Gutta-percha
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Gutta-percha is a tree of the genus '' Palaquium'' in the family
Sapotaceae 240px, '' Madhuca longifolia'' var. ''latifolia'' in Narsapur, Medak district, India The Sapotaceae are a family of flowering plants belonging to the order (biology)">order Ericales">family (biology)">family of flowering plants belonging to th ...
, which is primarily used to create a high-quality
latex Latex is an emulsion (stable dispersion) of polymer microparticles in water. Latices are found in nature, but synthetic latices are common as well. In nature, latex is found as a wikt:milky, milky fluid, which is present in 10% of all floweri ...
of the same name. The material is rigid, naturally biologically inert, resilient, electrically nonconductive, and
thermoplastic A thermoplastic, or thermosoftening plastic, is any plastic polymer material that becomes pliable or moldable at a certain elevated temperature and solidifies upon cooling. Most thermoplastics have a high molecular weight. The polymer chains as ...
, most commonly sourced from '' Palaquium gutta''; it is a polymer of isoprene which forms a rubber-like
elastomer An elastomer is a polymer with viscoelasticity (i.e. both viscosity and elasticity) and with weak intermolecular forces, generally low Young's modulus (E) and high failure strain compared with other materials. The term, a portmanteau of ''ela ...
. The word "gutta-percha" comes from the plant's name in Malay: translates as 'sticky gum' and () is the name of a less-sought-after gutta tree. The western term therefore is likely a derivative amalgamation of the original native names.


Description

''Palaquium gutta'' trees are tall and up to in trunk diameter. The leaves are
evergreen In botany, an evergreen is a plant which has Leaf, foliage that remains green and functional throughout the year. This contrasts with deciduous plants, which lose their foliage completely during the winter or dry season. Consisting of many diffe ...
, alternate or spirally arranged, simple, entire, long, glossy green above, and often yellow or glaucous below. The flowers are produced in small clusters along the stems, each flower with a white corolla with four to seven (mostly six) acute lobes. The fruit is an ovoid berry, containing one to four seeds; in many species, the fruit is edible. In Australia, gutta-percha is a common name specifically used for the euphorbiaceous tree '' Excoecaria parvifolia'', which yields an aromatic, heavy, dark-brown timber.


Chemistry

Chemically, gutta-percha is a polyterpene, a
polymer A polymer () is a chemical substance, substance or material that consists of very large molecules, or macromolecules, that are constituted by many repeat unit, repeating subunits derived from one or more species of monomers. Due to their br ...
of isoprene, or polyisoprene, specifically ( ''trans''-1,4-polyisoprene). The cis structure of polyisoprene is the common
latex Latex is an emulsion (stable dispersion) of polymer microparticles in water. Latices are found in nature, but synthetic latices are common as well. In nature, latex is found as a wikt:milky, milky fluid, which is present in 10% of all floweri ...
elastomer An elastomer is a polymer with viscoelasticity (i.e. both viscosity and elasticity) and with weak intermolecular forces, generally low Young's modulus (E) and high failure strain compared with other materials. The term, a portmanteau of ''ela ...
. While latex rubbers are
amorphous In condensed matter physics and materials science, an amorphous solid (or non-crystalline solid) is a solid that lacks the long-range order that is a characteristic of a crystal. The terms "glass" and "glassy solid" are sometimes used synonymousl ...
in molecular structure, gutta-percha (the trans structure)
crystal A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macros ...
lizes, leading to a more rigid material. It exists in alpha and beta forms, with the alpha form being brittle at room temperature.


Uses


Historic

Long before gutta-percha was introduced into the Western world, it was used in a less-processed form by the natives of the Malaysian archipelago for making knife handles, walking sticks, and other purposes. The first European to study this material was John Tradescant, who collected it in the far east in 1656. He named this material "Mazer wood". William Montgomerie, a medical officer in imperial service, introduced gutta-percha into practical use in the West. He was the first to appreciate the potential of this material in medicine, and he was awarded the gold medal by the Royal Society of Arts, London in 1843.Harvey Wickes Felter and John Uri Lloyd
"Gutta-Percha-: An Untold Story. Prakesh et al. ~2001 Endodontology"
King's American Dispensatory.
Scientifically classified in 1843, it was found to be a useful natural
thermoplastic A thermoplastic, or thermosoftening plastic, is any plastic polymer material that becomes pliable or moldable at a certain elevated temperature and solidifies upon cooling. Most thermoplastics have a high molecular weight. The polymer chains as ...
. In 1851, of gutta-percha was imported into Britain. During the second half of the 19th century, gutta-percha was used for many domestic and industrial purposes, and it became a household word. Gutta-percha was particularly important for the manufacture of underwater telegraph cables.Bill Burns
The Gutta Percha Company
atlantic-cable.com, accessed 6 October 2010.
Compared to rubber, it does not degrade in seawater, is not damaged by marine life, and maintains good
electrical insulation Electricity is the set of physical phenomena associated with the presence and motion of matter possessing an electric charge. Electricity is related to magnetism, both being part of the phenomenon of electromagnetism, as described by ...
. These properties, along with its mouldability and flexibility made it ideal for the purpose, with no other material to match it in the 19th century. The use in electrical cables generated a huge demand which led to unsustainable harvesting and collapse of supply.


Electrical

Gutta-percha latex is biologically inert, resilient, and is a good electrical insulator with a high dielectric strength.
Michael Faraday Michael Faraday (; 22 September 1791 – 25 August 1867) was an English chemist and physicist who contributed to the study of electrochemistry and electromagnetism. His main discoveries include the principles underlying electromagnetic inducti ...
discovered its value as an insulator soon after the introduction of the material to Britain in 1843. 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 Rubber, also called India rubber, latex, Amazonian rubber, ''caucho'', or ''caoutchouc'', as initially produced, consists of polymers of the organic compound isoprene, with minor impurities of other organic compounds. Types of polyisoprene ...
prior to the discovery of vulcanization. By 1845, telegraph wires insulated with gutta-percha were being manufactured in the UK. It served as the insulating material for early undersea telegraph cables, including the first transatlantic telegraph cable. The material was a major constituent of Chatterton's compound used as an insulating sealant for telegraph and other electrical cables. The dielectric constant of dried gutta-percha ranges from 2.56 to 3.01. Resistivity of dried gutta-percha ranges from to . Since about 1940,
polyethylene Polyethylene or polythene (abbreviated PE; IUPAC name polyethene or poly(methylene)) is the most commonly produced plastic. It is a polymer, primarily used for packaging (plastic bags, plastic films, geomembranes and containers including bott ...
has supplanted gutta-percha as an electrical insulator.


Other

In the mid-19th century, gutta-percha was used to make furniture, notably by the Gutta Percha Company, established in 1847. Several of these ornate, revival-style pieces were shown at the 1851
Great Exhibition The Great Exhibition of the Works of Industry of All Nations, also known as the Great Exhibition or the Crystal Palace Exhibition (in reference to the temporary structure in which it was held), was an international exhibition that took ...
in Hyde Park, London. The company also made a range of utensils. The " guttie" golf ball (which had a solid gutta-percha core) revolutionized the game. Gutta-percha was used to make "mourning" jewelry, because it was dark in color and could be easily molded into beads or other shapes. Pistol hand grips and rifle shoulder pads were also made from gutta-percha, since it was hard and durable, though it fell into disuse when synthetic
plastic Plastics are a wide range of synthetic polymers, synthetic or Semisynthesis, semisynthetic materials composed primarily of Polymer, polymers. Their defining characteristic, Plasticity (physics), plasticity, allows them to be Injection moulding ...
s such as Bakelite became available. Gutta-percha was used in canes and walking sticks. In 1856, United States Representative Preston Brooks used a cane made of gutta-percha as a weapon in his attack on Senator
Charles Sumner Charles Sumner (January 6, 1811March 11, 1874) was an American lawyer and statesman who represented Massachusetts in the United States Senate from 1851 until his death in 1874. Before and during the American Civil War, he was a leading American ...
. In the 1860s, gutta-percha was used to reinforce the soles of football players' boots before it was banned by
The Football Association The Football Association (the FA) is the Sports governing body, governing body of association football in England and the Crown Dependencies of Jersey, Bailiwick of Guernsey, Guernsey and the Isle of Man. Formed in 1863, it is the oldest footb ...
in the first codified set of rules in 1863. Gutta-percha was briefly used in
bookbinding Bookbinding is the process of building a book, usually in codex format, from an ordered stack of paper sheets with one's hands and tools, or in modern publishing, by a series of automated processes. Firstly, one binds the sheets of papers alon ...
until the advent of vulcanization. The wood of many species is also valuable.


Today


Art

Gutta-percha is used as a resist in silk painting, including some newer forms of batik.


Dentistry

The same bioinertness that made it suitable for marine cables also means it does not readily react within the human body. It is used in a variety of surgical devices and 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 undergone endodontic therapy. Its physical and chemical properties, including its inertness and biocompatibility,
melting point The melting point (or, rarely, liquefaction point) of a substance is the temperature at which it changes state of matter, state from solid to liquid. At the melting point the solid and liquid phase (matter), phase exist in Thermodynamic equilib ...
,
ductility Ductility refers to the ability of a material to sustain significant plastic Deformation (engineering), deformation before fracture. Plastic deformation is the permanent distortion of a material under applied stress, as opposed to elastic def ...
, and
malleability Ductility refers to the ability of a material to sustain significant plastic Deformation (engineering), deformation before fracture. Plastic deformation is the permanent distortion of a material under applied stress, as opposed to elastic def ...
, make it important in
endodontics Endodontics () is the Specialty (dentistry), dental specialty concerned with the study and treatment of the dental pulp. Overview Endodontics encompasses the study (practice) of the basic and clinical sciences of normal dental pulp, the etiolo ...
, e.g., as gutta-percha points.
Zinc oxide Zinc oxide is an inorganic compound with the Chemical formula, formula . It is a white powder which is insoluble in water. ZnO is used as an additive in numerous materials and products including cosmetics, Zinc metabolism, food supplements, rubbe ...
is added to reduce brittleness and improve plasticity. Barium sulfate is added to provide radiopacity so that its presence and location can be verified in dental X-ray images.


Substitutes

Gutta-percha remained an industrial staple well into the 20th century, when it was gradually replaced with superior synthetic materials, such as Bakelite. A similar and cheaper natural material called '' balatá'' was often used in gutta-percha's place. The two materials are almost identical, and ''balatá ''is often called ''gutta-balatá''.


See also

*
Natural rubber Rubber, also called India rubber, latex, Amazonian rubber, ''caucho'', or ''caoutchouc'', as initially produced, consists of polymers of the organic compound isoprene, with minor impurities of other organic compounds. Types of polyisoprene ...
*'' Gutta-percha Boy'', a 1957 Soviet drama film


References


External links


Germplasm Resources Information Network: ''Palaquium''The Gutta Percha Company on the History of the Atlantic Cable site
* {{authority control Palaquium Rubber Endodontics