latex
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Latex is a stable dispersion (
emulsion An emulsion is a mixture of two or more liquids that are normally Miscibility, immiscible (unmixable or unblendable) owing to liquid-liquid phase separation. Emulsions are part of a more general class of two-phase systems of matter called colloid ...

emulsion
) of
polymer A polymer (; Greek ''wikt:poly-, poly-'', "many" + ''wikt:-mer, -mer'', "part") is a Chemical substance, substance or material consisting of very large molecules, or macromolecules, composed of many Repeat unit, repeating subunits. Due to their ...

polymer
microparticles in water. Latexes are found in
nature Nature, in the broadest sense, is the natural, physical, material world or universe The universe ( la, universus) is all of space and time and their contents, including planets, stars, galaxies, and all other forms of matter and ...

nature
, but synthetic latexes are common as well. Latex as found in nature is a milky
fluid In physics, a fluid is a substance that continually Deformation (mechanics), deforms (flows) under an applied shear stress, or external force. Fluids are a Phase (matter), phase of matter and include liquids, Gas, gases and Plasma (physics), pl ...
found in 10% of all flowering plants (
angiosperms Flowering plants include multiple members of the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλά ...
). It is a complex emulsion that coagulates on exposure to air, consisting of
protein Proteins are large s and s that comprise one or more long chains of . Proteins perform a vast array of functions within organisms, including , , , providing and , and from one location to another. Proteins differ from one another primarily ...

protein
s,
alkaloid Alkaloids are a class of base (chemistry), basic, natural product, naturally occurring organic compounds that contain at least one nitrogen atom. This group also includes some related compounds with neutral and even weakly acidic properties. Som ...
s,
starch Starch or amylum is a consisting of numerous units joined by s. This is produced by most green s for energy storage. Worldwide, it is the most common carbohydrate in human diets, and is contained in large amounts in s like , es, (corn), , ...
es,
sugar Sugar is the generic name for , soluble s, many of which are used in food. Simple sugars, also called s, include , , and . Compound sugars, also called s or double sugars, are molecules made of two monosaccharides joined by a . Common examp ...

sugar
s,
oil An oil is any nonpolar chemical substance A chemical substance is a form of matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. All everyday objects that can b ...
s,
tannin Tannins (or tannoids) are a class of , ic s that bind to and s and various other organic compounds including s and s. The term ''tannin'' (from ''tanner'', from ''tannāre'', from ''tannum'', ) refers to the use of oak and other bark ...
s,
resin In polymer chemistry and materials science, resin is a solid or highly Viscosity, viscous substance of plant or synthetic origin that is typically convertible into polymers. Resins are usually mixtures of organic compounds. This article focus ...

resin
s, and gums. It is usually exuded after tissue injury. In most plants, latex is white, but some have yellow, orange, or scarlet latex. Since the 17th century, latex has been used as a term for the fluid substance in plants, deriving from the
Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known as Latium. Through the power of the Roman Republic, it became the dominant la ...

Latin
word for "liquid". It serves mainly as
defense Defense or defence may refer to: Tactical, martial, and political acts or groups * Defense (military) A military, also known collectively as armed forces, is a heavily armed, highly organized force primarily intended for warfare. It is ty ...
against
herbivorous A herbivore is an animal Animals (also called Metazoa) are multicellular eukaryotic organisms that form the Kingdom (biology), biological kingdom Animalia. With few exceptions, animals Heterotroph, consume organic material, Cellular r ...

herbivorous
insect Insects (from Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known as Latium. Through the power of the Rom ...

insect
s. Latex is not to be confused with
plant sap SAP SE () is a German multinational software corporation based in Walldorf, Baden-Württemberg Baden-Württemberg (; ) is a States of Germany, state (''Land'') in southwest Germany, east of the Rhine, which forms the southern part of Ge ...

plant sap
; it is a distinct substance, separately produced, and with separate functions. The word latex is also used to refer to natural latex
rubber Rubber, also called India rubber, latex, Amazonian rubber, ''caucho'', or ''caoutchouc'', as initially produced, consists of polymer A polymer (; Greek ''wikt:poly-, poly-'', "many" + ''wikt:-mer, -mer'', "part") is a Chemical substance, ...

rubber
, particularly non-
vulcanized Vulcanization (British: Vulcanisation) refers to a range of processes for hardening rubbers. The term originally referred exclusively to the treatment of natural rubber with sulfur, which remains the most common practice. It has also grown to i ...

vulcanized
rubber. Such is the case in products like latex
glove A glove is a garment A kanga, worn throughout the African Great Lakes region Clothing (also known as clothes, apparel and attire) are items worn on the body. Clothing is typically made of fabrics or textile A textile is a flexi ...

glove
s, latex
condom A condom is a sheath-shaped Barrier contraception, barrier device used during sexual intercourse to reduce the probability of pregnancy or a Sexually transmitted disease, sexually transmitted infection (STI). There are both male and female cond ...

condom
s and
latex clothing Latex rubber is used in many types of clothing. Rubber has traditionally been used in protective clothing, including gas masks and Wellington boots. Rubber is now generally being replaced in these application by plastics. Mackintoshes have tradit ...
.


Biology


Articulated laticifers

The
cells Cell most often refers to: * Cell (biology), the functional basic unit of life Cell may also refer to: Closed spaces * Monastic cell, a small room, hut, or cave in which a monk or religious recluse lives * Prison cell, a room used to hold peopl ...
(
laticiferA laticifer is a type of elongated secretory cell found in the leaves A leaf (plural leaves) is the principal lateral appendage of the vascular plant plant stem, stem, usually borne above ground and specialized for photosynthesis. The leave ...
s) in which latex is found make up the laticiferous system, which can form in two very different ways. In many plants, the laticiferous system is formed from rows of cells laid down in the
meristem The meristem is a type of tissue Tissue may refer to: Biology * Tissue (biology), an ensemble of similar cells that together carry out a specific function * ''Triphosa haesitata'', a species of geometer moth found in North America * ''Triphosa du ...
of the
stem Stem or STEM may refer to: Biology * Plant stem '' has lost its leaves, but is producing adventitious roots from the nodes. A stem is one of two main structural axes of a vascular plant, the other being the root In vascular plants, the roo ...

stem
or
root In vascular plant Vascular plants (from Latin ''vasculum'': duct), also known as Tracheophyta (the tracheophytes , from Greek τραχεῖα ἀρτηρία ''trācheia artēria'' 'windpipe' + φυτά ''phutá'' 'plants'), form a large group ...

root
. The
cell wall A cell wall is a structural layer surrounding some types of cells, just outside the cell membrane cell membrane vs. Prokaryotes The cell membrane (also known as the plasma membrane (PM) or cytoplasmic membrane, and historically referred to a ...
s between these cells are dissolved so that continuous tubes, called latex vessels, are formed. Since these vessels are made of many cells, they are known as ''articulated laticifers''. This method of formation is found in the poppy family and in the
rubber Rubber, also called India rubber, latex, Amazonian rubber, ''caucho'', or ''caoutchouc'', as initially produced, consists of polymer A polymer (; Greek ''wikt:poly-, poly-'', "many" + ''wikt:-mer, -mer'', "part") is a Chemical substance, ...

rubber
trees (
Para rubber tree ''Hevea brasiliensis'', the Pará rubber tree, ''sharinga'' tree, seringueira, or, most commonly, the rubber tree or rubber plant, is a flowering plant The flowering plants, also known as Angiospermae (), or Magnoliophyta (), are the most dive ...
, members of the family
Euphorbiaceae The Euphorbiaceae, the spurge ''Euphorbia'' is a very large and diverse genus Genus (plural genera) is a taxonomic rank Taxonomy (general) is the practice and science of classification of things or concepts, including the principles that ...

Euphorbiaceae
, members of the , such as the Panama rubber tree ''
Castilla elastica ''Castilla elastica'', the Panama rubber tree, is a tree native to the Tropics, tropical areas of Mexico, Central America, and northern South America. It was the principal source of latex among the Mesoamerican peoples in Pre-Columbian era, pre-Co ...
''), and members of the family
Asteraceae The family (biology), family Asteraceae, alternatively Compositae, consists of over 32,000 known species of flowering plants in over 1,900 genera within the Order (biology), order Asterales. Commonly referred to as the aster, daisy, composite, or ...

Asteraceae
. For instance, '' Parthenium argentatum'' the guayule plant, is in the tribe
Heliantheae The Heliantheae (sometimes called the sunflower tribe) are the third-largest Tribe (biology), tribe in the sunflower family (Asteraceae). With some 190 genera and nearly 2500 recognized species, only the tribes Senecioneae and Astereae are larger ...
; other latex-bearing Asteraceae with articulated laticifers include members of the Cichorieae, a clade whose members produce latex, some of them in commercially interesting amounts. This includes ''Taraxacum kok-saghyz'', a species cultivated for latex production.


Non-articulated laticifers

In the Asclepiadaceae, milkweed and Euphorbiaceae, spurge families, on the other hand, the laticiferous system is formed quite differently. Early in the development of the seedling, latex cells differentiate, and as the plant grows these latex cells grow into a branching system extending throughout the plant. In many Euphorbiaceae, euphorbs, the entire structure is made from a single cell – this type of system is known as a ''non-articulated laticifer'', to distinguish it from the multi-cellular structures discussed above. In the mature plant, the entire laticiferous system is descended from a single cell or group of cells present in the embryo. The laticiferous system is present in all parts of the mature plant, including roots, stems, leaf, leaves, and sometimes the fruits. It is particularly noticeable in the Cortex (botany), cortical tissues. Latex is usually exuded as a white liquid, but is some cases it can be clear, yellow or red, as in Cannabaceae.


Productive species

Latex is produced by 20,000 flowering plant species from over 40 family (biology), families. These include both dicotyledonous, dicots and monocotyledonous, monocots. Latex has been found in 14 percent of tropical plant species, as well as six percent of temperate plant species. Several members of the fungal kingdom also produce latex upon injury, such as ''Lactarius deliciosus'' and other lactarius, milk-caps. This suggests it is the product of convergent evolution and has been selected for on many separate occasions.


Defense function

Latex functions to protect the plant from herbivores. The idea was first proposed in 1887 by Joseph F. James, who noted that latex
carries with it at the same time such disagreeable properties that it becomes a better protection to the plant from enemies than all the thorns, prickles, or hairs that could be provided. In this plant, so copious and so distasteful has the sap become that it serves a most important purpose in its economy.
Evidence showing this defense function include the finding that slugs will eat leaves drained of their latex but not intact ones, that many insects sever the veins carrying latex before they feed, and that the latex of ''Asclepias humistrata'' (sandhill milkweed) kills by trapping 30% of newly hatched monarch butterfly caterpillars. Other evidence is that latex contains 50–1000× higher concentrations of defense substances than other plant tissues. These toxins include ones that are also toxic to the plant and consist of a diverse range of chemicals that are either poisonous or "Antinutrient, antinutritive". Latex is actively moved to the area of injury; in the case of ''Cryptostegia grandiflora'', this can be more than 70 cm. The clotting property of latex is functional in this defense since it limits wastage and its stickiness traps insects and their mouthparts. While there exist other explanations for the existence of latex including storage and movement of plant nutrients, waste, and maintenance of water balance that "[e]ssentially none of these functions remain credible and none have any empirical support".


Applications

The latex of many species can be processed to produce many materials. * Balatá and gutta percha latex contain an inelastic polymer related to rubber. * Chicle and Dyera costulata, jelutong tree latex was used in chewing gum.


Personal and healthcare products

Natural rubber is the most important product obtained from latex; more than 12,000 plant species yield latex containing rubber, though in the vast majority of those species the rubber is not suitable for commercial use. This latex is used to make many other products including mattresses,
glove A glove is a garment A kanga, worn throughout the African Great Lakes region Clothing (also known as clothes, apparel and attire) are items worn on the body. Clothing is typically made of fabrics or textile A textile is a flexi ...

glove
s, swim caps,
condom A condom is a sheath-shaped Barrier contraception, barrier device used during sexual intercourse to reduce the probability of pregnancy or a Sexually transmitted disease, sexually transmitted infection (STI). There are both male and female cond ...

condom
s, catheters and balloons.


Opium and opiates

Dried latex from the Papaver somniferum, opium poppy is called opium, the source of several useful analgesic
alkaloid Alkaloids are a class of base (chemistry), basic, natural product, naturally occurring organic compounds that contain at least one nitrogen atom. This group also includes some related compounds with neutral and even weakly acidic properties. Som ...
s such as codeine, thebaine, and morphine, the latter two of which can then further be used in the synthesis and manufacture of other (typically stronger) opioids for medicinal use, and of heroin for the illegal drug trade. The opium poppy is also the source of medically useful non-analgesic alkaloids, such as papaverine and noscapine.


Clothing

Latex is used in many types of clothing. Worn on the body (or applied directly by painting), it tends to be skin-tight garment, skin-tight, producing a "second skin" effect.


Industrial and biological applications from synthetic latexes

Synthetic latexes are used in coatings (e.g., latex paint) and glues because they solidify by Coalescence (chemistry), coalescence of the polymer particles as the water evaporates. These synthetic latexes therefore can form films without releasing potentially toxic organic solvents in the environment. Other uses include cement additives and to conceal information on scratchcards. Latex, usually styrene-based, is also used in immunoassays.


Allergic reactions

Some people only experience a Allergy, mild allergy when exposed to latex, like eczema, Contact dermatitis, contact dermatitis or developing a rash. Others have a serious latex allergy, and exposure to latex products such as latex gloves can cause anaphylactic shock. Guayule latex has only 2% of the levels of protein found in ''Hevea'' latexes, and is being researched as a lower-allergen substitute. Additionally, chemical processes may be employed to reduce the amount of antibody generator, antigenic protein in ''Hevea'' latex, yielding alternative materials such as Vytex Natural Rubber Latex which provide significantly reduced exposure to latex allergens. About half of people with spina bifida are also allergic to natural latex rubber, as well as people who have had multiple surgeries, and people who have had prolonged exposure to natural latex.


Microbial degradation

Several species of the microbe genera ''Actinobacteria, Actinomycetes'', ''Streptomyces'', ''Nocardia'', ''Micromonospora'', and ''Actinoplanes'' are capable of consuming rubber latex. However, the rate of biodegradation is slow, and the growth of bacteria utilizing rubber as a sole carbon source is also slow.


See also

*Latex clothing *Natural rubber *


References


Footnotes


Notes


External links

* {{Authority control Materials Sculpture materials Rubber