Everyone must have come across rubber products. There are many rubber products which we come across in our daily life. For example rubber gloves, rubber band, footwear, etc. We all have seen that rubber items have the ability to recover their shapes after being stretched or distorted and hence rubber is referred to as elastomers. It is an elastic substance which can be obtained both by naturally (natural rubber) or they can also be synthesized chemically in laboratories (synthetic rubber-like butyl rubber, neoprene, etc.)
Types of rubber
There are two types of rubber — Natural Rubber and Synthetic Rubber.
These are the elastomers which are obtained naturally. It is made up of solids particles suspended in milky white liquid, called latex that drips from the bark of tropical and subtropical trees. This latex rubber is mainly found in the 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 odor 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 shapes to rubber using rollers and 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 – Even after performing all these steps rubber is not much stronger and harder to be used in various 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 373 k to 415 k. This process is known as vulcanization. Sulphur acts as a cross-linking agent and after vulcanization, rubber gets cross-linked and becomes hard.
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 unsaturated monomer.
Preparation of synthetic rubbers:
- Neoprene (Polychloroprene): – It is a polymer of chloroprene, which 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.
This is just the brief layout of preparation of rubber products. To know more about the Natural Rubber products and how it is made. Kindly visit byju.com.