Key Materials: Historical Development and Modern Uses

Concept of Material

Materials refer to all raw substances used in the production of useful objects for people. The manipulation of these raw materials produces objects that improve living standards.

Material Classification by Source

• Natural: Animal, vegetable, and mineral.
• Artificial.

Brief History of Material Use

Stone Age

• Paleolithic (2.5 million – 10,000 years ago): Stone, bones, horn, leather.
• Neolithic: Ceramics (clay heated over 450°C), bitumen, collagen glue.

Metal Age

• 4000 BC (Mesopotamia): Copper, gold, silver.
• 3000 BC – Bronze Age: An alloy of copper and tin; harder and with a lower melting point than copper. Used for weapons production.
• 1000 – 1500 BC: Iron, glass, and then timber.
• 20th Century: Concrete (cement + water + gravel).

Evolution of New Material Use

It wasn't until almost the Industrial Revolution that new materials were truly discovered and began to appear. Innovations in science and technology during the Industrial Revolution led to the discovery and manufacturing of new materials.

Polymers

Polymers are materials composed of large molecules, which, in turn, are formed by the union of many smaller molecules called monomers.

Polymer Types

• Natural: Polymers found in nature.
• Transformation: Chemical modification of natural polymers (e.g., vulcanized rubber, celluloid).
• Synthetic: Derived from raw materials that are not initially polymers.

Examples of Polymers

• Rubber (natural)
• Vulcanized rubber (transformation)
• Plastics (refer to pages 208-211)
• Bakelite
• Starch (natural)
• Cellulose (natural)
• DNA (natural)
• Proteins (natural)

Rubber

Rubber is a natural polymer composed of many units of a hydrocarbon chain, with Isoprene (C₅H₈) as its monomer. It is found as a white emulsion (latex) in the sap of various plants but can also be produced synthetically.

• The main commercial source of latex is the Euphorbiaceae family.
• Other latex-producing plants include Ficus and the common dandelion.

Uses of Rubber

Rubber is widely used in manufacturing due to its excellent properties of elasticity and resistance against acids and alkaline substances. It is water-repellent and insulates against temperature and electricity. Common uses include:

• Tires and wheels
• Components for military airplanes
• Seals and insulation in skyscrapers
• Components in solar panels
• Waterproof articles
• Insulation for buildings