There are many different types of raw materials in rubber products , but they are divided into two categories:
Natural rubber (vegetable latex) and synthetic rubber (manufactured in a chemical factory or laboratory).
Commercially, the most important synthetic rubbers are styrene butadiene (SBR), polyacrylic and polyvinyl acetate (PVA);
Other types include polyvinyl chloride (PVC), polychloroprene (commonly known as neoprene), and various types of polyurethane.
Although natural rubber and synthetic rubber are similar in some ways, they are manufactured through completely different processes and are completely different chemically.
Natural rubber is made from a flowing milky white liquid called latex, which exudates when you cut into certain plants.
For example, common dandelions produce latex; if you break their stems, you can see latex dripping from them.
In theory, there is no reason why we ca n’t make rubber by planting dandelion. Although more than 200 plants in the world can be used to produce latex, more than 99% of the natural rubber in the world is made of a rubber tree called Hevea brasiliensis. Made of latex made from tree species.
The latex has about one-third of water and one-third of rubber particles, and this form is called a colloidal suspension. Natural rubber is a polymer of isoprene (also known as 2-methyl-1,3-butadiene) and has a chemical formula (C 5 H 8) n.
More simply, it is made up of thousands of basic C 5 H 8 units (isoprene monomers) loosely connected to form a long, tangled chain.
These molecular chains can be pulled apart quite easily, but if you release them, they will spring back directly-that's why rubber is elastic.
Synthetic rubber is made from petrochemicals in chemical plants.
The first and most famous: Neoprene (trade name of polychloroprene), which is made by the reaction of acetylene and hydrochloric acid.
Another synthetic rubber: emulsion styrene-butadiene rubber (E-SBR) is widely used in the manufacture of vehicle tires.
This article focuses on natural rubber.
The production of rubber articles from natural rubber requires several different steps.
1. First, latex must be collected from the rubber tree using a traditional process called rubber tapping.
This involves making a wide V-shaped incision in the bark of the tree. When the latex drips out, it is collected in a cup.
2. The latex from many trees is then filtered, washed and reacted with acid to coagulate (glue together) the rubber particles.
The rubber made in this way is pressed into thick sheets or flakes and then dried, ready for the next stage of production.
In addition, when it gets cold, it tends to get cold, stinky, sticky, and sticky.
Further processing is used to turn it into a more versatile material.
3. A kind of mechanical processing first called "chewing machine", using mechanical rollers and pressure to "chew" raw rubber, making it softer, easier to operate, and more sticky.
After the rubber is plasticized, additional chemicals are mixed to improve its performance (for example, to make it more resistant to abrasion).
4. Next, the rubber is flattened by a roller (called the process of calendering), or extruded through a specially shaped hole to form a hollow tube (a process called extrusion).
5. Finally, vulcanize the rubber (cooking): add sulfur and heat the rubber to about 140 ° C (280 ° F) in an autoclave (an industrial pressure cooker).
Hevea brasiliensis, as its name suggests, originally came from Brazil, and was introduced outside the Far East, such as Malaysia, Indonesia, Myanmar, Cambodia, China and Vietnam.
During World War II, when military demand was huge, the supply of natural rubber in these countries was cut off, which accelerated the development of synthetic rubber, especially in Germany and the United States.
Today, most natural rubber still comes from the Far East, and Russia and its former Soviet Union countries, France, Germany and the United States are the world's leading producers of synthetic rubber.
The world's largest single source of latex rubber is the Harbel Rubber Plantation near Monrovia, Liberia, which was established by the Firestone Tire Company in the 1920s and 1930s.
The physical and chemical properties of a material determine its use. Even if you don't know anything about the true use of rubber, you can make some correct guesses.
For example, everyone knows that rubber is strong, resilient, durable, and waterproof, so it is conceivable that it can be used in waterproof clothing.
There are many rubber products , but the most important use of rubber is for car tires; about half of the world's rubber ends up being wound on the wheels of cars, bicycles and trucks!
Because it is highly impermeable to gas, the tire can remain inflated for a long time.
Not only can rubber become soft, but it can also become hard. It is because of these qualities that the range of its use has been greatly increased.
Soft and flexible latex is used in a variety of everyday products, from erasers, balloons, protective gloves, adhesives to coatings.
Hard rubber can be used as a cushion for shock absorption and inflatable boats.
Because rubber is strong, flexible, and has poor thermal and electrical conductivity, it is also commonly used as a cable.
In addition, it has a wide range of applications: from artificial hearts to waterproof gaskets for washing machine doors, you will find a variety of applications for it!
Neoprene is more famous among various rubbers, but it has far more applications than most people know. Not only is it often used in medicine, but it is also widely used because of its flexibility and water resistance. Building materials such as roof and floor sealants.
Although the world has a huge demand for new rubber, we also produce a large amount of rubber waste, especially discarded automobile tires.
According to the Rubber Manufacturers Association, the United States produced nearly 270 million waste rubber automotive tires in 2011 alone, accounting for about a third of global tire usage.
Although some of them are used to make floors such as children's playgrounds, more than half of them are wasted (whether burned as fuel or buried in landfills).
The editor here reminds you that although rubber is good, pay attention to environmental protection ~
1492: Long before Columbus discovered the American continent, Indians living in Central and South America had learned how to use rubber latex to make waterproof clothes and shoes. They call it rubber tree "cahuchu" (crying wood), which is why French rubber is still called natural rubber today (pronounced "cow-chew").
1731: During the South American expedition, the French explorer Charles Marie de La Condamine sent rubber samples back to Europe, arousing strong scientific interest.
1770: The discoverer of oxygen, British scientist Joseph Priestley discovered that he could use a rubber sheet to erase the marks of a pencil on paper. In England, the eraser is still widely known today as "rubber."
1791: British Samuel Peal develops a method for making waterproof fabrics from rubber solutions.
1818: James Syme, a student of the Scottish Medical College, uses rubber-coated cloth to make raincoats.
1839: American inventor Charles Goodyear throws a piece of material (treated with sulfur) onto a hot furnace and accidentally discovers how to vulcanize rubber.
1876: British explorer Sir Henry Wickham smuggles thousands of seeds from the Brazilian rubber tree Hevea brasiliensis and returns to England.
The British planted seeds at Kew Gardens just outside London and exported them to various Asian countries, building giant plantations that now supply most of the world's rubber.
1877: American rubber manufacturer Chapman Mitchell develops the first process to recycle rubber.
1882: John Boyd Dunlop invents pneumatic (pneumatic) rubber tires. Since then, demand for rubber has increased dramatically.
1930: A team of DuPont American chemists led by Wallace Carothers develops a revolutionary synthetic rubber called polychloroprene and sells it in the form of neoprene. (Soon after, the same group developed a more revolutionary material: nylon)
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