Natural Rubber and Synthetic Rubber

What are Rubber products?

There are many rubber products which we come across in our daily life. Some common rubber-based objects that we encounter in our day-to-day lives include rubber gloves, rubber bands, and rubber footwear. Rubber items have the ability to recover their shapes after being stretched or distorted, which is the reason why rubber can be classified as an elastomer. Rubber is an elastic substance which can be obtained both naturally (natural rubber) or artificially (they can also be synthesized chemically in laboratories; synthetic rubber-like butyl rubber, neoprene, etc.)

Table of Contents

Types of rubber

There are two primary types of rubber, namely natural rubber and synthetic rubber.

Natural rubber

These are the elastomers which are obtained naturally. Natural rubber is made up of solid particles suspended in a milky white liquid (called latex) that drips from the bark of certain tropical and subtropical trees. This latex rubber is mainly found in countries like Brazil, India, Indonesia, Malaysia, and Sri Lanka. It is made by the polymerization of isoprene (2 methyl-1, 3-butadiene) which has a chemical formula (C5H8) n and it is known as cis- 1, 4- polyisoprene. In simple words, we can say that they are made by loosely joining the monomers of isoprene (C5H8) in the form of a long tangled chain.

Preparation of Natural Rubber:

• Rubber tapping – The milky white liquid latex is collected from the rubber trees in a cup by making a slight V-cut on the tree bark. The collected latex is washed, filtered and reacted with acids to congeal the rubber particles.

 

• Mastication – The rubber obtained from the tapping process is still not ready to be used. When it is cold it is very brittle in nature and when warmed up it becomes very gluey. To remove the brittle nature and strong odour of the rubber, it is allowed to pass through the rollers and is pressed to make it softer and flexible to work. This process is repeated based on the properties that are required for the rubber. In this process, extra chemical ingredients are also added to enhance the properties of rubber.

 

• Calendering is a process which is mainly performed to provide shape to the rubber using rollers (after proper mixing of the chemical ingredients).

 

• The final product obtained is then extruded to make hollow tubes by passing them through specially designed holes in an extrusion machine.

 

• Vulcanization – Performing all the steps listed above will not yield rubber that is strong or hard enough to be used in items like car tires and machinery. To enhance all these properties, sulphur is added to the rubber and it is heated at a temperature ranging from 373 K to 415 K. This process is known as vulcanization. The sulphur acts as a cross-linking agent and after vulcanization, rubber gets cross-linked and becomes hard.

                                                                              

 

 

Synthetic rubbers

Synthetic rubbers are produced from petroleum and natural gas. It is obtained by polymerization of 1, 3 – butadiene derivatives or by copolymerization of 1, 3 – butadiene along with an unsaturated monomer.

Preparation of synthetic rubbers:

Neoprene (Polychloroprene): –

The monomer of Neoprene is 2-chloro-1,3-butadiene, it is commonly known as chloroprene. Neoprene is a polymer of chloroprene, which is formed by joining together the monomers of chloroprene.Buna- N:-

It is a copolymer of 1, 3 – butadiene and acrylonitrile, it is formed in the presence of a peroxide catalyst.

Uses of Rubber

Rubber can be used for various rubber and across various platforms, a few of them are mentioned below;

• It is used for lining chutes, bins and industrial mixers. Because of its water-proof and resilient property, it can be made into a good insulator.
• In the clothing industry, it can be used as wetsuits and expandable clothes such as gym and cycling shorts etc.
• Rubbers are also used for flooring purposes it gives padding and prevents fatigue along with being waterproof and slip-resistant.
• In the automobile industry, its use can be witnessed in tires, padding in brakes, airbags, seats, roofs etc.

This article only provides a brief introduction to the preparation of rubber products. To know more about natural rubber products and how they are made, register with BYJU’S and download our app.

Frequently Asked Questions-FAQs

Q1

1. What is the difference between natural and synthetic rubber?

Natural rubber is polyisoprene in which monomer units are of isoprene i,e 2-methyl-1,3 butadiene. Natural rubber is obtained in the form of solid particles suspended in a milky white liquid (called latex) that drips from the bark of certain tropical and subtropical trees. Neoprene is a synthetic rubber. The monomer of Neoprene is 2-chloro-1,3-butadiene, it is commonly known as chloroprene.

Additional reading:
Why Can't Natural Rubber Be Used to Make Products?
The effect of all kinds of packing element sealing ring
What is the Carbon Steel Butt Welding Pipe Reducer?
What Does Silicone Rubber React With?
Natural and synthetic rubber

Q2

2. What is vulcanisation rubber with an example?

Vulcanization is a chemical process in which the natural rubber is heated with sulphur, accelerator and activator at 373-415 K. Vulcanised rubber is better than natural rubber in the sense that it is more elastic, has less Water absorbing tendency and is more resistant to oxidation and towards organic solvent.

Q3

3. What is natural rubber used for?

Natural rubber is made up of solid particles suspended in a milky white liquid (called latex) that drips from the bark of certain tropical and subtropical trees. It is used in medical devices, surgical gloves, aircraft and car tires, pacifiers, clothes, toys, etc.

Q4

4. What are the disadvantages of natural rubber?

The disadvantages of natural rubbers are quite less resistant to attack by organic acid. It has little durability. When stretched to a greater extent, it suffers permanent deformation.

Q5

5. What are synthetic rubber examples?

Synthetic rubbers are produced from petroleum and natural gas. It is obtained by polymerization of 1, 3 – butadiene derivatives or by copolymerization of 1, 3 – butadiene along with an unsaturated monomer.

"" Charles Goodyear, the original rubber fan

Getty Images

What makes rubber so elastic? Like plastic, rubber is a polymer, which is a chain of repeating units called monomers. In rubber, the monomer is a carbon compound called isoprene that has two carbon-carbon double bonds. The latex fluid that seeps from rubber trees has many isoprene molecules. As the latex dries, the isoprene molecules crowd together and one isoprene molecule attacks a carbon-carbon double bond of a neighboring molecule. One of the double bonds breaks, and the electrons rearrange to form a bond between the two isoprene molecules.

The process continues until you have a long strands of many isoprene molecules linked like a chain. These long strands are called polyisoprene polymer. Each polyisoprene molecule contains thousands of isoprene monomers. As the drying continues, the polyisoprene strands stick together by forming electrostatic bonds, much like the attraction between opposite poles of two bar magnets. The attraction between these strands holds the rubber fibers together and allows them to stretch and to recover.

Advertisement

However, temperature changes can affect the electrostatic interactions between the polyisoprene strands in latex rubber. Hot temperatures reduce the interactions and make the rubber more fluid (sticky). Colder temperatures increase the interactions and make the rubber more solid (hard, brittle).

In the early 1800s, several scientists and inventors set out to make rubber more durable. One famous inventor, Charles Goodyear, reasoned that you could reduce rubber's stickiness by mixing it with various dry powders. He experimented by combining talcum and other powders with rubber. In 1838, Goodyear met Nathaniel Hayward, who had made progress in treating rubber sheets with a solution of sulfur and turpentine and then drying them in the sun. Hayward's sun-dried rubber was harder and more durable, so he patented the process, which he called solarization.

Goodyear purchased the patent rights to solarization and began experimenting with sulfur compounds. By trial and error, the inventor mixed latex rubber with sulfur and lead oxide. Legend has it that some of the mixture fell onto a hot stove, and the resulting rubber was hard, flexible and durable. Goodyear's a­ccidental process eventually became known as vulcanization. He also found that changing the amount of sulfur changed the rubber's characteristics. The more sulfur used, the harder the rubber became. So what happens when rubber is vulcanized?

When polyisoprene strands are heated with sulfur and lead oxide, the sulfur atoms attack the double bonds in the polyisoprene strands and bind to the carbon atoms. Sulfur atoms also can form bonds among themselves (disulfide bonds) and cross-link adjacent polyisoprene strands to form a netlike structure in the rubber.

­Thi­s cross-linking strengthens the polyisoprene to make it harder, flexible and more durable. As Goodyear found, the more sulfur used, the more cross-links can form, and the harder the rubber gets. Goodyear's vulcanization process involved combining latex rubber, sulfur and lead oxide in high-pressure steam for up to 6 hours to achieve the best results.

Rubber Prince or Pauper?

Charles Goodyear was obsessed with rubber. He even experimented with it while he was confined to debtor's prison. After he invented vulcanization in 1839, he started making sheets of vulcanized rubber that could be used for clothing. Goodyear sent his products to Europe in hopes of enticing investors. English inventor and rubber pioneer Thomas Hancock was enticed. He figured out Goodyear's vulcanization process and hastily applied for an English patent before Goodyear. Ultimately, many other businesses infringed on Goodyear's patents, and he spent much of his fortune on litigation or on rubber experiments. He died impoverished in 1860. He'd probably be happy to know that the Goodyear Tire and Rubber Company was named in his honor.