In polymer chemistry
and materials science
, resin is a solid
or highly viscous
substance of plant or synthetic origin that is typically convertible into polymer
s. Resins are usually mixtures of organic compound
s. This article focuses on naturally occurring resins.
Plants secrete resins for their protective benefits in response to injury. The resin protects the plant from insects and pathogens. Resins confound a wide range of herbivores, insects, and pathogens, while the volatile phenolic compounds
may attract benefactors such as parasitoid
s or predators of the herbivores that attack the plant.
Most plant resins are composed of terpenes
. Specific components are alpha-pinene
, delta-3 carene
, and sabinene
, the monocyclic terpenes limonene
, and smaller amounts of the tricyclic sesquiterpene
, and delta-cadinene
. Some resins also contain a high proportion of resin acid
s on the other hand are less volatile and consist of diterpenes among other compounds.
Examples of plant resins include amber
, Balm of Gilead
, Canada balsam
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
from ''Boswellia sacra
from ''Ferula gummosa
'', gum guaiacum
from the lignum vitae
trees of the genus ''Guaiacum
'', kauri gum
from trees of ''Agathis australis
(Cannabis resin) from ''Cannabis indica
from mediterranean species of ''Cistus
'', mastic (plant resin)
from the mastic tree ''Pistacia lentiscus
from shrubs of ''Commiphora
resin from ''Tetraclinis articulata
'', the national tree of Malta, styrax
(a Benzoin resin
from various ''Styrax
'' species) and spinifex resin
from Australian grasses.
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
is placed on it.
and the kauri gum
of New Zealand are also procured in a semi-fossil condition.
is a solidified resin from which the volatile terpene
s 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 oil
, 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 acid
s. Related to the terpenes, resin acid is oxidized
terpenes. Resin acids dissolve in alkali
s to form resin soap
s, from which the resin acids are regenerated upon treatment with acids. Examples of resin acids are abietic acid
(sylvic acid), C20
, plicatic acid
contained in cedar, and pimaric acid
, a constituent of galipot
resin. Abietic acid can also be extracted from rosin by means of hot alcohol. Pimaric acid closely resembles abietic acid into which it passes when distilled in a vacuum; it has been supposed to consist of three isomers.
Rosin is obtained from pine
s and some other plant
s, mostly conifers
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. Propolis
, consisting largely of resins collected from plants such as poplars
s, is used by honey bee
s to seal small gaps in their hives, while larger gaps are filled with beeswax.
Petroleum- and insect-derived resins
is an example of an insect-derived resin.
and Utah resin are petroleum bitumen
History and etymology
Human use of plant resins has a very long history that was documented in ancient Greece
, in ancient Rome by Pliny the Elder
, and especially in the resins known as frankincense
, prized in ancient Egypt
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 ''rhētínē'' "resin of the pine", of unknown earlier origin, though probably non-Indo-European
The word "resin" has been applied in the modern world to nearly any component of a liquid that will set into a hard lacquer
-like finish. An example is nail polish. Certain "casting resins" and synthetic resin
s (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 resin
s. Several natural resins are used as ingredients in perfumes, e.g., balsams of Peru and tolu, elemi, styrax, and certain turpentines.
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.
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.
thumb|Lumps of dried frankincense resin
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.
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.
* Resin extraction – method of harvesting resin from trees
* Balsam of Peru – a balsam used in food and drink for flavoring, in perfumes and toiletries for fragrance, and in medicine and pharmaceutical items.
* Mastic (plant resin) – resin from the Pistacia lentiscus tree
* Pitch (resin)
* Kino (gum) – a plant gum similar to resin
* Biodegradable – plant resins are naturally biodegradable in many circumstances.
* Resin casting – casting with a resin, usually using a synthetic not a natural resin.
* Polyresin – a hard, synthetic resin for casting in molds
Category:Non-timber forest products