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                        Natural rubber
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                           (Redirected from Rubber )

Navigatio n                "Rubber" and "India rubber" redirect here. For other uses, see Rubber (disambiguation) .
Main page                  This article is about the polymeric material natural rubber . For man-made rubber materials, see Synthetic rubber .
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Do nate to Wikipedia    Nat ural rubber, also called India Rubber or caout chouc, is an elastomer (an elastic
                        hydrocarbon polymer) that was originally derived from latex, a milky colloid produced by some
Interactio n            plants. The plants would be ‘tapped’, that is, an incision made into the bark of the tree and the
                        sticky, milk colored latex sap collected and refined into a usable rubber. The purified form of
Help
                        natural rubber is the chemical polyisoprene, which can also be produced synthetically. Natural
Abo ut Wikipedia
                        rubber is used extensively in many applications and products, as is synthetic rubber. It is
Co mmunity po rtal
                        normally very stretchy and flexible and extremely waterproof.
Recent changes
Co ntact Wikipedia                                    Co nt e nt s
                         1 Varieties
To o lbo x               2 Disco very o f co mmercial po tential
                         3 Pro perties
What links here
                         4 So lvents
Related changes
                         5 Chemical makeup
Uplo ad file
                             5.1 Elasticity
Special pages
                         6 Current so urces
Permanent link
                             6 .1 Cultivatio n                                                                                        Latex being collected from a tapped
Cite this page                                                                                                                        rubber tree
                              6 .2 Co llectio n
                              6 .3 Transpo rtatio n
Print/expo rt                      6 .3.1 Steel drums
                                   6 .3.2 ISO tanks
Create a bo o k
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Do wnlo ad as PDF              6 .3.3 Flexitank o r Flexibag inside 20 fo o t co ntainer
                               6 .3.4 Other metho ds
Printable versio n
                      7 Uses
                          7.1 Prehisto ric uses
Languages
                          7.2 Manufacturing
‫اﻟﻌرﺑﯾ ﺔ‬                  7.3 Textile applicatio ns
Беларуская            8 Vulcanizatio n
Български             9 Allergic reactio ns
                                                                                                                              Rubber tree plantation of Thailand
Català                10 See also                                                                                             (2011.8.7)
Česky                 11 References
Deutsch                   11.1 No tes
Ελληνικά                  11.2 So urces
Españo l                  11.3 Additio nal reso urces
Esperanto             12 Biblio graphy
Euskara               13 External links
‫ﻓﺎرﺳﯽ‬
Français             Varieties                                                                                                                                     [edit]
Galego
贛語                   The commercial source of natural rubber latex is the Pará rubber tree (Hevea brasiliensis), a member of the spurge family,
한국어                  Euphorbiaceae. This species is widely used because it responds to wounding by producing more latex.
िह दी                Other plants containing latex include gutta- percha (Palaquium gutta), [1] rubber fig (Ficus elastica), Panama rubber tree (Castilla elastica),
Hrvatski             spurges (Euphorbia spp.), lettuce, common dandelion (Taraxacum officinale), Russian dandelion (Taraxacum kok-saghyz ), Scorzonera (tau-
Ido                  saghyz), and guayule (Parthenium argentatum). Although these have not been major sources of rubber, Germany attempted to use some
Bahasa Indo nesia    of these during World War II when it was cut off from rubber supplies [citation needed]. These attempts were later supplanted by the
Íslenska             development of synthetic rubbers. To distinguish the tree- obtained version of natural rubber from the synthetic version, the term gum
Italiano             rubber is sometimes used.
‫ע ברית‬
ಕನಡ                  Discovery of commercial potential                                                                                                             [edit]
Ko ngo
                     The para rubber tree initially grew in South America. Charles Marie de La Condamine is credited with introducing samples of rubber to the
Lietuvių
                     Académie Royale des Sciences of France in 1736. [2] In 1751, he presented a paper by François Fresneau to the Académie (eventually
Magyar
                     published in 1755) which described many of the properties of rubber. This has been referred to as the first scientific paper on rubber.[2]
Nāhuatl
Nederlands           When samples of rubber first arrived in England, it was observed by Joseph Priestley, in 1770, that a piece of the material was extremely
日本語                  good for rubbing off pencil marks on paper, hence the name rubber . Later it slowly made its way around England.
no rsk (bo kmål)     South America remained the main source of the limited amounts of latex rubber that were used during much of the 19th century. In 1876,
no rsk (nyno rsk)    Henry Wickham gathered thousands of para rubber tree seeds from Braz il, and these were germinated in Kew Gardens , England. The
Po lski
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Po lski           seedlings were then sent to Ceylon (Sri Lanka), Indonesia, Singapore and British Malaya. Malaya (now Malaysia) was later to become
Po rtuguês        the biggest producer of rubber. About 100 years ago, the Congo Free State in Africa was also a significant source of natural rubber latex,
Ro mână           mostly gathered by forced labour. Liberia and Nigeria also started production of rubber.
Русский
                  In India, commercial cultivation of natural rubber was introduced by the British planters, although the experimental efforts to grow rubber on
Shqip
                  a commercial scale in India were initiated as early as 1873 at the Botanical Gardens, Calcutta. The first commercial Hevea plantations in
Sicilianu
                  India were established at Thattekadu in Kerala in 1902. In the 19th and early 20th century, it was often called "India rubber." In 2010,
    ංහල
                  India's natural rubber consumption stood at 978 thousand tons per year, with production at 893 thousand tons; the rest was imported with
Simple English
                  an import duty of 20%.
Slo venčina
Slo venščina
Српски / srpski
                  Properties                                                                                                                                     [edit]

Suo mi            Rubber exhibits unique physical and chemical properties. Rubber's stress- strain behavior exhibits
Svenska           the Mullins effect, the Payne effect, and is often modeled as hyperelastic. Rubber strain crystalliz es.
த
                  Owing to the presence of a double bond in each repeat unit , natural rubber is sensitive to oz one
    లుగు
                  cracking.
ไทย
Türkçe
                  Solvents                                                                                            [edit]
Українська
‫اردو‬              There are two main solvents for rubber: turpentine and naphtha (petroleum). The former has been in
Tiếng Việt        use since 1764 when François Fresnau made the discovery. Giovanni Fabbroni is credited with the
                                                                                                                                Rubber latex
West-Vlams        discovery of naphtha as a rubber solvent in 1779. Because rubber does not dissolve easily, the
‫יי ִדיש‬           material is finely divided by shredding prior to its immersion.
中文
                  An ammonia solution can be used to prevent the coagulation of raw latex while it is being transported from its collection site.

                  Chemical makeup                                                                                                                                [edit]

                  Latex is a natural polymer of isoprene (most often cis- 1,4- polyisoprene) – with a molecular weight of 100,000 to 1,000,000. Typically, a
                  small percentage (up to 5% of dry mass) of other materials, such as proteins, fatty acids, resins and inorganic materials (salts) are found
                  in natural rubber. Polyisoprene is also created synthetically, producing what is sometimes referred to as "synthetic natural rubber".
                  Some natural rubber sources called gutta- percha are composed of trans- 1,4- polyisoprene, a structural isomer which has similar, but not
                  identical, properties.
                  Natural rubber is an elastomer and a thermoplastic. However, it should be noted that once the rubber is vulcaniz ed, it will turn into a
                  thermoset. Most rubber in everyday use is vulcaniz ed to a point where it shares properties of both; i.e., if it is heated and cooled, it is
                  degraded but not destroyed.

                  Elasticity                                                                                                                                     [edit]

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In most elastic materials, such as metals used in springs, the elastic behavior is caused by bond distortions. When force is applied, bond
lengths deviate from the (minimum energy) equilibrium and strain energy is stored electrostatically. Rubber is often assumed to behave in
the same way, but it turns out this is a poor description. Rubber is a curious material because, unlike metals, strain energy is stored
thermally.
In its relaxed state, rubber consists of long, coiled- up polymer chains that are interlinked at a few points. Between a pair of links, each
monomer can rotate freely about its neighbour, thus giving each section of chain leeway to assume a large number of geometries, like a
very loose rope attached to a pair of fixed points. At room temperature, rubber stores enough kinetic energy so that each section of chain
oscillates chaotically, like the above piece of rope being shaken violently. The entropy model of rubber was developed in 1934 by
Werner Kuhn.
When rubber is stretched, the "loose pieces of rope" are taut and thus no longer able to oscillate. Their kinetic energy is given off as
excess heat. Therefore, the entropy decreases when going from the relaxed to the stretched state, and it increases during relaxation. This
change in entropy can also be explained by the fact that a tight section of chain can fold in fewer ways (W) than a loose section of chain,
at a given temperature (nb. entropy is defined as S=k*ln(W)). Relaxation of a stretched rubber band is thus driven by an increase in
entropy, and the force experienced is not electrostatic, rather it is a result of the thermal energy of the material being converted to kinetic
energy. Rubber relaxation is endothermic, and for this reason the force exerted by a stretched piece of rubber increases with temperature.
(Metals, for example, become softer as temperature increases). The material undergoes adiabatic cooling during contraction. This
property of rubber can easily be verified by holding a stretched rubber band to your lips and relaxing it. Stretching of a rubber band is in
some ways equivalent to the compression of an ideal gas, and relaxation is equivalent to its expansion. Note that a compressed gas
also exhibits "elastic" properties, for instance inside an inflated car tire. The fact that stretching is equivalent to compression may seem
somewhat counterintuitive, but it makes sense if rubber is viewed as a one-dimensional gas . Stretching reduces the "space" available to
each section of chain.
Vulcaniz ation of rubber creates more disulfide bonds between chains, so it shortens each free section of chain. The result is that the
chains tighten more quickly for a given length of strain, thereby increasing the elastic force constant and making rubber harder and less
extensible.
When cooled below the glass transition temperature, the quasi- fluid chain segments "freez e" into fixed geometries and the rubber
abruptly loses its elastic properties, although the process is reversible. This is a property it shares with most elastomers. At very low
temperatures, rubber is rather brittle; it will break into shards when struck or stretched. This critical temperature is the reason winter tires
use a softer version of rubber than normal tires. The failing rubber o- ring seals that contributed to the cause of the Challenger disaster
were thought to have cooled below their critical temperature; the disaster happened on an unusually cold day.

Current sources                                                                                                                               [edit]

Close to 21 million tons of rubber were produced in 2005, of which approximately 42% was natural. Since the bulk of the rubber produced
is of the synthetic variety, which is derived from petroleum, the price of natural rubber is determined, to a large extent, by the prevailing
global price of crude oil.[3][4] Today, Asia is the main source of natural rubber, accounting for about 94% of output in 2005. The three
largest producing countries, Thailand, Indonesia (2.4m tons) [5] and Malaysia, together account for around 72% of all natural rubber
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production. Natural rubber is not cultivated widely in its native continent of South America due to the existence of South American leaf
blight, and other natural predators of the rubber tree.

Cultivation                                                                                                                                    [edit]

                                               Rubber latex is extracted from rubber trees. The economic life period of rubber trees in
                                               plantations is around 32 years – up to 7 years of immature phase and about 25 years of
                                               productive phase.
                                               The soil requirement of the plant is generally well- drained weathered soil consisting of laterite,
                                               lateritic types, sedimentary types, nonlateritic red or alluvial soils.
                                               The climatic conditions for optimum growth of rubber trees consist of:
                                               Rainfall of around 250 cm evenly distributed without any marked dry season and with at least
                                               100 rainy days per year.

 Rubber is generally cultivated in
                                               Temperature range of about 20°C to 34°C with a monthly mean of 25°C to 28°C.
 large plantations. See the coconut shell      High atmospheric humidity of around 80%.
 used in collecting latex, in plantations in   Bright sunshine amounting to about 2000 hours per year at the rate of 6 hours per day
 Kerala, India
                                               throughout the year.
                                               Absence of strong winds.
Many high- yielding clones have been developed for commercial planting. These clones yield more than 2,000 kilograms of dry rubber
per hectare per year, when grown under ideal conditions and ideal field.

Collection                                                                                                                                     [edit]

In places like Kerala, where coconuts are in abundance, the half shell of coconut is used as the
collection container for the latex but glaz ed pottery or aluminium or plastic cups are more
common elsewhere. The cups are supported by a wire that encircles the tree. This wire
incorporates a spring so it can stretch as the tree grows. The latex is led into the cup by a
galvanised "spout" knocked into the bark. Tapping normally takes place early in the morning,
when the internal pressure of the tree is highest. A good tapper can tap a tree every 20 seconds
on a standard half- spiral system, and a common daily "task" siz e is between 450 and 650 trees.
Trees are usually tapped alternate or third daily, although there are many variations in timing,
length and number of cuts. The latex, which contains 25–40% dry rubber, is in the bark, so the
tapper must avoid cutting right through to the wood or the growing cambial layer will be
damaged and the renewing bark will be badly deformed, making later tapping difficult. It is usual
to tap a pannel at least twice, sometimes three times, during the trees' life. The economic life of
the tree depends on how well the tapping is carried out, as the critical factor is bark consumption.
A standard in Malaysia for alternate daily tapping is 25 cm (vertical) bark consumption per year.

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The latex tubes in the bark ascend in a spiral to the right. For this reason, tapping cuts usually
ascend to the left to cut more tubes.
The trees will drip latex for about four hours, stopping as latex coagulates naturally on the
tapping cut, thus blocking the latex tubes in the bark. Tappers usually rest and have a meal after
finishing their tapping work, then start collecting the latex at about midday. Some trees will
continue to drip after the collection and this leads to a small amount of cup lump which is              A woman in Sri Lanka in the process
                                                                                                         of harvesting rubber
collected at the next tapping. The latex that coagulates on the cut is also collected as tree lace.
Tree lace and cup lump together account for 10–20% of the dry rubber produced.
The latex will coagulate in cup if kept for long. The latex has to be collected before coagulation. The collected latex is transferred in to
coagulation tanks for the preparation of dry rubber or transferred into air- tight containers with sieving for ammoniation. Ammoniation is
necessary to preserve the latex in colloidal state for long.
Latex is generally processed into either latex concentrate for manufacture of dipped goods or it can be coagulated under controlled,
clean conditions using formic acid. The coagulated latex can then be processed into the higher grade technically specified block rubbers
such as SVR 3L or SVR CV or used to produce Ribbed Smoke Sheet grades.
Naturally coagulated rubber (cup lump) is used in the manufacture of TSR10 and TSR20 grade rubbers. The processing of the rubber for
these grades is basically a siz e reduction and cleaning process to remove contamination and prepare the material for the final stage of
drying.[6]
The dried material is then baled and palletiz ed for storage and shipment in various methods of transportation.

Transportation                                                                                                                             [edit]

Natural rubber latex is shipped from factories in South- West Asia, South America and North Africa to destinations around the world. As cost
of natural rubber has risen significantly, the shipping methods which offer the lowest cost per unit (kg, tonne or pound) are preferred.
Depending on the destination, warehouse availability, transportation conditions, some methods are more suitable to certain buyers than
others. In international trade, latex rubber is mostly shipped in 20 foot ocean containers. Inside the ocean container, various types of
smaller containers are used by factories to store latex rubber.[7]

Steel drums                                                                                                                                [edit]

205 kilogram or 55 gallon steel drums are the traditional method of packaging of natural latex. The drum is typically made of steel with a
ribbed outer to improve rigidity and durability. A 20 foot container can store 80 of such 55 gallon drums for a net weight of 16.40 metric
ton (16,400 kilogram or 36,080 "wet" pound) of latex. The use of drums allows bulk transportation to save cost yet permits flexibility in
retail distribution. A broker can sell in small quantity such as 1 or 2 drums.

ISO tanks                                                                                                                                  [edit]

These tanks are in fact the ocean container itself. They all have standard siz e of 20 foot x 8 foot x 8’6 foot. Their capacity is between
17,500 to 25,000 liters depending on the cylinder siz e and shape. These ISO tanks can also be used for transportation of liquid
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chemicals and food stuffs. This is the costliest shipping method, but also provides most convenient handling in some countries. Usually
the buyer has to buy the entire tank to enjoy the benefit of bulk saving.

Flexitank or Flexibag inside 20 f oot container                                                                                       [edit]

Flexitanks offer a much cheaper method of shipping than ISO tank, and they are widely used nowadays. The flexitank itself is a big PE
bag with a valve to for loading and later, unloading of the liquid content. The PE bag is placed inside a 20 foot container with proper
reinforcement near the container doors. The latex is then pumped into the PE bag, which is "blown up" as the amount of liquid increases.
Maximum of 21 tons of liquid latex can be stored inside a flexitank as this is a limit weight allowable on public streets and highways in
many countries. The container doors are closed, sealed, and are ready for load onto sailing ship. At destination, the rubber latex is
pumped out. The flexitank is discarded after use.

                           This article needs addit ional cit at ions f or verif icat ion. Please help improve this article by
                           adding citations to reliable sources. Unsourced material may be challenged and removed. (May
                           2012)


Other methods                                                                                                                         [edit]

Totes made of PE or corrugated paper of different siz es are sometimes used to transport latex rubber. Their footprints (bases) are often
similar to the siz e of a standard pallet (40 in x 48 in). However, these totes are less common as the other methods make the majority of
shipment volume in international trades.

Uses                                                                                                                                  [edit]

                                         The use of rubber is widespread, ranging from household to industrial products, entering the
                                         production stream at the intermediate stage or as final products. Tires and tubes are the largest
                                         consumers of rubber. The remaining 44% are taken up by the general rubber goods (GRG)
                                         sector, which includes all products except tires and tubes.

                                         Prehistoric uses                                                                             [edit]

                                         The first use of rubber was by the Olmecs, who centuries later passed on the knowledge of
                                         natural latex from the Hevea tree in 1600 BC to the ancient Mayans. They boiled the harvested
                                         latex to make a ball for a Mesoamerican ballgame.[8]

                                         Manufacturing                                                                                [edit]

                                         Other significant uses of rubber are door and window profiles, hoses, belts, matting, flooring and
                                         dampeners (antivibration mounts) for the automotive industry. Gloves (medical, household and
                                         industrial) and toy balloons are also large consumers of rubber, although the type of rubber
                                         used is that of the concentrated latex. Significant tonnage of rubber is used as adhesives in

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                                           many manufacturing industries and products, although the two most noticeable are the paper and
 Compression molded (cured) rubber         the carpet industries. Rubber is also commonly used to make rubber bands and pencil erasers.
 boots before the flashes are removed
                                           Many aircraft tires and inner tubes are still made of natural rubber due to the high cost of
                                           certification for aircraft use of synthetic replacements.

Textile applications                                                                                                                       [edit]

Additionally, rubber produced as a fiber sometimes called elastic, has significant value for use in the textile industry because of its
excellent elongation and recovery properties. For these purposes, manufactured rubber fiber is made as either an extruded round fiber
or rectangular fibers that are cut into strips from extruded film. Because of its low dye acceptance, feel and appearance, the rubber fiber
is either covered by yarn of another fiber or directly woven with other yarns into the fabric. In the early 1900s, for example, rubber yarns
were used in foundation garments. While rubber is still used in textile manufacturing, its low tenacity limits its use in lightweight garments
because latex lacks resistance to oxidiz ing agents and is damaged by aging, sunlight, oil, and perspiration. Seeking a way to address
these shortcomings, the textile industry has turned to Neoprene (polymer form of Chloroprene), a type of synthetic rubber as well as
another more commonly used elastomer fiber, spandex (also known as elastane), because of their superiority to rubber in both strength
and durability.

Vulcanization                                                                                                                              [edit]

   Main article: Vulcanization
Natural rubber is often vulcaniz ed, a process by which the rubber is heated and sulfur, peroxide or bisphenol are added to improve
resistance and elasticity, and to prevent it from perishing. The development of vulcaniz ation is most closely associated with Charles
Goodyear in 1839.[9] Carbon black is often used as an additive to rubber to improve its strength, especially in vehicle tires.

Allergic reactions                                                                                                                         [edit]

   Main article: Latex allergy
Some people have a serious latex allergy, and exposure to certain natural rubber latex products such as latex gloves can cause
anaphylactic shock. Guayule latex is hypoallergenic and is being researched as a substitute to the allergy- inducing Hevea latexes. Unlike
the sappable Hevea tree, these relatively small shrubs must be harvested whole and latex extracted from each cell. Chemical processes
may also be employed to reduce the amount of antigenic protein in Hevea latex, resulting in alternative Hevea- based materials such
Vytex Natural Rubber Latex that, while not completely hypoallergenic, do provide lessened exposure to latex allergens.
Some allergic reactions are not from the latex but from residues of other ingredients used to process the latex into clothing, gloves, foam,
etc. These allergies are usually referred to as multiple chemical sensitivity (MCS).

See also                                                                                                                                   [edit]

   Akron, Ohio, center of the rubber industry in the USA
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  Condoms, also called "rubbers"
  Emulsion dispersion
  Fordlândia, failed attempt to establish a rubber plantation in Braz il
  Reinforced rubber
  Resilin, a rubber substitute
  Rubber seed oil
  Rubber technology
  Stevenson Plan, historical British plan to stabiliz e rubber prices
  Charles Greville Williams, researched natural rubber being a polymer of the monomer isoprene

References                                                                                                                                         [edit]


Notes                                                                                                                                              [edit]
  1. ^ Burns, Bill. "The Gutta Percha Co mpany"       . History of the Atlantic Cable & Undersea Communications . Retrieved 20 0 9 -0 2-14.
         ab
  2. ^        Untitled Do cument
  3. ^ Overview o f the Causes o f Natural Rubber Price Vo latility
  4. ^ Sho rt run and lo ng run effects o f the wo rld crude o il prices o n the Malaysian natural rubber and palm o il expo rt prices
  5. ^ blo o mberg.co m
  6 . ^ Technical Grades and Basis fo r Grading by ASTM D2227           - Basic Rubber Testing
  7. ^ Transpo rtatio n o f Natural Rubber    - Industry So urce
  8 . ^ The Mayan-Olmec Co nnectio n
  9 . ^ Slack, Charles. "No ble Obsessio n: Charles Go o dyear, Tho mas Hanco ck, and the Race to Unlo ck the Greatest Industrial Secret o f the
      Nineteenth Century". Hyperio n 20 0 2. [ISBN 9 78 0 78 6 8 6 78 9 9 ]

Sources                                                                                                                                            [edit]

  Rubbery Materials and their Compounds by J.A Brydson
  Rubber Technology by Maurice Morton
  Hobhouse, Henry (2003, 2005). Seeds of Wealth: Five Plants That Made Men Rich . Shoemaker & Hoard. pp. 125–185. ISBN 1- 59376-
  089- 2.

Additional resources                                                                                                                               [edit]

  Database for natural rubber, by National Laboratories of Medicine

Bibliography                                                                                                                                       [edit]

  Ascherson, Neal: The King Incorporated , Allen & Unwin, 1963. ISBN 1- 86207- 290- 6 (1999 Granta edition).
  Hochschild, Adam: King Leopold’s Ghost: A Story of Greed, Terror, and Heroism in Colonial Africa , Mariner Books , 1998. ISBN 0- 330-

                                                                                                                                              PDFmyURL.com
    49233- 0.
    Petringa, Maria: Brazza, A Life for Africa . Bloomington, IN: AuthorHouse, 2006. ISBN 978- 1- 4259- 1198- 0

External links                                                                                                                                          [edit]

Hist ory
                                                                                                                            Look up natural rubber in
    History of the International Rubber Industry from 1870–1930 (Economic History Association)                              Wiktionary, the free dictionary.
    A Brief History of Rubber
    Rubber timeline                                                                                                       Wikimedia Commons has media
    Historical Rubber Prices                                                                                              related to: Rubber

Associat ions
    International Rubber Research and Development Board (IRRDB)
    Association of Natural Rubber Producing Countries (ANRPC)
    International Rubber Study Group (IRSG)
    Associação Paulista de Produtores e Beneficiadores de Borracha (APABOR), Braz il                   (Portuguese)
    Malaysian Rubber Board (LGM)
    Rubber Board Of India
    Thailand Rubber Association (TRA)
    Rubber Research Institute of Sri Lanka
Ot her
    Rubber- Chemical Compatibility Guide
    Basic Rubber Testing
    Fertiliz er–free rubber tree planting, - BioRubber

 Categories: Natural materials       Organic polymers       Terpenes and terpenoids        Rubber     Elastomers     Adhesives      Nonwoven fabrics



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