What is rubber?

2nd March 2020

What is rubber?

			Rubber is a tough, elastic substance consisting of elastomers (elastic polymers). Until the 20th century, rubber was always produced naturally, using latex found in the bark of various tropical trees and shrubs. However, nowadays, synthetic rubber is more common.

			Although Native Americans had been aware of the useful properties of natural rubber for centuries, it was first brought to Europe in the early 1700s. Today, natural rubber is mostly produced in Thailand, Indonesia and Malaysia. The latex used to make the rubber is drawn from trees through tapping, which involves a diagonal incision being made in their trunks to allow the sap to escape.

			In order to meet a growing demand which occurred as a result of the invention of the motor car, synthetic rubber was first manufactured at the beginning of the 20th century. Synthetic rubber is produced from crude oil. Around two thirds of new rubber produced is man-made and there are around twenty different types.

			A brief history
			Long before South America was discovered by Western explorers, South American Indians had been moulding items such as shoes and balls out of the dried latex produced by the rubber tree.

			In 1735, rubber samples were brought to Europe for the first time. Joseph Priestley recognised that the material could be used to rub out pencil marks from paper; it is for this reason that rubber got its name.

			In the early 1800s, Thomas Hancock, an inventor, learnt how to cut, roll and press rubber on an industrial scale. He also invented a masticator, a machine that enabled the further use of pieces of scrap rubber, bonding them to create a coherent mass that could be used again in manufacture.

			However, in its natural state, rubber still had a fundamental flaw; in extreme conditions, the material can change drastically. In hot temperatures, it is very soft and in the cold, it becomes hard and brittle. In order to tackle this problem, in 1839, Charles Goodyear developed the process of vulcanisation.

			Vulcanisation Both natural and synthetic rubber can be made tougher by vulcanisation, a curing process where the material is heated with sulphur. Vulcanisation was initially seen as a way of stabilising rubber and making it unsusceptible to extreme heat and cold. However, it also increases the material’s resistance to abrasion and makes it last longer.


			After the introduction of vulcanisation, as a result of its improved properties, the number of applications rubber could be used for grew significantly. Most importantly, because rubber could be made tougher than ever before, it could now be used to make tyres for bicycles, and later cars and aeroplanes. This development signalled the dawn of the modern rubber industry.

			As rubber emerged as an important industrial material, demand grew and South American countries including Brazil could no longer be the primary suppliers of rubber. In 1876, seeds were smuggled from Brazil to England and were planted in Kew Gardens. The seedlings were then shipped to Sri Lanka and Singapore, resulting in the establishment of the Asian rubber industry.

			Properties

ADVANTAGES

DISADVANTAGES

Waterproof
Resilient and tough
Resistant to heat build-up
High deformability – able to stretch and return to its original shape
An insulator of heat and electricity

Rubber that has not been properly vulcanised can deteriorate if it is exposed to sunlight for long periods


			Uses
			As a result of its toughness, flexibility and waterproof properties, rubber is widely used in the construction, medical and automobile sectors.

			Tool handles The handles of a variety of different tools are covered with a rubber grip because of the material’s excellent insulation of heat. Rubber handles on tools such as hammers, screwdrivers and pliers improve the comfort of the user and make the tools easier to grip.

			Vehicle tyres The most significant use of rubber is in tyres for cars, motorbikes and aircraft. This is a result of the material’s high resistance to wear and tear, in addition to its extreme gripping power which provides the tyres with traction.

			Hoses Because rubber is both waterproof and impermeable to gases, it is often used to make hosepipes and gas hoses.

			Mallets In roofing, rubber mallets are used to work sheet metal as they are hard enough to shape the material but won’t leave unsightly marks or dents.

			Gaskets Gaskets are sometimes made out of rubber as a result of its toughness and ability to deform. These properties enable rubber gaskets to withstand a great deal of pressure and to fit into the space between two mating surfaces.

			Waterproof clothing and footwear Rubber is also used to make the soles of shoes, including footwear for tradespeople. Shoes with rubber soles provide the user with excellent grip and wear-resistance so are likely to last a long time. Rubberised fabric is used to make waterproof clothing, usually jackets.