Latex

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This article is about the polymer. For the document preparation system and markup language, see LaTeX. For other uses, see Latex (disambiguation).
rubber
production

Latex is an emulsion (stable dispersion) of polymer microparticles in water.[1] Latexes are found in nature, but synthetic latexes are common as well.

In nature, latex is found as a

plant sap
; it is a distinct substance, separately produced, and with different functions.

The word latex is also used to refer to natural latex

rubber, particularly non-vulcanized rubber. Such is the case in products like latex gloves, latex condoms, latex clothing, and balloons
.

IUPAC definition for latex

Biology

Articulated laticifers

The

rubber trees (Para rubber tree, members of the family Euphorbiaceae, members of the mulberry and fig family, such as the Panama rubber tree Castilla elastica), and members of the family Asteraceae. For instance, Parthenium argentatum the guayule plant, is in the tribe Heliantheae; 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.[6]

Non-articulated laticifers

In the

milkweed and 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 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, leaves, and sometimes the fruits. It is particularly noticeable in the cortical tissues. Latex is usually exuded as a white liquid, but is some cases it can be clear, yellow or red, as in Cannabaceae.[2]

Productive species

Latex is produced by 20,000

milk-caps. This suggests it is the product of convergent evolution and has been selected for on many separate occasions.[2]

Defense function

Rubber tapping latex

Latex functions to protect the plant from herbivores. The idea was first proposed in 1887 by Joseph F. James, who noted that latex of milkweed

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.[8]

Evidence showing this defense function include the finding that

milkweed) kills by trapping 30% of newly hatched monarch butterfly caterpillars.[2]

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 "antinutritive."

Latex is actively moved to the area of injury; in the case of Cryptostegia grandiflora, latex more than 70 cm from the site of injury is mobilized.[2] The large hydrostatic pressure in this vine enables an extremely high flow rate of latex. In a 1935 report the botanist Catherine M. Bangham observed that "piercing the fruit stalk of Cryptostegia grandiflora produced a jet of latex over a meter long, and maintained [this jet] for several seconds."[9]

The clotting property of latex is functional in this defense since it limits wastage and its stickiness traps insects and their mouthparts.[2]

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".[2]

Applications

Opium poppy exuding fresh latex from a cut

The latex of many species can be processed to produce many materials.

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.[11] This latex is used to make many other products including mattresses,[12][13] gloves, swim caps, condoms, catheters and balloons.[citation needed]

Opium and opiates

Dried latex from the

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.[citation needed
]

Clothing

Main article: Latex clothing

Latex is used in many types of clothing. Worn on the body (or applied directly by painting), it tends to be skin-tight, producing a "second skin" effect.[14]

Industrial and biological applications of synthetic latexes

Synthetic latexes are used in

glues because they solidify by 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.[15]

Allergic reactions

Main article: Latex allergy

Some people only experience a

eczema, contact dermatitis or developing a rash.[16]

Others have a serious

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.[18]

Microbial degradation

Several species of the

microbe genera Actinomycetes, Streptomyces, Nocardia, Micromonospora, and Actinoplanes are capable of consuming rubber latex.[19] However, the rate of biodegradation is slow, and the growth of bacteria utilizing rubber as a sole carbon source is also slow.[20]

See also

References

  1. S2CID 96720306
    .
  2. ^
    doi:10.1146/annurev.ecolsys.110308.120307
    .
  3. S2CID 40056337
    .
  4. ^ Harper, Douglas. "latex". Online Etymology Dictionary.
  5. Perseus Project
    .
  6. ^ "Taraxacum kok-saghyz". Pfaf.org. Archived from the original on 2014-03-20. Retrieved 2013-03-21.
  7. S2CID 44594197
    .
  8. JSTOR 2451222
    .
  9. ISBN 978-0124314269.{{cite book}}: CS1 maint: location (link
    )
  10. ISBN 978-0-8165-2821-9
    .
  11. OCLC 28534889
    .
  12. ^ Liman, Stacy (26 June 2020). "Latex Mattresses: The Best Latex Mattress Guide". Retrieved 17 August 2020.
  13. ^ Yurkovich, Dror. "Dunlop latex vs. Talalay latex". Getha. Archived from the original on 2021-04-13. Retrieved 2021-04-22.
  14. OCLC 1262726608.{{cite book}}: CS1 maint: location missing publisher (link) CS1 maint: others (link
    )
  15. ISSN 0269-4727
    .
  16. ^ "Latex Allergy | Causes, Symptoms & Treatment". ACAAI Public Website. Retrieved 2019-03-24.
  17. ISBN 9781859573815
    . Retrieved 8 May 2018 – via Google Books.
  18. ^ "Latex allergy - Symptoms and causes". mayoclinic.com. Archived from the original on 7 October 2013. Retrieved 8 May 2018.
  19. PMID 10966376
    .
  20. PMID 15932971
    .

External links

  • Media related to latex at Wikimedia Commons
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