Shopping on line can be easy, simple and save you lots of money. It can also take a lot of your time, frustrate you, and result in unwanted purchases. Now the same can be said for regular high street shopping, but with the vast opportunity presented by the Internet it will pay you to spend a few minutes reading this and understanding how to better optimize your Rubber shopping experience:
1. Compare - without doubt the biggest advantage that the Rubber offers shoppers today is the ability to compare thousands of Rubber at a time. This is a great thing, but not necessarily all the time! Too much can be daunting at times so take advantage of the great comparison sites and where possible let them do the hard work for you.
2. Research - if it has been said it will be on the internet. Ignorance is no longer a justifiable reason for buying the wrong thing. Take the time to research in detail everything that you could possible want to know about
3. Testimonials - don't know anybody that has bought a Rubber? Wrong! If the Rubber is good the internet will let you know. Use the Internet as a friend and get testimonials before you buy.
4. Questions - Got a question about Rubber then search the Forums, FAQ's, Blogs etc. Don't be afraid to ask .....
5. Reputation - Never heard of the company selling Rubber? Don't worry, no reason why you should know every company in the world, but you know someone that does! Use the internet to find out what people are saying about Rubber and build up a picture of their reputation for sales, returns, customer service, delivery etc.
6. Returns - still worried that even after all of the above your Rubber wont be what you want? Check out the returns policy. There is so much competition now that someone, somewhere is bound to offer the terms that you are comfortable with.
7. Feedback - happy with your Rubber then let people know, after all you are depending on others people input in your buying decision, so why not give a little back.
8. Security - check for the yellow padlock on the Rubber site before you buy, and the s after http:/ /i.e. https:// = a secure site
9. Contact - got a question about Rubber, or want to leave a comment then check out the sites contact page. Reputable companies have them and respond.
10. Payment - ready to pay for your Rubber, then use your credit card or PayPal! Be aware of companies that don't accept them, there may be genuine reasons but given the huge amount of choice you have when buying online there is no reason at all not to buy via credit card or PayPal.
rubber treeNatural rubber is an elastic
hydrocarbon polymer that naturally occurs as a milky colloidal suspension, or
latex (rubber), in the sap of some plants. It can also be synthesized. The entropy model of rubber was developed in 1934 by Werner Kuhn.
Explanation
The major commercial source of natural rubber latex is the Para rubber tree,
Hevea brasiliensis (Euphorbiaceae). This is largely because it responds to wounding by producing more latex.
Henry Wickham gathered thousands of seeds from Brazil in 1876 and they were germinated in Kew Gardens, England. The seedlings were sent to
Colombo,
Indonesia, Singapore and
British Malaya. Malaya was later to become the biggest producer of rubber.
Liberia and Nigeria are examples of African rubber-producing countries.
Other plants containing latex include
figs (
Ficus elastica),
euphorbias, and the common dandelion. Although these have not been major sources of rubber, Germany attempted to use such sources during World War II when it was cut off from rubber supplies. These attempts were later supplanted by the development of
synthetic rubber.
Synthetic rubbers are made by the polymerization of a single monomer or a mixture of monomers to produce
polymers. These form part of a broad range of products extensively studied by polymer science and
rubber technology. Examples are SBR, or styrene-butadiene rubber, BR or butadiene rubber CR or chloroprene rubber and EPDM (ethylene-propylene-diene rubber)
Collection
in the process of harvesting rubber.In places like
Kerala, where coconuts are in abundance, the shell of half a coconut is used as the collection container for the latex. The shells are attached to the tree via a short sharp stick and the latex drips down into it overnight. This usually produces latex up to a level of half to three quarters of the shell. The latex from multiple trees is then poured into flat pans, and this is mixed with
formic acid, which serves as a coagulant resulting in rubber crump. After a few hours, the very wet sheets of rubber are wrung out by putting them through a press before they are sent onto factories where
vulcanization and further processing is done to it.
Chemical makeup
Aside from a few natural product impurities, natural rubber is essentially a
polymer of
isoprene units, a
hydrocarbon diene monomer. Synthetic rubber can be made as a polymer of isoprene or various other monomers. Rubber is believed to have been named by
Joseph Priestley, who discovered in 1770 that dried latex rubbed out pencil marks. The material properties of natural rubber make it an elastomer and a thermoplastic. However it should be noted that as the rubber is vulcanized it will turn into a thermoset. Most rubber in everyday use is vulcanized to a point where it shares properties of both i.e. if it is heated and cooled it is degraded but not destroyed.
History
In its native Central America and South America, rubber has been collected for a long time. The Mesoamerican civilizations used rubber mostly from
Castilla (plant). The Ancient Mesoamericans had a ball game using rubber balls (
see: Mesoamerican ballgame), and a few
Pre-Columbian rubber balls have been found (always in sites that were flooded under fresh water), the earliest dating to about 1600 BC. According to Bernal Díaz del Castillo, the Spain
Conquistadores were so astounded by the vigorous bouncing of the rubber balls of the Aztecs that they wondered if the balls were enchanted by evil spirits. The Maya civilization also made a type of temporary rubber shoe by dipping their feet into a latex mixture. Rubber was used in various other contexts, such as strips to hold stone and metal tools to wooden handles, and padding for the tool handles. While the ancient Mesoamericans did not have vulcanization, they developed organic methods of processing the rubber with similar results, mixing the raw latex with various saps and juices of other vines, particularly
Ipomoea alba, a species of
Morning glory.In
Brazil the natives understood the use of rubber to make water-resistant cloth. A story says that the first European to return to Portugal from Brazil with samples of such water-repellent rubberized cloth so shocked people that he was brought to court on the charge of witchcraft.
When samples of rubber first arrived in England, it was observed by
Joseph Priestley, in 1770, that a piece of the material was extremely good for rubbing out
pencil marks on paper, hence the name eraser.
The para rubber tree initially grew in South America, where it was the main source of what limited amount of latex rubber was consumed during much of the 19th century. About 100 years ago, the Congo Free State in Africa was a significant source of natural rubber latex, mostly gathered by forced labor. The Congo Free State was forged and ruled as a personal colony by the Belgian
King Leopold II. After repeated efforts (see
Henry Wickham) rubber was successfully cultivated in Southeast Asia, where it is now widely grown.
In
India commercial cultivation of natural rubber was introduced by the British Planters, although the experimental efforts to grow rubber on a commercial scale in India were initiated as early as 1873 at the Botanical Gardens,
Kolkata. The first commercial Hevea plantations in India were established at Thattekadu in Kerala in 1902.
The Rubber Board is a statutory body constituted by the Government of India, under the Rubber Act 1947, for the overall development of the rubber industry in the country.The head office of the rubber board is situated in Kottayam, Kerala, where the main production of natural rubber.
Properties
Rubber exhibits unique physical and chemical properties.
Rubber's stress-strain behavior exhibits the
Mullins effect, the
Payne effect and is often modeled as
Hyperelastic material.
Rubber
Strain crystallization.
Why does rubber have elasticity?
In most elastic materials, such as metals used in Coil spring, the elastic behavior is caused by
Chemical bond distortions. When force is applied, bond lengths deviate from the (minimum energy) equilibrium and strain energy is stored electrostatic potential. 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 thermal energy, as well as electrostatically.
In its relaxed state rubber consists of long, coiled-up polymer chains that are
Disulfide bond at a few points. Between a pair of links each monomer can rotate freely about its neighbour. This gives 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.
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. 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 in 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 counter-intuitive, but it makes sense if rubber is viewed as a
one-dimensional gas. Stretching reduces the "space" available to each section of chain.
Vulcanization of rubber creates more disulphide bonds between chains so it makes each free section of chain shorter. The result is that the chains tighten more quickly for a given length of
strain. This increases the elastic force constant and makes rubber harder and less extendable.
When cooled below the glass transition temperature, the quasi-fluid chain segments "freeze" into fixed geometries and the rubber abruptly loses its elastic properties, though the process is reversible. This is a property it shares with most elastomers. At very cold temperatures rubber is actually rather brittle; it will break into shards when struck or stretched. This critical temperature is the reason that 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 of rubber
Close to 21 million tons of rubber were produced in 2005 of which around 42% was natural. Today
Asia is the main source of natural rubber, accounting for around 94% of output in 2005. The three largest producing countries (Indonesia, Malaysia and Thailand) together account for around 72% of all natural rubber production.
Hypoallergenic rubber can be made from
Guayule.
Early experiments in the development of synthetic rubber led to the invention of
Silly Putty.
Natural rubber is often Vulcanization, a process by which the rubber is heated and sulfur, peroxide or bisphenol are added to improve resilience and elasticity, and to prevent it from
vulcanization#Reason for vulcanizing. Vulcanization greatly improved the durability and utility of rubber from the 1830s on. The successful development of vulcanization is most closely associated with
Charles Goodyear. Carbon black is often used as an additive to rubber to improve its strength, especially in vehicle tires.
Kottayam District of Kerala is the leader in rubber production among the states of
India. The rubber plant is not a native plant of India. Dutch colonialists who also cultivated rubber in their plantations in Indonesia introduced the rubber plant to Kerala, India, because of its similar tropical climate.
Uses
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, accounting for around 56% total consumption in 2005. The remaining 44% are taken up by the general rubber goods (GRG) sector, which includes all products except tires and tubes.
Other significant uses of rubber are door and window profiles, hoses, belts, and dampeners for the
automotive industry in what is known as the "under the bonnet" products. Gloves (medical, household and industrial) are also large consumers of rubber and toy balloons, although the type of rubber used is that of the concentrated latex. Significant tonnage of rubber is used as
adhesives in many manufacturing industries and products, although the two most noticeable are the paper and the carpet industry.
Additionally, rubber produced as a fiber 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, its hand 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 1900’s, 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 oxidizing agents and is damaged by aging, sunlight, oil, and perspiration. Seeking a way to address these shortcomings, the textile industry has turned to
Neoprene (chloroprene rubber), 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. Rubber is also commonly used to make rubber bands and balloons, although latex can be used as well.
See also
External links
- International Rubber Research & Development Board
- History of the International Rubber Industry from 1870-1930 from EH.NET
- Rubber Board Of India
- Rubber Division of ACS
- Rubber timeline
- Stop Firestone's Use of Child Labor in Rubber Production
rubber treeNatural rubber is an elastic
hydrocarbon polymer that naturally occurs as a milky colloidal suspension, or
latex (rubber), in the sap of some plants. It can also be synthesized. The
entropy model of rubber was developed in 1934 by
Werner Kuhn.
Explanation
The major commercial source of natural rubber latex is the Para rubber tree,
Hevea brasiliensis (
Euphorbiaceae). This is largely because it responds to wounding by producing more latex. Henry Wickham gathered thousands of seeds from Brazil in 1876 and they were germinated in Kew Gardens, England. The seedlings were sent to
Colombo,
Indonesia,
Singapore and British Malaya. Malaya was later to become the biggest producer of rubber. Liberia and Nigeria are examples of African rubber-producing countries.
Other plants containing latex include figs (
Ficus elastica),
euphorbias, and the common
dandelion. Although these have not been major sources of rubber, Germany attempted to use such sources during World War II when it was cut off from rubber supplies. These attempts were later supplanted by the development of
synthetic rubber.
Synthetic rubbers are made by the
polymerization of a single monomer or a mixture of monomers to produce polymers. These form part of a broad range of products extensively studied by polymer science and
rubber technology. Examples are SBR, or styrene-butadiene rubber, BR or butadiene rubber CR or chloroprene rubber and EPDM (ethylene-propylene-diene rubber)
Collection
in the process of harvesting rubber.In places like
Kerala, where coconuts are in abundance, the shell of half a coconut is used as the collection container for the latex. The shells are attached to the tree via a short sharp stick and the latex drips down into it overnight. This usually produces latex up to a level of half to three quarters of the shell. The latex from multiple trees is then poured into flat pans, and this is mixed with
formic acid, which serves as a coagulant resulting in rubber crump. After a few hours, the very wet sheets of rubber are wrung out by putting them through a press before they are sent onto factories where vulcanization and further processing is done to it.
Chemical makeup
Aside from a few natural product impurities, natural rubber is essentially a polymer of
isoprene units, a hydrocarbon
diene monomer. Synthetic rubber can be made as a polymer of isoprene or various other monomers. Rubber is believed to have been named by
Joseph Priestley, who discovered in 1770 that dried latex rubbed out pencil marks. The material properties of natural rubber make it an
elastomer and a
thermoplastic. However it should be noted that as the rubber is vulcanized it will turn into a thermoset. Most rubber in everyday use is vulcanized to a point where it shares properties of both i.e. if it is heated and cooled it is degraded but not destroyed.
History
In its native Central America and South America, rubber has been collected for a long time. The
Mesoamerican civilizations used rubber mostly from
Castilla (plant). The Ancient Mesoamericans had a ball game using rubber balls (
see: Mesoamerican ballgame), and a few
Pre-Columbian rubber balls have been found (always in sites that were flooded under fresh water), the earliest dating to about 1600 BC. According to
Bernal Díaz del Castillo, the
Spain Conquistadores were so astounded by the vigorous bouncing of the rubber balls of the Aztecs that they wondered if the balls were enchanted by evil spirits. The Maya civilization also made a type of temporary rubber shoe by dipping their feet into a latex mixture. Rubber was used in various other contexts, such as strips to hold stone and metal tools to wooden handles, and padding for the tool handles. While the ancient Mesoamericans did not have vulcanization, they developed organic methods of processing the rubber with similar results, mixing the raw latex with various saps and juices of other vines, particularly
Ipomoea alba, a species of
Morning glory.In Brazil the natives understood the use of rubber to make water-resistant cloth. A story says that the first European to return to Portugal from Brazil with samples of such water-repellent rubberized cloth so shocked people that he was brought to court on the charge of witchcraft.
When samples of rubber first arrived in England, it was observed by
Joseph Priestley, in 1770, that a piece of the material was extremely good for rubbing out
pencil marks on paper, hence the name
eraser.
The para rubber tree initially grew in
South America, where it was the main source of what limited amount of latex rubber was consumed during much of the 19th century. About 100 years ago, the
Congo Free State in Africa was a significant source of natural rubber latex, mostly gathered by forced labor. The Congo Free State was forged and ruled as a personal colony by the Belgian
King Leopold II. After repeated efforts (see
Henry Wickham) rubber was successfully cultivated in Southeast Asia, where it is now widely grown.
In India commercial cultivation of natural rubber was introduced by the British Planters, although the experimental efforts to grow rubber on a commercial scale in India were initiated as early as 1873 at the Botanical Gardens, Kolkata. The first commercial Hevea plantations in India were established at Thattekadu in Kerala in 1902.
The Rubber Board is a statutory body constituted by the Government of India, under the Rubber Act 1947, for the overall development of the rubber industry in the country.The head office of the rubber board is situated in Kottayam, Kerala, where the main production of natural rubber.
Properties
Rubber exhibits unique physical and chemical properties.
Rubber's stress-strain behavior exhibits the Mullins effect, the
Payne effect and is often modeled as Hyperelastic material.
Rubber
Strain crystallization.
Why does rubber have elasticity?
In most elastic materials, such as metals used in
Coil spring, the elastic behavior is caused by
Chemical bond distortions. When force is applied, bond lengths deviate from the (minimum energy) equilibrium and strain energy is stored electrostatic potential. 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 thermal energy, as well as electrostatically.
In its relaxed state rubber consists of long, coiled-up polymer chains that are Disulfide bond at a few points. Between a pair of links each monomer can rotate freely about its neighbour. This gives 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.
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. 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 in 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 counter-intuitive, but it makes sense if rubber is viewed as a
one-dimensional gas. Stretching reduces the "space" available to each section of chain.
Vulcanization of rubber creates more
disulphide bonds between chains so it makes each free section of chain shorter. The result is that the chains tighten more quickly for a given length of strain. This increases the elastic force constant and makes rubber harder and less extendable.
When cooled below the
glass transition temperature, the quasi-fluid chain segments "freeze" into fixed geometries and the rubber abruptly loses its elastic properties, though the process is reversible. This is a property it shares with most elastomers. At very cold temperatures rubber is actually rather brittle; it will break into shards when struck or stretched. This critical temperature is the reason that
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 of rubber
Close to 21 million tons of rubber were produced in 2005 of which around 42% was natural. Today Asia is the main source of natural rubber, accounting for around 94% of output in 2005. The three largest producing countries (Indonesia, Malaysia and Thailand) together account for around 72% of all natural rubber production.
Hypoallergenic rubber can be made from Guayule.
Early experiments in the development of synthetic rubber led to the invention of
Silly Putty.
Natural rubber is often Vulcanization, a process by which the rubber is heated and sulfur, peroxide or bisphenol are added to improve resilience and elasticity, and to prevent it from vulcanization#Reason for vulcanizing. Vulcanization greatly improved the durability and utility of rubber from the 1830s on. The successful development of vulcanization is most closely associated with Charles Goodyear.
Carbon black is often used as an additive to rubber to improve its strength, especially in vehicle tires.
Kottayam District of
Kerala is the leader in rubber production among the states of India. The rubber plant is not a native plant of India. Dutch colonialists who also cultivated rubber in their plantations in Indonesia introduced the rubber plant to Kerala, India, because of its similar tropical climate.
Uses
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, accounting for around 56% total consumption in 2005. The remaining 44% are taken up by the general rubber goods (GRG) sector, which includes all products except tires and tubes.
Other significant uses of rubber are door and window profiles, hoses, belts, and dampeners for the automotive industry in what is known as the "under the bonnet" products. Gloves (medical, household and industrial) are also large consumers of rubber and toy balloons, although the type of rubber used is that of the concentrated latex. Significant tonnage of rubber is used as
adhesives in many
manufacturing industries and products, although the two most noticeable are the paper and the carpet industry.
Additionally, rubber produced as a fiber 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, its hand 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 1900’s, 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 oxidizing agents and is damaged by aging, sunlight, oil, and perspiration. Seeking a way to address these shortcomings, the textile industry has turned to
Neoprene (chloroprene rubber), 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. Rubber is also commonly used to make
rubber bands and balloons, although latex can be used as well.
See also
External links
- International Rubber Research & Development Board
- History of the International Rubber Industry from 1870-1930 from EH.NET
- Rubber Board Of India
- Rubber Division of ACS
- Rubber timeline
- Stop Firestone's Use of Child Labor in Rubber Production
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