undergone some degree of purification but, given the variations

in initial composition, it would be extremely difficult to confirm this, even by detailed

chemical analysis.

In the same way that commercially available natural rubber is some 95% cis

polyisoprene, the crude gutta- percha was often 30% to 50% trans polyisoprene.

That is it has the same chemical “building block” as natural rubber (C5H8)n but with

a different spacial configuration. Isolation of the pure trans polyisoprene gives a

white/very pale cream “cheesy” material which looks and feels not unlike a block of 

high density polythene (m.p. about 135°C) or polypropylene (m.p. 168°C). The hard

gutta-percha softens at relativel y low temperatures (>71°C) and could then easily be

mould ed or extruded (the screw extruder was invented in 1845). At slightly lower 

temperatures, around 60°C, it can easily be cut whilst at room temperature it reverts

to a hard material.

The trees are 5 –30 metres tall and up to 1 metre in trunk diameter. The leaves

are evergreen, alternate or spirally arranged, simple, entire, 8 –25 cm long, and glossy green

above, often yellow or glaucous below. The flowers are produced in small clusters along the

stems, each flower with a white corolla with 4 –7 (mostly 6) acute lobes. The fruit is an ovoid

3 –7 cm berry, containing 1 –4 seeds; in many species the fruit is edible.In Australia, gutta-percha is a common name specifically used for the tree Excoecaria

parvifolia, which yields an aromatic, heavy, dark brown timber. It is also called "northern

birch". This particular species is not related to the palaquims

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Uses

Electronics

Gutta-percha latex is biologically inert, resilient, and is a good electrical insulator with a

high dielectric strength. The wood of many species is also valuable.

Western inventors discovered the properties of gutta-percha latex in 1842, although the localpopulation in its Malayan habitat had used it for a variety of applications for centuries.

 Allowing this fluid to evaporate and coagulate in the sun produced a latex which could be

made flexible again with hot water, but which did not become brittle, unlike rubber prior to the

discovery of vulcanization. 

By 1845, telegraph wires insulated with gutta-percha were being manufactured in the United

Kingdom. It served as the insulating material for some of the earliest undersea telegraph

cables, including the first transatlantic telegraph cable. Gutta-percha was particularly suitable

for this purpose, as it was not attacked by marine plants or animals, a problem which had

disabled previous undersea cables. The material was a major constituent of Chatterton's

compound used as an insulating sealant for telegraph and other electrical cables.Polyethylene'ssuperior insulative property has displaced it.The same bioinertness property that made it

suitable for marine cables also means it does not readily react within the human body, and

consequently it is used for a variety of surgical devices and for dental applications

during root canal therapy. It is the predominant material used to obturate, or fill the empty

space inside the root of a tooth after it has undergoneendodontic therapy. Its physical and

chemical properties, including but not limited to itsinertness and biocompatibility, melting

point, ductility and malleability, afford it an important role in the field of endodontics. 

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This material, found just a few years earlier in Malaya, was presented to Cyrus Field by

Samuel Canning who would come to be a member of the first transatlantic cable expedition.

From Samuel Canning, Mr. Field learned of the difficulties of keeping the copper wires in the

cable insulated because of the conductive medium from the ocean that surrounded the wire.Gutta-percha seemed to have the required properties for this task.

Gutta-percha was produced by evaporating the milky fluid of the guttapercha tree and

coagulating the latex from which an inelastic firm insulator resulted. This material softened

in hot water. It had a distinct advantage over India rubber that had been used in earlier 

cables because, on cooling, it became hard without becoming brittle. It was ideally suited for 

underwater use where the cold and pressure improved its insulating qualities. Submersion

also kept the cable away from sunlight which had a deteriorating effect on the cable. The

crossing of the Atlantic Ocean by cable was viewed by the scientists involved in the gutta-

percha work as the ultimate test of the material. Locally made items of this material were

brought to Europe from the Malay Peninsula and specimens were exhibited at the RoyalSociety of Arts in London in 1843. It was subsequently imported and used for various

applications, including jewellery making. The discovery of a form of rubber called gutta-

percha in 1843 led to the manufacture of a suitable insulation by 1847. In 1845, the S. W.

Silver & Co. of Stratford, East London, invented a means of extruding gutta-percha to cover 

wire (see picture below). Gutta-percha was the best cable insulation available and it was

used to insulate the telegraph lines along the Great Western Railroad in 1843. The lines

consisted of five copper conductor wires, covered with gutta-percha and supported in

wooden blocks.

The same bioinertness property that made it suitable for marine cables also means it does

not readily react within the human body, and consequently it is used for a variety of surgical

devices and for dental applications during root canal therapy. It is the predominant material

used to obturate, or fill the empty space inside the root of a tooth after it has

undergoneendodontic therapy. Its physical and chemical properties, including but not limited

to itsinertness and biocompatibility, melting point, ductility and malleability, afford it an

important role in the field of endodontics. 

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and   are different from 

Parthenium argentatum, commonly known as the Guayule , is a flowering shrub in

theaster family, Asteraceae, that is native to the southwestern United States and

northern Mexico. It can be found in the US states of New Mexico and Texas and theMexican states of Zacatecas, Coahuila, Chihuahua, San Luis Potosí, Nuevo Leon, 

and Tamaulipas.[3][4] The plant can be used as an alternate source of latex that is

also hypoallergenic, unlike the normal Hevea rubber. In pre-Columbian times, the guayule

was a secondary source of latex for rubber, the principal source being the Castilla

elastica tree. The name "guayule" derives from the Nahuatl word ulli/olli, "rubber".

Parthenium argentatum  

Scientific classification  

Kingdom: Plantae  

(unranked):  Angiosperms  

(unranked): Eudicots  

(unranked):  Asterids  

Order:  Asterales  

Family:  Asteraceae  

Genus: Parthenium  

Species: P. argentatum  

Binomial name  

Parthenium argentatum  

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Range and habitat

For sustainable production, guayule grows well in arid and semi arid areas of the southwestern United

States, North Central Mexico and regions with similar climates around the world. Because the guayule

plant produces terpene resins, which are natural pesticides, it is resistant to many pests and

diseases. Herbicides are primarily necessary for stand establishment.

Commercial rubber latex source

In the 1920s, the plant saw a brief and intense amount of agricultural research when the

Intercontinental Rubber Company in California produced 1400 tons of rubber after leaf blight

decimated the Brazilian rubber industry. Guayule would again become a replacement for Hevea  tree-

produced latex during World War II when Japan cut off America's Malaysianlatex resources. The war 

ended before large-scale farming of the guayule plant began, and the project was scrapped, as it was

cheaper to import tree-derived latex than to crush the shrubs for a smaller amount of latex.

Recently, the guayule plant has seen a small but growing resurgence in research and

agriculture due to its hypoallergenic properties. While Hevea -derived rubber 

contains proteins that can cause severe allergic reactions in a few people, guayule does not.

With the  AIDScrisis of the 1980s, the surge in rubber glove usage revealed how many

people were allergic to latex (about 10% of health care workers, according to OSHA), and

thereby created a niche market for guayule. There are synthetic alternatives for medical

device products, but they are not as stretchable as natural rubber. Guayule performs

like Hevea but contains none of the proteins that cause latex allergies.

Hypoallergenic properties

Selection of high-yielding guayule is complicated by its breeding system, which is

primarily apomixis (asexual cloning via gametes). However, the breeding system is

somewhat variable and considerable genetic variation exists within wild populations.

Selection of high-yielding lines has been successful.[5] 

Medical devices

The company leading the commercialization of guayule as an industrial crop is Yulex

Corporation, founded by Daniel R. Swiger. Yulex Corporation manufactures and produces

guayule rubber for medical devices and specialty consumer products that are safe for peoplewho have latex allergy. Yulex Corporation has cultivated proprietary, high-yielding lines of 

guayule with agricultural operations concentrated in  Arizona as well as some operations

in Queensland,  Australia. Yulex rubber is marketed as a cost-effective, clinically proven

solution to the serious health risks posed by Hevea -derived latex products.

In April 2008, the U.S. Food and Drug Administration cleared for marketing the first device

made from guayule latex, the Yulex Patient Examination Glove, which was submitted by

Yulex Corporation.

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Biofuel

Guayule's viability as a potential biofuel has been enhanced recently in light of commentary

from a variety of experts, including Lester R. Brown of the Earth Policy Institute, stating that

"[food based] biofuels pit the 800 million people with cars against the 800 million people with

hunger problems," meaning that biofuels derived from food crops (like maize) raise worldfood prices. Guayule can be an economically viable biofuel crop that does not increase the

world's hunger problem. Guayule has another benefit over food crops as biofuel - it can be

grown in areas where food crops would fail.

Hevea is a genus of flowering plants in the spurge family, Euphorbiaceous. It is also one of 

many names used commercially for the wood of the most economically important species H.brasiliensis. 

Scientific classification  

Kingdom: Plantae  

(unranked):  Angiosperms

(unranked): Eudicots 

(unranked): Rosids 

Order: Malpighiales 

Family: Euphorbiaceae  

Subfamily: Crotonoideae 

Tribe: Micrandreae  

Subtribe: Heveinae 

Genus: Hevea  

 Aubl. 

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, the Pará rubber tree, often simply called rubber tree, is

a tree belonging to the family Euphorbiaceae, and the most economically important member 

of the genus  It is of major economic importance because its sap-like extract

(known aslatex) is the primary source of  natural rubber . 

Rubber tree plantation

In the wild, the tree can reach a height of up to 100 feet (30 m). The white or yellow latex occurs in

latex vessels in the bark, mostly outside the phloem. These vessels spiral up the tree in a right-

handed helixwhich forms an angle of about 30 degrees with the horizontal, and can grow as high as

45 ft.

In plantations, the trees are kept smaller, up to 78 feet (24 m) tall, so as to use most of the

availablecarbon dioxide for latex production.

The tree requires a climate with heavy rainfall and without frost. If frost does occur, the results can be

disastrous for production. One frost can cause the rubber from an entire plantation to become brittle

and break once it has been refined.

Harvest of latex

Once the trees are 5 –6 years old, harvesting can begin: incisions are made orthogonally to the latex

vessels, just deep enough to tap the vessels without harming the tree's growth, and the sap iscollected in small buckets. This process is known as rubber tapping. Older trees yield more latex.

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