طبرخي

(تم التحويل من Gutta-percha)
Palaquium gutta

Gutta-percha is a tree of the genus Palaquium in the family Sapotaceae. The name also refers to the rigid, naturally biologically inert, resilient, electrically nonconductive, thermoplastic latex derived from the tree, particularly from Palaquium gutta; it is a polymer of isoprene which forms a rubber-like elastomer.

The word "gutta-percha" comes from the plant's name in Malay: getah translates as 'sticky gum' and pertja (perca) is the name of a less-sought-after gutta tree. The western term therefore is likely a derivative amalgamation of the original native names.[1]

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الوصف

Gutta-percha tree

Palaquium gutta trees are 5–30 metres (20–100 ft) tall and up to 1 m (3 ft) in trunk diameter. The leaves are evergreen, alternate or spirally arranged, simple, entire, 8–25 cm (3–10 in) 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 3–7 cm (1–3 in) 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.


الكيمياء

Chemical structure of gutta-percha[2]

Chemically, gutta-percha is a polyterpene, a polymer of isoprene, or polyisoprene, specifically (trans-1,4-polyisoprene).[3] The cis structure of polyisoprene is the common latex elastomer.[3] While latex rubbers are amorphous in molecular structure, gutta-percha (the trans structure) crystallizes, leading to a more rigid material. It exists in alpha and beta forms, with the alpha form being brittle at room temperature.[4]

الاستخدامات

التاريخية

Cable manufacturing with gutta-percha at the Telegraph Construction and Maintenance Company in Greenwich, London, circa 1865
Members of a Kayan tribe in Borneo harvesting the sap of a gutta-percha tree ح. 1910

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.[5]

Scientifically classified in 1843, it was found to be a useful natural thermoplastic. In 1851, 30,000 long cwt (1,500 t) of gutta-percha was imported into Britain.[6] During the second half of the 19th century, gutta-percha was used for many domestic and industrial purposes,[7] and it became a household word. Gutta-percha was particularly important for the manufacture of underwater telegraph cables.[6] Compared to rubber, it does not degrade in seawater, is not damaged by marine life, and maintains good electrical insulation.[8] 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.[9] The use in electrical cables generated a huge demand which led to unsustainable harvesting and collapse of supply.[10]

الكهربائية

Gutta-percha latex is biologically inert, resilient, and is a good electrical insulator with a high dielectric strength.[8]

Michael Faraday discovered its value as an insulator soon after the introduction of the material to Britain in 1843.[11] 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.[بحاجة لمصدر]

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.[12] The material was a major constituent of Chatterton's compound[13] used as an insulating sealant for telegraph and other electrical cables.[بحاجة لمصدر]

The dielectric constant of dried gutta-percha ranges from 2.56 to 3.01. Resistivity of dried gutta-percha ranges from 25×1014 to 370×1014 Ω⋅cm. [14]

Since about 1940, polyethylene has supplanted gutta-percha as an electrical insulator.[15]

غيرهم

Lithograph depicting the caning of Charles Sumner with a cane made of gutta-percha
The gutta-percha cane used by Preston Brooks to attack Charles Sumner on the floor of the United States Senate in 1856 (in the collection of the Old State House museum, Boston, Massachusetts)

In the mid-19th century, gutta-percha was used to make furniture, notably by the Gutta Percha Company, established in 1847.[6] Several of these ornate, revival-style pieces were shown at the 1851 Great Exhibition in Hyde Park, London. The company also made a range of utensils.[16]

The "guttie" golf ball (which had a solid gutta-percha core) revolutionized the game.[17] Gutta-percha was used to make "mourning" jewelry, because it was dark in color and could be easily molded into beads or other shapes.[18] 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 plastics 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.[19]

In the 1860s, gutta-percha was used to reinforce the soles of football players' boots before it was banned by The Football Association in the first codified set of rules in 1863.[20]

Gutta-percha was briefly used in bookbinding until the advent of vulcanization.[21]

The wood of many species is also valuable.[بحاجة لمصدر]

اليوم

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الفن

Gutta-percha is used as a resist in silk painting,[22][23] including some newer forms of batik.

طب الأسنان

Gutta-percha points used in 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,[24] ductility, and malleability, make it important in endodontics,[5] e.g., as gutta-percha points. Zinc oxide 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.

البدائل

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.[بحاجة لمصدر]

انظر أيضاً

المراجع

  1. ^ Thulaja, Naidu, Ratnala; Rahman, Nor-Afidah, A (June 2019). "Gutta percha". National Library Board, Singapore. Archived from the original on 2024-09-10. Retrieved 2024-09-10.{{cite web}}: CS1 maint: multiple names: authors list (link)
  2. ^ B.K. Sharma, Industrial Chemistry, p. 1117, Krishna Prakashan Media, 1991 ISBN 8187224991
  3. ^ أ ب Alamgir, A. N. M. (23 June 2018). Therapeutic Use of Medicinal Plants and their Extracts: Volume 2: Phytochemistry and Bioactive Compounds (in الإنجليزية). Springer. p. 183. ISBN 978-3-319-92387-1.
  4. ^ Text Book of Endodontics (in الإنجليزية). Elsevier India. 2009. p. 186. ISBN 978-81-312-2181-5.
  5. ^ أ ب Harvey Wickes Felter and John Uri Lloyd. "Gutta-Percha-: An Untold Story. Prakesh et al. ~2001 Endodontology". King's American Dispensatory.
  6. ^ أ ب ت Bill Burns, The Gutta Percha Company, atlantic-cable.com, accessed 6 October 2010.
  7. ^ Tully, John (2011). The Devil's Milk. NYU Press.
  8. ^ أ ب Manappallil, John J. (30 November 2015). Basic Dental Materials (in الإنجليزية). JP Medical Ltd. p. 219. ISBN 978-93-5250-048-2.
  9. ^ Aitken, Frédéric; Foulc, Jean-Numa (2019). "1". From deep sea to laboratory. 1 : the first explorations of the deep sea by H.M.S. Challenger (1872-1876). London, UK: ISTE-WILEY. pp. 16–38. ISBN 9781786303745.
  10. ^ Tully, John (2009). "A Victorian Ecological Disaster: Imperialism, the Telegraph, and Gutta-Percha". Journal of World History. 20 (4): 559–579. doi:10.1353/jwh.0.0088. S2CID 144216751. قالب:Project MUSE.
  11. ^ The Atlantic Telegraph: Its History, from the Commencement of the Undertaking in 1854, to the Sailing of the "Great Eastern" in 1866. Bacon and Company. 1866. p. 108.
  12. ^ Schlesinger, Henry (2010). The battery how portable power sparked a technological revolution. New York: HarperCollins e-books. ISBN 9780061985294.
  13. ^ Prescott, George Bartlett (1881). Electricity and the Electric Telegraph (in الإنجليزية). D. Appleton. p. 956.
  14. ^ Curtis, H.L.. Dielectric Constant, Power Factor and Resistivity of Rubber and Gutta_Percha. United States N.I.S.T.. Archived from the original. You must specify the date the archive was made using the |archivedate= parameter. https://nvlpubs.nist.gov/nistpubs/nbstechnologic/nbstechnologicpaperT299.pdf. 
  15. ^ Aitken, Frederic; Foulc, Jean-Numa (30 April 2019). From Deep Sea to Laboratory 1: The First Explorations of the Deep Sea by H.M.S. Challenger (1872-1876) (in الإنجليزية). John Wiley & Sons. p. 20. ISBN 978-1-78630-374-5.
  16. ^ Great Exhibition (1851) Reports by the Juries on the Subjects in the Thirty Classes Into which the Exhibition was Divided: Reports, classes XXIX, XXX (in الإنجليزية). Vol. 4. London): Spicer Brothers. 1852. p. 1740.
  17. ^ Burke, James (8 September 2003). Circles: Fifty Round Trips Through History Technology Science Culture (in الإنجليزية). Simon and Schuster. p. 86. ISBN 978-0-7432-4976-8.
  18. ^ Loeffel-Atkins, Bernadette (1 April 2012). Widow's Weeds and Weeping Veils: Mourning Rituals in 19th Century America (in الإنجليزية). Gettysburg Publishing. p. 19. ISBN 978-1-7346276-1-9.
  19. ^ Green, Michael S. (2010). Politics and America in Crisis: The Coming of the Civil War. Santa Barbara, CA: ABC-CLIO. p. 94. ISBN 978-0-313-08174-3 – via Google Books.
  20. ^ McInnes, Paul (16 June 2022). "'Faster, sportier, fairer': are football's proposed new law trials a good idea?". The Guardian. Retrieved 1 October 2023.
  21. ^ Bythell, Shaun (2022). Confessions of a Bookseller. Boston: Godine. p. 51. ISBN 978-1-56792-722-1.
  22. ^ Moyer, Susan Louise (1991), Silk Painting: The Artist's Guide to Gutta and Wax Resist Techniques, Watson-Guptill Publications, ISBN 0823048284 
  23. ^ Ball, Kazz; Janitch, Valerie (1993), Hand Painted Textiles for the Home, David & Charles Publishers, p. 94, ISBN 0715301578 
  24. ^ Yee, Fulton S.; Marlin, Jay; Krakow, Alvin Arlen; Gron, Poul (1977). "Three-dimensional obturation of the root canal using injection-molded, thermoplasticized dental gutta-percha". Journal of Endodontics. 3 (5): 168–174. doi:10.1016/s0099-2399(77)80091-5. PMID 266025.

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