Natural rubber

Rubber, also called India rubber, latex, or caoutchouc, is a special material that comes from trees. It is made from a substance called polymers of isoprene, mixed with a few other natural compounds. The main source of natural rubber today is the Pará rubber tree, also known as Hevea brasiliensis. People get the rubber by making small cuts in the tree’s bark and collecting the sticky, white liquid that comes out. This liquid is called latex.

After collecting the latex, manufacturers clean and prepare it so it can be used to make many everyday products. Natural rubber is very stretchy, bounces back well after being stretched, and does not let water through. These properties make it very useful. It is used in things like tires, rubber bands, and many other items we use every day.

By the late 1800s, people needed more rubber than could be gotten from trees alone. This led to the creation of synthetic rubber, which is made from chemicals instead of trees. Today, countries such as Thailand, Malaysia, Indonesia, and Cambodia are some of the biggest producers of natural rubber in the world.

Varieties

The main source of natural rubber comes from the Amazonian rubber tree Hevea brasiliensis. This tree was first found in Brazil but is now grown around the world. It is used because it grows well on farms and can make rubber for many years.

Another type of rubber used to come from vines in Africa, called Congo rubber.

Dandelions have a special juice called latex, like rubber trees. In the past, scientists tried to use dandelions to make rubber but had trouble. Now, they have found a way to grow a special dandelion that could be used for rubber.

Many other plants can make latex, but not all are easy to use for rubber. Some give other useful materials, like gutta-percha or chicle. Other plants studied for rubber include the rubber fig Ficus elastica, Panama rubber tree Castilla elastica, and guayule Parthenium argentatum. The term gum rubber is used for rubber from trees, different from man-made rubber.

History

See also: Rubber boom

People in Mesoamerica were the first to use rubber. They made balls for games from the sap of the Hevea tree. Later, the Maya and Aztec people also used rubber to make balls and to keep things waterproof.

In 1736, Charles Marie de La Condamine brought rubber to France and told scientists about it. In England, Joseph Priestley found that rubber could clean pencil marks, which is why it is called “rubber.” Over time, people learned how to use rubber to make many things, like waterproof fabrics and tires.

In the 1800s, most rubber came from South America. Later, seeds from these trees were sent to places like India and Malaysia, where people began growing them too.

Before World War II, rubber was used to make many everyday items, such as tires, gloves, balloons, rubber bands, and erasers. It was also used in making clothes and adhesives.

Plants like guayule and the Kazakh dandelion are now being studied as possible new sources of rubber.

Properties

Rubber has special qualities that make it useful. When you stretch rubber, it can return to its original shape. If rubber gets very cold, it can become stiff and less stretchy.

Sometimes, rubber can develop unpleasant smells during storage and processing. The rubber industry uses special cleaning systems to reduce these odors.

Chemical makeup

Rubber is made of a special kind of molecule called cis-1,4-polyisoprene. It is very heavy, with a weight between 100,000 and 1,000,000 daltons. Natural rubber also includes a few other materials like proteins, fatty acids, and salts. Polyisoprene can also be made in a laboratory, but this is called synthetic rubber, which is different from natural rubber.

In rubber plants, tiny particles form inside special cells. These particles are surrounded by a thin membrane that helps them grow. The main building block for rubber is a molecule called isopentenyl pyrophosphate. It connects to other molecules to form the rubber. The process starts with a special enzyme that helps create the first part of the rubber molecule.

Production

A lot of rubber is made around the world. Over half of it is natural rubber. Most of it comes from Asia, with Thailand, Indonesia, and Vietnam making the most.

Natural rubber comes from rubber trees. These trees live for about 32 years. It takes about 7 years for them to start making rubber. The trees need warm temperatures, lots of rain, and humid air to grow well.

Rubber is collected by making small cuts in the tree bark. The liquid rubber flows into cups. This is done early in the morning when the tree's pressure is highest. The rubber must be collected before it hardens. It is then processed to make many products.

Rubber shortage and global economics

There is growing concern about the future supply of rubber. This is because of several factors, such as plant disease, changes in climate, and the changing price of rubber. Many rubber producers are small family farms that sell to big companies. When the price of rubber changes a lot, it can affect decisions to keep rubber trees, especially if other crops like palm oil become more profitable.

During the COVID-19 pandemic in 2020 and 2021, there was a big increase in the need for rubber gloves. This caused rubber prices to jump. In addition to the pandemic, the supply of rubber was low because some farms had switched to growing other crops, and some areas faced natural disasters. As a result, prices went up, which affected the cost of many products that use rubber.

Uses

Rubber can be used in many ways. Before it is treated, it is used in tapes, adhesives, and special blankets and shoes. After it is treated, called vulcanized rubber, it has even more uses.

Rubber is great for things that need to last a long time without wearing down, like the parts of car tires that touch the road or the belts that move things in machines. It also works well for things that need to bend and stretch, like hoses and balloons. Because rubber does not let air or water through easily, it is used to make raincoats, diving gear, and tubes for chemicals. It can also keep electricity from flowing where it shouldn’t, so it is used to protect wires and make safe gloves and shoes.

Allergic reactions

Main article: Latex allergy

Some people can react badly when they touch things made from natural rubber, like gloves. This is because of proteins in the rubber. Special processing can lower these proteins a lot, but not all the way.

There are other kinds of rubber from plants that are not the main rubber tree. People who have trouble with the main kind can sometimes use these other rubbers safely. Sometimes, reactions happen because of chemicals used to make the rubber, not the rubber itself. This is a different kind of reaction from the one caused by the rubber proteins.

Microbial degradation

Natural rubber can break down when certain types of bacteria are around. Bacteria such as Streptomyces coelicolor, Pseudomonas citronellolis, and Nocardia can break down rubber that has been treated in a special way. But it is not a good idea to put rubber things into regular compost, because rubber does not break down easily in normal compost conditions.