Resin

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Insect trapped in resin Resin with insect (aka).jpg
Insect trapped in resin
Cedar of Lebanon cone showing flecks of resin as used in the mummification of Egyptian Pharaohs Cedar of Lebanon cone.JPG
Cedar of Lebanon cone showing flecks of resin as used in the mummification of Egyptian Pharaohs

In polymer chemistry and materials science, a resin is a solid or highly viscous substance of plant or synthetic origin that is typically convertible into polymers. [1] Resins are usually mixtures of organic compounds. This article focuses mainly on naturally occurring resins.

Contents

Plants secrete resins for their protective benefits in response to injury. Resins protect plants from insects and pathogens. [2] Resins confound a wide range of herbivores, insects, and pathogens, while the volatile phenolic compounds may attract benefactors such as parasitoids or predators of the herbivores that attack the plant. [3]

Composition

Most plant resins are composed of terpenes. Specific components are alpha-pinene, beta-pinene, delta-3 carene, and sabinene, the monocyclic terpenes limonene and terpinolene, and smaller amounts of the tricyclic sesquiterpenes, longifolene, caryophyllene, and delta-cadinene. Some resins also contain a high proportion of resin acids. Rosins on the other hand are less volatile and consist of diterpenes among other compounds.[ citation needed ]

Examples

Examples of plant resins include amber, Balm of Gilead, balsam, Canada balsam, copal from trees of Protium copal and Hymenaea courbaril , dammar gum from trees of the family Dipterocarpaceae, dragon's blood from the dragon trees ( Dracaena species), elemi, frankincense from Boswellia sacra , galbanum from Ferula gummosa , gum guaiacum from the lignum vitae trees of the genus Guaiacum , kauri gum from trees of Agathis australis , hashish (Cannabis resin) from Cannabis indica , labdanum from mediterranean species of Cistus , mastic (plant resin) from the mastic tree Pistacia lentiscus , myrrh from shrubs of Commiphora , sandarac resin from Tetraclinis articulata , the national tree of Malta, styrax (a Benzoin resin from various Styrax species) and spinifex resin from Australian grasses.

Amber is fossil resin (also called resinite) from coniferous and other tree species. Copal, kauri gum, dammar and other resins may also be found as subfossil deposits. Subfossil copal can be distinguished from genuine fossil amber because it becomes tacky when a drop of a solvent such as acetone or chloroform is placed on it. [4] African copal and the kauri gum of New Zealand are also procured in a semi-fossil condition.

Rosin

Extremely viscous resin extruding from the trunk of a mature Araucaria columnaris. Araucaria Resin.JPG
Extremely viscous resin extruding from the trunk of a mature Araucaria columnaris .

Rosin is a solidified resin from which the volatile terpenes have been removed by distillation. Typical rosin is a transparent or translucent mass, with a vitreous fracture and a faintly yellow or brown colour, non-odorous or having only a slight turpentine odour and taste. Rosin is insoluble in water, mostly soluble in alcohol, essential oils, ether, and hot fatty oils. Rosin softens and melts when heated and burns with a bright but smoky flame.

Rosin consists of a complex mixture of different substances including organic acids named the resin acids. Related to the terpenes, resin acid is oxidized terpenes. Resin acids dissolve in alkalis to form resin soaps, from which the resin acids are regenerated upon treatment with acids. Examples of resin acids are abietic acid (sylvic acid), C20H30O2, plicatic acid contained in cedar, and pimaric acid, C20H30O2, a constituent of galipot resin. Abietic acid can also be extracted from rosin by means of hot alcohol.

Rosin is obtained from pines and some other plants, mostly conifers. [5] Plant resins are generally produced as stem secretions, but in some Central and South American species of Dalechampia and Clusia they are produced as pollination rewards, and used by some stingless bee species in nest construction. [6] [7] Propolis, consisting largely of resins collected from plants such as poplars and conifers, is used by honey bees to seal small gaps in their hives, while larger gaps are filled with beeswax. [8]

Petroleum- and insect-derived resins

Shellac is an example of an insect-derived resin.

Asphaltite and Utah resin are petroleum bitumens.

History and etymology

The material dripping from an almond tree looks confusingly like resin, but actually is a gum or mucilage, and chemically very different. Resin on Almond tree.jpg
The material dripping from an almond tree looks confusingly like resin, but actually is a gum or mucilage, and chemically very different.

Human use of plant resins has a very long history that was documented in ancient Greece by Theophrastus, in ancient Rome by Pliny the Elder, and especially in the resins known as frankincense and myrrh, prized in ancient Egypt. [9] These were highly prized substances, and required as incense in some religious rites.

The word resin comes from French resine, from Latin resina "resin", which either derives from or is a cognate of the Greek ῥητίνηrhētínē "resin of the pine", of unknown earlier origin, though probably non-Indo-European. [10] [11]

The word "resin" has been applied in the modern world to nearly any component of a liquid that will set into a hard lacquer or enamel-like finish. An example is nail polish. Certain "casting resins" and synthetic resins (such as epoxy resin) have also been given the name "resin".

Some naturally-derived resins, when soft, are known as 'oleoresins', and when containing benzoic acid or cinnamic acid they are called balsams. Oleoresins are naturally-occurring mixtures of an oil and a resin; they can be extracted from various plants. Other resinous products in their natural condition are a mix with gum or mucilaginous substances and known as gum resins. Several natural resins are used as ingredients in perfumes, e.g., balsams of Peru and tolu, elemi, styrax, and certain turpentines. [5]

Non-resinous exudates

Other liquid compounds found inside plants or exuded by plants, such as sap, latex, or mucilage, are sometimes confused with resin but are not the same. Saps, in particular, serve a nutritive function that resins do not.

Resin of pine Resine.jpg
Resin of pine

Uses

Plant resins

Plant resins are valued for the production of varnishes, adhesives, and food glazing agents. They are also prized as raw materials for the synthesis of other organic compounds and provide constituents of incense and perfume. The oldest known use of plant resin comes from the late Middle Stone Age in Southern Africa where it was used as an adhesive for hafting stone tools. [12]

Lumps of dried frankincense resin Frankincense 2005-12-31.jpg
Lumps of dried frankincense resin
Caranna, a hard, brittle, resinous gum from species of Protium Protium Sp. MHNT.BOT.2016.24.54.jpg
Caranna, a hard, brittle, resinous gum from species of Protium

The hard transparent resins, such as the copals, dammars, mastic, and sandarac, are principally used for varnishes and adhesives, while the softer odoriferous oleo-resins (frankincense, elemi, turpentine, copaiba), and gum resins containing essential oils (ammoniacum, asafoetida, gamboge, myrrh, and scammony) are more used for therapeutic purposes, food and incense. The resin of the Aleppo Pine is used to flavour retsina, a Greek resinated wine. [13]

Animal resins

While animal resins are not as common as either plant or synthetic resins some animal resins like lac (obtained from Kerria lacca ) are used for applications like sealing wax in India, [14] and lacquerware in Sri Lanka.[ citation needed ]

Synthetic resins

Many materials are produced via the conversion of synthetic resins to solids. Important examples are bisphenol A diglycidyl ether, which is a resin converted to epoxy glue upon the addition of a hardener. Silicones are often prepared from silicone resins via room temperature vulcanization. Alkyd resins are used in paints and varnishes and harden or cure by exposure to oxygen in the air. [15]

See also

Related Research Articles

<span class="mw-page-title-main">Myrrh</span> Aromatic resin from the Commiphora myrrha tree

Myrrh is a gum-resin extracted from a few small, thorny tree species of the Commiphora genus, belonging to the Burseraceae family. Myrrh resin has been used throughout history in medicine, perfumery, and incenses. Myrrh mixed with posca or wine was widely used in many ancient cultures to produce pleasurable feelings and as an anti-inflammatory and analgesic.

<span class="mw-page-title-main">Varnish</span> Transparent hard protective finish or film

Varnish is a clear transparent hard protective coating or film. It is not to be confused with wood stain. It usually has a yellowish shade due to the manufacturing process and materials used, but it may also be pigmented as desired. It is sold commercially in various shades.

<span class="mw-page-title-main">Frankincense</span> Aromatic resin from Boswellia trees

Frankincense, also known as olibanum, is an aromatic resin used in incense and perfumes, obtained from trees of the genus Boswellia in the family Burseraceae. The word is from Old French franc encens. There are several species of Boswellia that produce true frankincense: Boswellia sacra, B. frereana, B. serrata, and B. papyrifera. Resin from each is available in various grades, which depends on the time of harvesting. The resin is hand-sorted for quality.

<span class="mw-page-title-main">Rosin</span> Solid form of resin

Rosin, also called colophony or Greek pitch, is a solid form of resin obtained from pines and some other plants, mostly conifers, produced by heating fresh liquid resin to vaporize the volatile liquid terpene components. It is semi-transparent and varies in color from yellow to black. At room temperature rosin is brittle, but it melts at stove-top temperature. It chiefly consists of various resin acids, especially abietic acid. The term colophony comes from colophonia resina, Latin for "resin from Colophon", an ancient Ionic city. It is an FDA approved food additive.

<span class="mw-page-title-main">Balsam</span> Index of plants with the same common name

Balsam is the resinous exudate which forms on certain kinds of trees and shrubs. Balsam owes its name to the biblical Balm of Gilead.

<span class="mw-page-title-main">Canada balsam</span> Turpentine made from the resin of the balsam fir tree

Canada balsam, also called Canada turpentine or balsam of fir, is the oleoresin of the balsam fir tree of boreal North America. The resin, dissolved in essential oils, is a viscous, sticky, colourless or yellowish liquid that turns to a transparent yellowish mass when the essential oils have been allowed to evaporate.

<span class="mw-page-title-main">Dammar gum</span> Tree resin obtained from the family Dipterocarpaceae

Dammar, also called dammar gum, or damar gum, is a resin obtained from the tree family Dipterocarpaceae in India and Southeast Asia, principally those of the genera Shorea or Hopea. The resin of some species of Canarium may also called dammar. Most is produced by tapping trees; however, some is collected in fossilised form on the ground. The gum varies in colour from clear to pale yellow, while the fossilised form is grey-brown. Dammar gum is a triterpenoid resin, containing many triterpenes and their oxidation products. Many of them are low molecular weight compounds, which easily oxidizes and photoxidizes.

<span class="mw-page-title-main">Onycha</span> Unknown biblical substance used in incense

Onycha, along with equal parts of stacte, galbanum, and frankincense, was one of the components of the consecrated Ketoret (incense) which appears in the Torah book of Exodus (Ex.30:34-36) and was used in Solomon's Temple in Jerusalem. This formula was to be incorporated as an incense, and was not to be duplicated for non-sacred use. What the onycha of antiquity actually was cannot be determined with certainty. The original Hebrew word used for this component of the ketoret was שחלת, shecheleth, which means "to roar; as a lion " or “peeling off by concussion of sound." Shecheleth is related to the Syriac shehelta which is translated as “a tear, distillation, or exudation.” In Aramaic, the root SHCHL signifies “retrieve.” When the Torah was translated into Greek the Greek word “onycha” ονυξ, which means "fingernail" or "claw," was substituted for shecheleth.

<i>Pinus roxburghii</i> Species of conifer

Pinus roxburghii, commonly known as chir pine or longleaf Indian pine, is a species of pine tree native to the Himalayas. It was named after William Roxburgh.

<i>Styrax</i> Genus of plants

Styrax is a genus of about 130 species of large shrubs or small trees in the family Styracaceae, mostly native to warm temperate to tropical regions of the Northern Hemisphere, with the majority in eastern and southeastern Asia, but also crossing the equator in South America. The resin obtained from the tree is called benzoin or storax.

<span class="mw-page-title-main">Benzoin (resin)</span> Balsamic resin from trees in genus Styrax

Benzoin or benjamin is a balsamic resin obtained from the bark of several species of trees in the genus Styrax. It is used in perfumes and some kinds of incense and as a flavoring and medicine. It is distinct from the chemical compound benzoin, which is ultimately derived chemically from benzoin resin; the primary active ingredient of benzoin resin is actually benzoic acid, not benzoin.

<span class="mw-page-title-main">Burseraceae</span> Family of flowering plants

The Burseraceae are a moderate-sized family of 17-19 genera and about 540 species of woody flowering plants. The actual numbers given in taxonomic sources differ according to taxonomic revision at the time of writing. The Burseraceae are also known as the torchwood family, the frankincense and myrrh family, or simply the incense tree family. The family includes both trees and shrubs; its species are native to tropical regions of Africa, Asia, Australasia, and the Americas.

<span class="mw-page-title-main">Storax balsam</span>

Storax, often commercially sold as styrax, is a natural resin isolated from the wounded bark of Liquidambar orientalis Mill. and Liquidambar styraciflua L. (Hamamelidaceae). It is distinct from benzoin, a similar resin obtained from the Styracaceae plant family.

Tall oil, also called liquid rosin or tallol, is a viscous yellow-black odorous liquid obtained as a by-product of the kraft process of wood pulp manufacture when pulping mainly coniferous trees. The name originated as an anglicization of the Swedish tallolja. Tall oil is the third largest chemical by-product in a kraft mill after lignin and hemicellulose; the yield of crude tall oil from the process is in the range of 30–50 kg / ton pulp. It may contribute to 1.0–1.5% of the mill's revenue if not used internally.

<span class="mw-page-title-main">Naval stores industry</span>

The naval stores industry produces and markets products derived from the oleoresin of pine trees, including rosin, tall oil, pine oil, and turpentine. It does this by collecting and processing organic forest products refined from slash pine and longleaf pine trees. The naval stores industry was associated with the maintenance of the wooden ships and sailing tackle of pre-20th century navies, which were caulked and waterproofed using the pitch of the pine tree.

<span class="mw-page-title-main">Kauri gum</span> Resin

Kauri gum is resin from kauri trees, which historically had several important industrial uses. It can also be used to make crafts such as jewellery. Kauri forests once covered much of the North Island of New Zealand, before early settlers caused the forests to retreat, causing several areas to revert to weeds, scrubs, and swamps. Even afterwards, ancient kauri fields and the remaining forests continued to provide a source for the gum. Between 1820 and 1900, over 90% of Kauri forests were logged or burnt by Europeans.

<span class="mw-page-title-main">Stacte</span> Unknown biblical substance used in incense

Stacte and nataph are names used for one component of the Solomon's Temple incense, the Ketoret, specified in the Book of Exodus. Variously translated to the Greek term or to an unspecified "gum resin" or similar, it was to be mixed in equal parts with onycha, galbanum and mixed with pure frankincense and they were to "beat some of it very small" for burning on the altar of the tabernacle.

Gum copal is a resin produced by the sap of forest tree in the genus Daniellia. Due to common impurities and differences in regions, gum copal ranges in color from black to yellow to white. Gum copal, along with ivory and slaves, was a significant export from East Africa in the 19th century. It can have an appearance similar to amber and may be mistaken for it. Unlike amber, gum copal is usually only 100–1,000 years old and it has not yet fossilized.

<span class="mw-page-title-main">Levopimaric acid</span> Chemical compound

Levopimaric acid is an abietane-type of diterpene resin acid. It is a major constituent of pine oleoresin with the chemical formula of C20H30O2. In general, the abietene types of diterpene resin acid have various biological activities, such as antibacterial, cardiovascular and antioxidant. Levopimaric acid accounts for about 18 to 25% of pine oleoresin. The production of oleoresin by conifer species is an important component of the defense response against insect attack and fungal pathogen infection.

The incense offering, a blend of aromatic substances that exhale perfume during combustion, usually consisting of spices and gums burnt as an act of worship, occupied a prominent position in the sacrificial legislation of the ancient Hebrews.

References

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