gutta-percha

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gutta-percha

(gŭt`ə-pûr`chə), natural latexlatex,
emulsion of a polymer (e.g., rubber) in water (see colloid). Natural latexes are produced by a number of plants, are usually white in color, and often contain, in addition to rubber, various gums, oils, and waxes.
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 obtained from Palaquium gutta and several other evergreen trees of East Asia. The latex, collected by felling or girdling the tree, is allowed to coagulate and is then washed, purified, and molded into bricks for shipping. Like caoutchouccaoutchouc
, natural rubber obtained as a latex from various tropical plants, e.g., the Pará rubber tree. It is much more elastic than balata or gutta-percha. It is the most familiar and widely used of the natural rubbers.
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, gutta-percha is a polyterpene, i.e., a polymer of isoprene (see rubberrubber,
any solid substance that upon vulcanization becomes elastic; the term includes natural rubber (caoutchouc) and synthetic rubber. The term elastomer is sometimes used to designate synthetic rubber only and is sometimes extended to include caoutchouc as well.
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), but, unlike caoutchouc, it is not very elastic; the reason for the difference is that the polymer molecules in gutta-percha have a trans structure, whereas those of caoutchouc have a cis structure (see isomerisomer
, in chemistry, one of two or more compounds having the same molecular formula but different structures (arrangements of atoms in the molecule). Isomerism is the occurrence of such compounds. Isomerism was first recognized by J. J. Berzelius in 1827.
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). Gutta-percha is an excellent nonconductor and is often employed in insulating marine and underground cables. It is also used for golf-ball coverings, surgical appliances, and adhesives.

Gutta-Percha

 

a metabolic product of gutta-percha-yielding plants. The main constituent of gutta-percha (up to 90 percent)—high-molecular-weight trans-polyisoprene (gut-ta) with the empirical formula (C5H8)n—is an isomer of cis-polyisoprene, a hydrocarbon of natural rubber. The average molecular weight of gutta is about 50,000. Besides gutta, industrial gutta-percha contains resins, proteins, moisture, and other substances.

At room temperature, industrial gutta-percha is a solid skinlike substance that is white to yellowish-brown in color, with a density of 0.945–0.955 g/cm3, and an index of refraction nD20 = 1.523. Gutta-percha is resistant to the action of acids, including hydrochloric and hydrofluoric acids. When heated (50°-100° C), gutta-percha softens and becomes plastic and soluble in aromatic and chlorinated hydrocarbons. Its most valuable properties are waterproofness (moisture absorption in two years does not exceed 0.2 percent) and high electric insulation properties (dielectric permeability, 2.6; specific volume electric resistance 1012 ohm․m [1014 ohm •cm]). Like natural rubber, gutta-percha can be vulcanized with sulfur. The tensile strength of vulcanized gutta-percha is 17–30 meganewtons/m2 (170–300 kilograms-force/cm2) and the relative elongation, 500–550 percent.

Gutta-percha is used mainly as insulation for underwater cables and in the manufacture of acid-resistant and adhesive substances. The use of gutta-percha is declining because it is being replaced by synthetic trans-polyisoprene, trans-polychloroprene (so-called synthetic gutta-percha), and some other synthetic polymers.

REFERENCES

Voinovskii, A. B. Guttapercha. Moscow-Leningrad, 1951.
Spravochnik rezinshchika. Materialy rezinovogo proizvodstva. Moscow, 1971. Page 251.

gutta-percha

[¦gəd·ə′pər·chə]
(materials)
A leathery, thermoplastic substance consisting of gutta hydrocarbon with some resin obtained from the latex of certain Malaysian sapotaceous trees; used as insulation for submarine cables, and in golf balls and other products.

gutta-percha

1. any of several tropical trees of the sapotaceous genera Palaquium and Payena, esp Palaquium gutta
2. a whitish rubber substance derived from the coagulated milky latex of any of these trees: used in electrical insulation and dentistry
References in periodicals archive ?
To expand the antibacterial properties of guttapercha cones, the addition of several components has been proposed in their formulation, including polyvinilpyrrolidone-iodine, (18, 19) calcium hydroxide (CA[(OH).
A radiograph then taken with an increased vertical angulation revealed the presence of remaining root tips of both the central incisors left out during previous apicoectomy with retained guttapercha inside (Figure 2a).
In Group A, simulated root canals were filled with #50 conventional guttapercha (Dentsply-Maillefer, Ballaigues, Orbe, Switzerland), recording the time needed for filling each sample (mean: 7.
Annals of India rubber, guttapercha, celluloid and asbestos.
25% sodium hypochlorite after changing each file, rinsing with distilled water, wiping with paper tips (Dentsply-Maillefer[R]) and filling with guttapercha cones (Dentsply-Maillefer[R]) plus Top Seal[R] Dentsply[R] epoxy resin-based root canal sealer for Group 1 and Grossman[R] cement for Group 2, using a lateral condensation technique.
In the 1880s demand for telegraph cables--and hence for guttapercha --had levelled off and this had an impact on Sarawak's gutta percha exports (as shown in Figure 2), and also in a reduced state of trade across the Baram as a whole, as shown at Figure 1.
Obturation was done with warm vertical condensation technique using non standardised guttapercha cones and AH-26 sealer (Dentsply, De Trey, GmbH, Konstanz, Germany).
Adaptation of injected thermoplasticized guttapercha in absence of Dentinal Smear Layer Int Endo JOL:1993,26;87-92.
Still, for the period between 1870 and 1903, the guttapercha trade had contributed 12 percent of Sarawak's exports, compared with 15 percent from mining (with 51 percent from cultivation).
The most commonly used test is using a guttapercha stick heated until soft and glistens before applying to the vaseline-coated surface of the tooth under investigation for no more than 5 seconds.
The canals were filled with guttapercha points (Odous, Belo Horizonte, MG, Brazil) and Pulp Canal Sealer (Kerr Corp, Orange, Calif, USA) using the warm compaction technique.